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Kant, Immanuel

Kant, Immanuel

(b. Königsberg, Germany [now Kaliningrad, R.S.F.S.R.], 22 April 1724; d. Königsberg, 12 February 1804)

philosophy of science.

Kant was the fourth child of Johann Georg Cant and Anna Regina (Reuter) Cant. His paternal grandfather was an immigrant from Scotland, where the name Cant is still not uncommon in the northern parts. Immanuel changed the spelling to Kant in order that the name might conform more comfortably with the usual pratices of German pronunciation. His father was a saddle maker of modest means. His mother was much given to Pietism, a Protestant sect (not unlike the Quakers and early Methodists) which flourished in northern Germany at the time.

When Kant was ten, he entered the Collegium Fridericianum, intending to study theology. But he actually spent more time with classics, and he became quite adept in Latin. In 1740 he entered the University of Königsberg and studied mainly mathematics and physics with Martin Knutzen and Johann Teske. These years doubtless influenced him much in his interest in the philosophy of science. In 1746 Kant’s father died, and he was forced to interrupt his studies to help care for his brother and three sisters by being a private tutor in three different families successively for a period of some nine years. Finally, in 1755 he was able to resume his studies at the university and received his doctorate in philosophy in the autumn of that year. For the next fifteen years he earned a meager living as a Privatdozent lecturing on physics and nearly all aspects of philosophy. In 1770 he was given the chair of logic and metaphysics at the University of Königsberg, a position which he held until he retired in 1797.

Although Kant was brought up in Pietistic surroundings and in his youth even considered becoming a minister, in his maturity he became the one who, above all others, liberated philosophy and science from theology. His single-minded devotion to both philosophy and science also accounts largely for the fact that he never married. He was slightly built and gave the appearance of having a delicate constitution, but his careful attention to the laws of health and the regularity of his habits enabled him to live to be almost eighty.

Kant was very modest in his style of living. In 1783 he purchased a house in the center of town and quite regularly thereafter entertained friends at dinner. The number of his table companions was never large because his dinner service could accommodate but six persons. These companions were for the most part men of great culture and learning, and his dinners were widely known for the liveliness and diversity of the conversation.

The German writer Johann Gottfried von Herder said that Kant in his prime had the happy sprightliness of a boy and that he continued to have much of it even as an old man. He had a broad forehead, Herder continued, that was built for thinking and that was the seat of an imperturbable cheerfulness and joy. Speech rich in thought issued from his lips. He also possessed playfulness, wit, and humor. He enlivened his lectures and conversations by drawing on the history of men and peoples and on natural history, science, mathematics, and his own observations. He was indifferent to nothing that was worth knowing, concluded Herder.

Even though Kant is widely considered to be one of the two or three greatest philosophers that Western civilization has produced, he was also much interested in science and especially in the philosophy of science. He was not an experimental scientist and did not contribute to the body of scientific knowledge, but he was much concerned with the foundations of science and made significant contributions to that field. He has sometimes been accused (as by Erich Adickes in his Kant als Naturforscher) of being an armchair scientist. He might more accurately be called an armchair philosopher speculating on the fundamental bases of science. He was not interested in gleaning facts and data; rather, he speculated concerning the grand scheme in which the facts gleaned by others are arrayed.

The two main influences on Kant in his philosophical reflections on science were Leibniz and Newton. During his first period of study at the University of Königsberg, from 1740 to 1746, Knutzen taught that version of Leibniz’s metaphysics which the German philosopher Christian von Wolff had made popular. He also taught the mathematical physics which Newton had developed. He revealed to the young Kant the various oppositions, puzzles, and contradictions of these two great natural philosophers.

The nature of space and time was what interested the young Kant most in these disputes between Leibniz and Newton. He studied the famous exchange of letters between Leibniz and Samuel Clarke, a defender of Newton’s philosophy. Leibniz claimed that the universe is made up of an infinitude of monads, which are simple, immaterial (spiritual) substances. Every monad is endowed with some degree of consciousness. He conceived of space as a set of relations which the monads have to one another; it is the order of coexistent things. He thought of time as the relations of the successive states of consciousness of a single monad. Physical bodies, on this theory, are groups of monads. Mathematically considered, every monad is a dimensionless point. Length, breadth, and position can be represented as relations of monads. Space, then, is a continuous, three-dimensional system of mathematical points corresponding to the order of a plenum of distinct monads. Time has but one dimension; succession and coexistence are the only temporal relations, corresponding, as they do, to the order of perceptions in the consciousness of a monad. For Leibniz, then, space and time were relations among things (monades) which would have no existence whatever if there were no monads.

By contrast, Newton held that space and time are infinite and independent of the physical bodies that exist in space and time. For him space and time were things, and they would exist even if there were no bodies. He held that are absolute positions in space and time that are independent of the material entities occupying them and, furthermore, that empty space (void) and empty time are possible. Leibniz denied both tenets. Neither Leibniz nor Clarke was able fully to undermine the position of the other, and the result was an impasse.

In his early years Kant pondered the nature of space and time first from the point of view of Leibniz and then of Newton, but eventually he found both positions unsatisfactory. In his Thoughts on the True Estimation of Living Forces (1747) he took Leibniz’s view and tried to explain the nature of space by means of the forces of unextended substances (monades) that cause such substances to interact. He attempted to account for the threefold dimensionality of space by appealing to the laws that govern such interactions; but he was not very successful, as he himself admitted.

In his On the First Ground of the Distinction of Regions in Space (1768) Kant took Newton’s view that space is absolute and argued against Leibniz’s relational theory of space. He used the example of a pair of human hands. They are perfect counterparts of one another, yet they are incongruent (like left-and right-hand spirals). The two hands are identical as far as their spatial relations are concerned, but they are, nevertheless, spatially different. Therefore space is not just the relationship of the parts of the world to one another.

When Kant was inaugurated as professor of logic and metaphysics in 1770, he submitted a dissertation, in accordance with the custom of the time. It was entitled On the Form and Principles of the Sensible and Intelligible World. Here his views on space and time had developed to a point that was very close to the views enunciated in the Critique of Pure Reason (1781). Space and time are the schemata and conditions of all human knowledge based on sensible intuition. Our concepts of space and time are acquired from the action of the mind in coordinating its sensa according to unchanging laws. The sensa are produced in the mind by the presence of some physical object or objects. Space and time are now based epistemologically on the nature of the mind rather than ontologically on the nature of things, either as a relation among monads (Leibniz) or as a thing (Newton’s absolute space). Kant had turned from modes of being to ways of knowing. This new epistemological view of space and time provided him with a way of reconciling the opposed views of Leibiz and Newton. Space and time are indeed the relational orders of contemporaneous objects and successive states, inasmuch as space and time are the conditions of intuitive representations of objects, rather than being mere relations of independent substances (monads). Space and time are indeed absolute wholes in which physical objects are located, inasmuch as they are forms of sensible intuition lying ready in the mind, rather than being independently existing containers for physical objects.

Kant’s in the Critique differ from those of the Dissertation in that space and time are held in the former to be passive forms of intuition by means of which a manifold of sensa are presented to the understanding, which has the active function of synthesizing this manifold. Space is the form of all appearances of the external senses, just as time is the form of all appearances of the internal sense. As such, space and time are nothing but properties of the human mind. Everything in our knowledge that belongs to spatial intuition (extension), change according to which change of location is determined. The representations of the external senses are set in time, which contains nothing but relations of succession, coexistence, and duration.

Geometry is based on the pure intuition of space. To say that a straight line is the shortest distance between two points involves an appeal to spatial intuition. The concept of straight is merely qualitative. The concept of shortest is not already contained in the concept of straight but is an addition to straight through recourse to the pure intuition of space. Accordingly, the propositions of geometry are not analytic but a priori synthetic. So are the propositions of arithmetic. The concept of units in the pure intuition of time. Leibniz had claimed that the propositions of mathematics are analytic. For Kant even some of the propositions of mechanics cannot attain its concepts of motion without employing the representation of time.

As we have seen, Kant rejected Newton’s absolute space conceived as an independently existing whole containing all physical objects. In the Metaphysical Foundations of Natural Science (1786) he pointed out a meaning for “absolute space” which makes it a legitimate idea. At the beginning of “Phoronomy” in that treatise, he distinguishes relative space from absolute space. Relative (or material or empirical) space is the sum total of all objects of experience (bodies). Such space is movable because it is defined by material entities (bodies). If the motion of a movable space is to be perceived, that space must be contained in another, larger space in which it is to move. This larger space must be contained in another, still larger one, and so on to infinity. Absolute space is merely that largest space which includes all relative ones and in which the relative ones move. As such, absolute (empty) space cannot be perceived because it is not defined by material entities, as relative (empirical) spaces are, and so exists merely in idea, with no actual ontological status. Kant claimed that Newton mistakenly endowed such absolute space with ontological significance.

The terms “physical entities,” “material objects,” “bodies,” and similar ones have been used from time to time in the foregoing discussion without any exact definitions being given for them. They are all roughly analogous terms and involve what Kant usually calls “matter” or “body.” Toward the end of the “Dynamics” in the Metaphysical Foundations of Natural Science he does say that a body is matter between determinate boundaries and thus has definite shape. “Matter” is therefore a more general term than “body,” but he often uses the two interchangeably. What, indeed, is matter for Kant? In the development of his thought at the stage of the Dissertation, he distinguished a sensible world from an intelligible one. The former is the world which sense reveals, and the latter is what the intellect reveals. He called the former world phenomenal and the latter noumenal. The former is the world of things as they appear, while the latter consists in things as they are. Sensibility with its two pure forms, space and time, provides the foundation for the validity of physics and geometry; however, the scope of the application of these two sciences is restricted to phenomena. Intellect with its pure concepts of substance, cause, possibility, existence, and necessity provides the foundation for the validity of the metaphysics of monads; this science yields an intellectual knowledge of such substances (monads) as they are in themselves, but there is no sensible knowledge of monads. The concepts of matter and body are empirical, sensitive ones belonging to physics but not to metaphysics.

By the time Kant’s thought attained full maturity in the Critique of Pure Reason, the pure concepts of substance, cause, possibility, existence, and necessity had become coterminous with the two pure forms of intuition, space and time, in having a valid application to nothing but phenomena. The intelligible world of monads, conceived in the Dissertation as a known realm of things-in-themselves, becomes in the Critique unknowable realm of noumena underlying the knowable realm of Phenomena. One has a detailed and actual knowledge of matter and body but only a problematic knowledge of monads and noumena. The noumena did not wither away completly in the idealist like Berkeley or a phenomenalist like Hume. Rather, Kant was a type of realist not unlike Descartes or Locke in his claim that appearances are not all that there is but are all that one has an actual and detailed knowledge of. There is a reality behind the appearance, but one has only a problematic concept of this reality. He often characterized this position of the Critique as transcendental idealism in order to distinguish this brand of idealism from the extreme form typified by Berkeley.

And so matter can be defined, in most general terms, as an appearance given in space. When one turns to a more particular characterization of matter, one finds that Kant”s mature theory of matter developed as an opposition to the atomist view of matter held by Newton and the monadist view of matter held by Leibniz. For Newton matter is composed of physical espouse some form of simple realism and doubtless would have held that these atoms would move about in empty space even if there were no sentient beings anywhere to perceive them. The atoms are absolutely impenetrable, and this means that the matter contituting an atom coheres with a force that cannot be overcome by any existing force in nature. Atoms are absolutely homogeneous as to density. They differ from one another only in size and shape. Bodies are aggregates of such atoms and differ in density according to how much empty space, or void, is interspersed among the atoms.

In the “Dynamics” of the Metaphysical Foundations Kant objected to such absolute impenetrability as being an occult quality that no experiment or experience whatsoever could substantiate. We have seen earlier what Kant thought about absolute, empty space. Newton thus regarded matter as an interuptum. So also did Kant in his early work entitled Physical Monadology (1756). But in the Critical thought of the Metaphysical Foundations, he rejected all forms of atomism and monadology. He maintained that matter is a continuum, as we shall see.

Motive forces were for him the fundamental attributes of matter, a position which he held even in the days of the Physical Monadology. By contrast, Newton had taken a different view on the relation between forces and matter. For him atoms are inert but mobile. Since inertia is an entirely passive property of the atoms, they must be moved by an active principle external to them. God is the ultimate cause of gravitational motion by virtue of His acting through the immaterial medium of absolute space, as one can infer from various scholia in the Principlia and queries in the Opticks. Accordingly, Newton did not regard attraction (as Kant did) as a basic property of matter itself. For Kant only two kinds of moving forces are possible: repulsive and attractive. If two bodies (regarded as mathematical points) are being considered, then any motion which the one body can impress on the other must be imparted in the straight line joining the two points. They either recede from one another or approach one another; there are no other possibilities. Since forces are what cause bodies to move, the only kinds of forces are therefore repulsive and attractive.

When one body tries to enter the space occupied by another body, the latter resists the intrusion and the former is moved in the opposite direction. The repulsive (or expansive) force exerted here is also called elastic. For Kant all matter is originally elastic, infinitely compressible but impenetrable—one body cannot compress another to the extent that the first occupies all the space of the second. He called such elasticity. “relative impenetrability” and contrasted it with the absolute impenetrability posited by atomism. The relative kind has a degree that can be ascertained by experience—for instance, gold is more penetrable than iron—whereas the absolute kind is open to no experience whatsoever. On the atomic theory, bodies are compressed when the empty space among the atoms constituting bodies is eliminated and the atoms stand tightly packed. But once so packed, they admit of no further compression.

Unless there were another force acting in an opposite direction to repulsion, that is, acting for approach, matter would disperse itself to infinity. By means of universal attraction all matter acts directly on all other matter and so acts at all distances. This force is usually called gravitation, and the endeavor of a body to move in the direction of the greater gravitation is called its weight. If matter possessed only gravitational force, it would all coalesce in a point. The very possibility of matter as an entity filling space in a determinate degree depends on a balance between repulsion and attraction. Sensation makes us aware of repulsion when we feel or see some physical object and ascertain its size, shape, and location. Repulsion is directly attributed to matter. Attraction is attributed to matter by inference, since gravitation alone makes us aware of no object of determinate size and shape but reveals only the endeavor of our body to approach the center of the attracting body.

True attraction is action at a distance. The earth attracts the moon through space that may be regarded as wholly empty. And so gravity acts directly in a place where it is not. Descartes and others thought this to be a contradictory notion and tried to reduce all attraction to repulsive force in contact. Attraction is therefore nothing but apparent attraction at a distance. Descartes propounded the theory of a plenum with fourteen vortices to account for the celestial motions of the planets about the sun and the moons about the planets. Newton objected to such plenum and vortices because he thought that the friction between the celestial bodies and this hypothesized swirling fluid medium would slow down the celestial motions and eventually terminate them. He, like Kant, espoused a true attraction rather than an apparent one.

If Kant had ever critically examined Newton’s suggestions as to the ultimate cause of gravitation, he doubtless would have had emphatic objections. He showed in the Critique of Pure Reason that God’s existence cannot be established by theoretic reason. For him attraction is a property of matter itself. He argued against Descartes’s apparent attraction by pointing out that such attraction operates by means of the repulsive forces of pressure and impact so as to produce the endeavor to approach, just as in the case when one billiard ball approaches another after the first has been hit by a cue. But there would not even be any impact or pressure unless matter cohered in such a way as to make such impact and pressure possible. Matter would disperse itself to infinity if it possessed nothing but repulsive force. Hence there must be a true attraction acting contrary to repulsion in order for impact and pressure to bring about even apparent attraction.

Thus matter in general was reduced by Kant to the moving forces of repulsion and attraction. He appealed to these forces to account for the specific varieties of matter. Attraction depends on the mass of the matter in a given space and is constant. Repulsion depends on the degree to which the given space is filled; this degree can vary widely. For example, the attraction of a given quantity of air in a given volume depends on its mass and is constant, while its elasticity is directly proportional to its temperature and varies accordingly. This means that repulsion can, with regard to one and the same attractive force, be originally different in degree in different matters. Consequently, a spectrum of different kinds of matter each having the same mass (and therefore having the same attraction) can vary widely in repulsion—running, for instance, from the density of osmium to the rarity of the ether. And so every space can be thought of as full and yet as filled in varying measure.

Kant claimed that matter is continuous quantity involving a proportion between the two fundamental forces of attraction and repulsion. For an atomist like Newton matter is discrete quantity, and the force of attraction in his theory is superadded through the agency of God. The varying densities of elements and compounds of matter are for Newton a function of the amount of empty space interspersed among the atoms. Empty space, according to Kant, is a fiction that can be discerned by no sense experience whatever. The senses reveal to us only full spaces. Kant’s theory of matter committed him to accept the existence of an ether.

The ether was mentioned in many of his writings. In his doctoral dissertation, entitled A Brief Account of Some Reflections on Fire (1755), Kant said in proposition VIII that the matter of heat (or the caloric) is nothing but the ether (or the matter of light) which is compressed within the interstices of bodies by means of their strong attraction. In the Metaphysical Foundations of Natural Science he accepted the existence of the ether cautiously, as a hypothesis that he found more plausible than the atomists’ hypothesis of the reality of absolutely impenetrable atoms and absolutely empty space. Toward the end of chapter 2 the ether is characterized as a matter that entirely fills space, leaving no void. It is so rarefied that it fills its space with far less quantity of matter than any of the bodies known to us fill their spaces. In relation to its attractive force the repulsive force of the ether must be incomparably greater than in any other kind of matter known to us.

Between 1790 and 1803 Kant worked on what is now called the Opus postumum. At his death this unfinished work survived as a stack of handwritten pages, which were eventually gathered by editors into thirteen fascicles (Convoluten). Sections of it constitute coherent wholes, others provide illustrations, and still others are repetitions of earlier works. The Opus appears in Volumes XXI and XXII of the Royal Prussian Academy edition of Kant’s works. Part of the Opus contains the Transition From the Metaphysical Foundations of Natural Science to Physics. The theory of the ether figures in almost all parts of the Transition but especially in Convolute X, XI, and XII of the Opus. There the ether is characterized as a matter that occupies absolutely every part of space, that penetrates the entire material domain, that is identical in all its parts, and that is endowed with a spontaneous and perpetual motion.

Kant based his proof of the ether’s existence upon the unity of experience. Space, which is unitary, is the form of all experience; hence experience is unitary. Experience is a system made up of a manifold of sense perceptions synthesized in space by the intellect. These perceptions are caused by the actions of the material forces which fill space. Accordingly, the motive forces of matter must collectively be capable of constituting a system in order to conform to the unity of possible experience. Such a system is possible only if one admits, as the basis of these forces, the existence of an ether that has the properties listed above. Therefore, the existence of the ether is the a priori condition of the system of experience. Many critics have found this proof unconvincing, as well they might. The Transition, as it has come down to us, is merely a series of sketches for a work that was never finished. Accordingly, it suggests about as many unanswered questions as it provides solutions.

Kant in his mature period opposed not only atomism but also all forms of monadology. He was like Leibniz and unlike Newton in that he put the emphasis, both in his youth and in his maturity, on force rather than on atomic particles of impenetrable mass. In the Physical Monadology (1756) he even claimed (following Leibniz) that bodies are composed of monads, which are indivisible, simple substances. The space which bodies fill is infinitely divisible and is not composed of original, simple parts because space does not have any substantiality; it is only the appearance of the external relations bound up with the unity of the monad. So conceived, the infinite divisibility of space is not opposed to the simplicity of monads. Matter is not infinitely divisible, while space is. But by the time his thought had arrived at the critical phase represented by the Critique of Pure Reason and the Metaphysical Foundations, Kant had repudiated both the view (derived from Leibniz) that bodies are composed of monads and the view (espoused by Leibniz) that space is a relation among monads. Perceptible matter was now continuous quantity, and space was a form of sensible intuition. What did he think now about the infinite divisibility of matter and space? One must turn to the Second Antinomy in the “Dialectic” of the Critique and the “Dynamics” of the Metaphysical Foundations to learn the answer.

The outcome of these discussions is this: Matter as appearance is infinitely divisible and therefore consists of infinitely many parts, but matter as appearance does not consist of the simple (either atoms or monads); matter as thing-in-itself does not consist of infinitely many parts (either atoms or monads), but matter as thing-in-itself does consist of the simple. It was pointed out earlier that according to Kant’s position of transcendental idealism, we have actual cognition of things as appearances and a problematic concept of the reality behind the appearance. Accordingly, matter can be regarded as appearance or as the reality (thing-in-itself) behind the appearances.

Intuitive space is divisible to infinity. Any matter filling such space is also divisible to infinity. But this means that matter as appearance is infinity. But this means that matter as appearance is infinitely divisible; it does not mean that matter as thing-in-itself consists of infinitely many parts (as an atomist or a monadist might claim). Only the division of the appearance can be infinitely continued, not the division of the thing-in-itself. Any whole as thing-in-itself must already contain all the parts into which it can be divided. But the division process can never be finished. And so the thought that matter as thing-in-itself contains infinitely many parts is self-contradictory.

Furthermore, it cannot be maintained that matter as appearance is made up of the simple. The composite of things-in-themselves must consist of the simple, since the parts must be given before all composition. But the composite in the appearance does not consist of the simple, because an appearance can never be given in any way other than as composite (extended in space); its parts can be given only through the process of division, and therefore not before the composite but only in it (and thus the atomist and monadist are foiled again).

Even though matter as appearance is mathematically divisible into infinitely many parts, no real distance of parts is to be assumed. Physicists usually represent the repulsive forces of the parts of elastic matters (for instance, a gas) when these matters are in a state of greater or lesser compression as increasing or decreasing in a certain proportion to the distance of their parts from one another. This is necessary for the mathematical construction of the concept corresponding to such a state of elastic matters; in this construction all contact of parts is represented as an infinitely small distance. The Posited spatial distance of the parts should be understood, however, as nothing but a mathematical convenience, necessary convenience though it is. In reality, matter is continuous quantity, and there is no spatial distance between its parts; they are always in contact.

Time, space, matter, force—Kant’s views on these fundamental concepts of natural science have now been examined; but motion has not yet been considered in any detail. In contrast with Newton, Kant claimed in the “Phenomenology” of the Metaphysical Foundations, as well as in the earlier New Conception of Motion and Rest (1758), that all motion is relative. The motion of a body is the change of its external relations to a given space. If a ball rolls on a table top, it changes its position relative to various points on the top. But we have the same change of positions if the ball remains at rest and the table moves under it in the opposite direction with the same velocity. Hence the rectilinear motion of a body with regard to an empirical space can be viewed as either the body moving by reference to the space at rest or as thebody at rest and the space moving relative to it. It is impossible to think of a body in rectilinear motion relative to no material space outside of it. Matter can be thought of as moved or at rest only in relation to matter and never by reference to mere space without matter. Furthermore, there is no fixed empirical point by reference to which absolute motion and absolute rest can be determined. The center of the sun might be fixed as the center of our solar system, but our solar system moves relative to other solar systems in the Milky Way, and the Milky Way moves relative to other galaxies, and so on.

Accordingly, there is no empirical space defined by matter that can provide a reference system for all possible rectilinear motions of bodies in the universe. Therefore, all motion or rest is merely relative, and neither is absolute. But the empirical space (for instance, the table top) in relation to which a body (for instance, the ball) moves or remains at rest must itself be referred to another (absolute) space at rest within which this given empirical space is movable. If one did not invoke such immovable, absolute space, one would be claiming that the given empirical space isimmovable and hence absolute; but by experience all material spaces are movable. This ultimate absolute space by reference to which all empirical spaces are movable (and hence relative) exists merely in thought and not in fact, since only empirical (material) spaces actually exist. But such absolute (immovable, immaterial) space is nevertheless a necessary idea that serves as a rule for considering all motion therein as relative. Everything empirical is movable in such ideal absolute space; and all such motions in it are valid as merely relative to one another, while none is valid as absolute. And so the rectilinear motion of a body in relative space is reduced to absolute space when one thinks of the body as in itself at rest but thinks of the relative space as moved in the opposite direction in absolute space.

The circular motion of a body might seem, at first glance, to be an absolute motion. In contrast with the foregoing case of rectilinear motion, it is not all the same whether the earth is regarded as rotating on its axis while the heavens remain still (Copernicus) or the earth is regarded as staying still while the heavens rotate about it (Ptolemy). Both give the same appearance of motion. But the former case is the true one, while the second one is false. To prove that the earth rotates, Kant says that if one puts a stone at some distance from the surface of the earth and drops it, then the stone will not remain over the same point of the earth’s surface in its fall but will wander from west to east. Accordingly, the rotation of the earth on its axis (or the rotation of any other body) is not to be represented as externally relative. But does this mean that the motion is absolute? Even though circular motion exhibits no real change of place with regard to the space outside of the rotating body, such motion does exhibit a continuous dynamic change of the relation of matter within its space. If the earth were to stop spinning, it would contract in size. The present size of the earth involves a balance between centrifugal forces and attracting ones. Hence the actuality of the earth’s rotation rests upon the tendency of the parts of the earth on opposite sides of the axis of rotation to recede from one another. The rotation is actual in absolute space, since this rotation is referred to the space within, and not to that outside of, the rotating body. And so rotation is not absolute motion but is a continuous change of the relations of matters (or parts of the rotating body) to one another; this change is represented in absolute space (the space within the rotating body), and for this reason such change is actually only relative motion.

The case of the translation of body relative to a material reference system and the case of a rotating body have now been considered. What about the third and last case, in which one body hits another? Is this motion absolute? In this case both the matter and the (relative) space must necessarily be represented as moved at the same time: in every motion of a body whereby it is moving with regard to another body, an opposite and equal motion of the other body is necessary. One body cannot by its motion impart motion to another body that is absolutely at rest; this second body must be moved (together with its relative space) in the opposite direction with just that quantity of motion which is equal to that quantity of motion which it is to receive through the agency of the first body and in the direction of this first one. Both bodies, subsequently, put themselves relative to one another—that is, in the absolute space lying between their two centers—in a state of rest. But with reference to the relative space outside of the impacting bodies, the bodies move after impact with equal velocity in the direction in which the first body is moving. This same law holds if the impact involves a second body that is not at rest but moving. There is no absolute motion in this third case, even though a body in absolute space is thought of as moved with regard to another body. The motion in this case is relative not to the space surrounding the bodies but only to the space between them. When this latter space is regarded as absolute, it alone determines their external relation to one another. And so this motion is merely relative.

In the case of rectilinear motion, the change of place may be attributed either to the matter (that is, space at rest and matter moving with respect to it) or to the space (that is, matter at rest and space moving with respect to it). In the case of rotatory motion, the change of place must be attributed to the matter. In the case of colliding bodies, both the matter and the (relative) space must necessarily be represented as moved at the same time. Motion is relative in all three cases by reference to absolute space: in the first case by reference to absolute space outside of the body, in the second to absolute space inside of the body, and in the third to absolute space between two bodies.

In a pre-Critical work entitled Universal Natural History and Theory of the Heavens (1755) Kant was much more favorably disposed toward Newton than he was in his mature period. In fact, the full title of the work has this addition: An Essay on the Constitution and Mechanical Origin of the Whole Universe Treated According to Newtonian Principles. In this book Kant went far beyond anything that is to be found in Newton’s own writings. Newton aimed at nothing more than describing and explaining the regularities that exist in the world in its present state of evolution. He paid special attention to the regularities of the planets and their motions around the sun, but nowhere did he try to explain, on the basis of his own mechanical principles, how the solar system originated and reached its present state of uniformity. In his Theory of the Heavens, Kant, by a series of bold strokes, anticipated astronomical facts that were later confirmed by very powerful observational techniques and with the help of relativistic cosmological theory. He conjectured that our solar system is a part of a vast system of stars making up a single galaxy, that the so-called nebulous stars are galactic systems external to but similar to our own galaxy (a fact that was not confirmed until the twentieth century), and that there are many such galaxies making up the universe as a whole. Much of this thought was stimulated by the work of an Englishman, Thomas Wright of Durham, entitled Original Theory or New Hypothesis of the Universe (1750).Kant read an abstract of this book in a Hamburg newspaper of January 1751. Wright gave the first essentially correct interpretation of the Milky Way and suggested that the nebulae are systems of stars much like our own galaxy. Newton provided Kant with the fundamental physical principles to help him in the development of his cosmogony, while Wright gave suggestions for working out the particulars of the spatial organization of the main components of the universe as a whole.

At this pre-Critical stage Kant claimed that the world had a beginning in time and is infinite in spatial extent. The universe came into existence through an act of creation on the part of a transcendent deity. In the Critique of Pure Reason these claims were presented as unresolvable antinomies. In the First Antinomy the thesis claims that the world has a beginning in time and is also limited spatially, while the antithesis claims that the world has no beginning and is not limited spatially. In the Fourth Antinomy the thesis claims that an absolutely necessary being belongs to the world as its part or as its cause, while the antithesis claims that no absolutely necessary being exists anywhere in the world, nor does such a being exist outside the world as its cause. However, in his Universal Natural History and Theory of theHeavens, Kant adopted the theistic view (espoused also by Newton and Leibniz) that the cosmos as a whole owes its genesis to a Mosaic deity.

But once God had created time, space, and matter and had endowed them with the very laws that Newton eventually discovered, how did the universe evolve? The term “natural history” in the title of the work indicates that Kant was interested in an evolutionary account of the universe. On this subject he made suggestions that resemble those later set forth by Laplace. Kant claimed that the planets of our solar system arose ffom the condensation of primordial diffused matter. This position contrasts with one claiming that some celestial body passed near our sun and set up cataclysmic actions that caused the planets to be born of our sun through the agency of tidal forces. For Kant the sun, the planets, and their moons all originated by a process of condensation of a diffused mass of widely distributed, thin matter (or, in other words, a nebulous mass of matter). He appealed to the Newtonian attraction and repulsion of the various material particles of the original nebulous mass as being the causes of the solar system’s flattening out into a disk. Other astronomical systems in the universe developed in a similar way.

On Kant’s view the universe is not a static mechanism; it undergoes a fundamental change. Various regions of the universe undergo cyclical changes, being born as just described and dying when the train of planets associated with each star tends to run down and eventually falls back into its respective sun. The sun then heats up with this new matter and eventually explodes into a nebular cloud of matter. Our own developed world is midway between the ruins of the nature that has been destroyed and the chaos of the nature that is still unformed. He claimed that this Phoenix of Nature burns itself only in order to revive from its ashes in restored youth through all the infinity of times and places.

Cosmological theory has made great advances since Kant’s day, but his theory has nonetheless inspired proponents of recent theories. C. F. von Weizsäcker, in his History of Nature (1949) and again in his Gifford lectures for 1959–1960 (entitled The Relevance of Science), has espoused the view that the planets of our solar system were formed from a nebula that surrounded the sun. G. Kuiper of Yerkes Observatory thinks that some denser parts of the nebula condensed further under the influence of their own gravity—the very view that Kant advanced. Kant has also been the object of much criticism. The claim has been made by many that he put forth bold conjectures before the experimental evidence was in and that he even twisted some evidence that was in so that it would conform with his theories. Perhaps he did make too many bold conjectures; but if such conjectures were never made, would science ever make much progress? In his Theory of the Heavens, Kant borrowed the principles of Newton’s system of the world and by a sort of thought experiment used them to extend and deepen man’s picture of the universe. It is a wonder that his though experiment turned out to be so close to much of subsequent cosmological theory.

In the middle of the preface to the Theory of the Heavens, Kant said that it would be possible to grasp the origin of the whole present constitution of the universe by means of mechanical (efficient) causes before it would be possible to grasp the production of even a single herb or a caterpillar by means of mechanical causes alone. He did not categorically deny the possibility that organisms might some day be completely explained mechanically. But in the Critique of Teleological Judgment (1790), Kant did deny the possibility of such an explanation. All the phenomena of inanimate nature can be explained in terms of the motion of matter in space and enduring through time, while for living things such efficient causes are not enough—they must be explained in terms of an end and thus require final causes in addition to efficient ones. In more modern terms, biology, for Kant, cannot in the final analysis be explained solely in terms of physics and chemistry.

Kant was opposed to the Cartesian conception of animal machines; no one can or ever will be able to produce a caterpillar from a given bit of matter. An organism exists as a physical end and is both cause and effect of itself. The parts of an organism, both in their existence and in their from, are possible only by their relation to the whole; furthermore, the parts combine spontaneously to constitute the unity of a whole by being reciprocally cause and effect of their form. A machine has only motive power, while an organized being possesses inherent formative power, which it imparts to raw materials devoid of form.

An oak tree, for example, prepares the matter that it assimilates; and it bestows upon this matter a specifically distinctive quality which mere mechanical nature cannot supply. The tree develops itself by means of a material which the tree itself produces through an original capacity to select and construct the raw material that it derives from nature outside of it. It is as though the tree were itself a supremely ingenious artisan in the building of itself, and the subjunctive mood must be emphasized here. One cannot claim that there really is an end in the thing that is operating in its production; to do so would be to foist an unprovable anthropomorphism on organisms. A person coughs when some water goes down his windpipe while he is taking a drink. Substances heavier than air trigger the coughing mechanism. Such a mechanism is said to have adaptive significance for the organism, in that it enables the organism to live. But it cannot be said that the cough mechanism is intended to keep the organism alive, except on an analogy with artistic production. Final causes are merely regulative concepts which human beings use to comprehend biological organisms, which differ essentially from inorganic entities. One deals with them by means of an analogy with artifacts; it is as though a tree organized itself in a way not unlike the way an artisan forms his product.

Finality is read into the facts, and teleological principles are nothing but heuristic maxims whose justification resides in their fruitfulness in providing systematic comprehension of living organisms. When finality is so viewed, the question of whether, in the unknown inner basis of nature itself, efficient causes and final ones may cohere in a single principle is left open. Accordingly, teleology and mechanism in no way contradict one another, as Kant explains with the greatest epistemological subtlety in §77 of the Critique of Teleological Judgment. Efficient causes are concepts that determine (and do not merely regulate) our knowledge of phenomena. Therefore, the investigations of biology must be pushed as far as possible in the direction of efficient causes; the simple mechanism of nature must be the basis of research in all investigation of biological phenomena. But this does not mean that such phenomena are possible as entities solely on the basis of efficient causation. The principle of teleology directs one to continue research as far as possible on the basis of efficient causation. The processes of digestion are not understood by any appeal to the principle that such processes enable the organism to live and thrive. Such processes are understood by accounting for the passage of chemical substances through membranes, but why such membranes permit the passage only of certain chemical substances and no others may not be able to be accounted for on the basis of mechanical causes alone.

Efficient causes are progressive, while final causes are reciprocal. In the former the connection constitutes a series (the so-called causal chain) which is always such that the things which, as effects, presuppose other things as their causes cannot themselves also be causes of these other things. Final causes are that the series involves regressive as well as progressive dependency (a house is the cause of one’s receiving rent money, but the house was built in the first place so that one might receive such rent). Kant calls efficient causes a nexus of real ones and final causes a nexus of ideal ones. The former are also said to determine our knowledge of phenomena. He treats of efficient causation in the Second Analogy of Experience in the “Transcendental Analytic” of the Critique of Pure Reason, where he distinguishes between a subjective connection of cognitions and an objective connection of them. One walks into a warm room and sees a glowing stove. As far as the subjective order of cognitions is concerned, one first feels warm and only later spies the stove concealed behind a screen in the corner. But yet one says that it is the stove which causes the room to be warm and not that it is the warm room which causes the stove to glow. In order to have knowledge through perceptions, one must connect them in their objective time relations. There is no necessity in the subjective order of congnitions, but there certainly is in one’s synthetic reorganization of that order. If event A (glowing stove) precedes event B (warm room) objectively, then one must think of A as preceding B or else be wrong. It makes no difference whether one perceives A first and then B, or B first and then A in his subjective consciousness.

Kant worked out his theory of efficient causation largely in opposition to Hume’s position on the subject. Hume claimed that there are three conditions which two events must fulfill in order for one event to be considered the cause of another: the cause precedes the effect in time, cause and effect are contiguous in space, and cause and effect are found constantly conjoined in experience. Kant leveled his attack mainly against the third condition, but other people have found objections to the first two conditions as well. In the realm of colliding billiard balls, the cause does temporally precede the effect; but in the case of boiling water, the boiling occurs just when the water reaches 100° c.; and so cause and effect are simultaneous. As for spatial contiguity, the moon through empty space attracts the waters of the earth’s seas and oceans to produce tides. In the case of such action at a distance, there is no contiguity in space. As for constant conjunction, some have pointed out that night and day are always conjoined, but night is not the cause of day. Kant objected to the third condition by claiming that on Hume’s view there is no way to distinguish the subjective order of cognitions from the objective order of them.

Hume held that the idea of necessary connection between cause and effect arises when we develop a habit of association from a repeated subjective succession of perceptions (fire always burns). He thus based causation entirely on sensible experience. In contrast, Kant claimed that the objective reordering of the subjective succession of cognitions (which is based on sense perception and imagination) is actually a synthetic reorganization of the a posteriori order of perception. This synthetic reorganization is an a priori act of the human understanding. In other words, the causal ordering of cognitions is an act of the intellect that is brought to experience (or, even better, that makes experience) and is not an ordering derived from experience (as Hume claimed). For Kant in his Critical period the pure concepts of substance, cause, possibility, existence, and necessity were a priori concept that are coterminous with the pure forms of intuition, time and space. Experience is the result of the synthetic activity of the intellect by means of such pure concepts in organizing empirically given sense perceptions that are arrayed in time and space. The history of theories of efficient causation did not end with Kant. The controversy between the a posteriori and a priori views broke out again in the middle of the nineteenth century with the debates between John Stuart Mill and William Whewell. Mill disagreed with Kant, while Whewell agreed. In the twentieth century Bertrand Russell and A. C. Ewing have continued teh debate.

Time, space, matter, force, motion, cause—the major portions of Kant’s philosophy of science have now been examined in terms of these key concepts. This philosophy is rationalistic in comparison with the views of such a later thinkers as Mill and Russell but seems almost empiricistic in comparison with such of Kant’s immediate German idealist successors as Fichte, Schelling, and Hegel. According to Kant, the human mind supplies the form of experience (time, space, and the categories of the understanding); but the content of experience is empirically given in sensation from a source outside the human self (the real material world). The German idealists claimed that the self is the source not only of the form of experience but also of its content. On this view nature becomes a sort of external symbol or image of the self. Nature is the self taken as object. Accordingly, Schelling thought that the whole of physics could be spun out of the mind itself. If so, what need is there for experiment?

The accusation of armchair scientist which Erich Adickes leveled at Kant might more appropriately be directed against these Romantic idealists. Apart from the most general, formal aspects of nature (matter is a continuum and not an interruptum, there is no absolute motion, the changes in nature are causally connected, and so on), all the rest of nature in its particular aspects (temperature of Venus, strength of the gravitational pull of the moon, the cause of diabetes, and so on) must for Kant be learned by experiment. To be sure, he was more interested in the formal aspects than in the particular, but he never claimed that the particular aspects could be dealt with in any way other than by observation and experiment.

The Kantian emphasis on causality in conformity with law and on mathematical rigor in conformity with experience, contributed important elements to the philosophical depth and seriousness that animated the German scientific movement from the middle of the nineteenth century on and that distinguished it from the scientific traditions of other cultures. Two quotations from classic texts will lllustrate the way in which creative German scientists formed their expectations of what a scientific explanation does from their knowledge of Kant. The first, concerning physics, is from Helmholtz’s Ueber die Erhaltung der Kraft (1847), the famous memoir on the conservation of energy which in its philosophical aspect Helmholtz attributed expressly to Kant’s inspiration:

The final goal of the theoretical natural sciences is to discover the ultimate invariable causes of natural phenomena. Whether all processes may actually be traced back to such causes, in which case nature is completely comprehensible, or whether on the contrary there are changes which lie outside the law of necessary causality and thus fall within the region of spontaneity or freedom, will not be considered here. In any case it is clear that science, the goal of which is the comprehension of nature, must begin with the presupposition of its comprehensibility and proceed in accordance with this assumption until, perhaps, it is forced by irrefutable facts to recognize limits beyond which it may not go [from Selected Writings of H. L. F. von Helmholtz, Russell Kahl, ed.(Middletown, Conn., 1971), p. 4].

The second quotation, concerning biology, is from Schwann’s Mikroskopische Untersuchungen über die Uebereinstimmung in der Struktur und dem Wachstume der Tiere und Pflanzen (1839), the equally famous treatise concerning the cellular structure of the living organism. It concludes with a regulatory discussion of methodology deriving from the Kantian distinction between mechanistic and teleological explanation in the Critique of Teleological Judgment;

Teleological views cannot be discarded for the time being since not all phenomena are to be clearly explained by the physical view. Discarding them is not necessary, however, for a teleological explanation is admissible if and only if a physical explanation can be shown to be unattainable. Certainl y it brings science closer to the goal to try at least to formulate a physical explanation. I should like to repeat that when I speak of a physical explanation of organic phenomena, I do not necessarily mean that an explanation in terms of known physical forces like that universal resort, electricity, is to be understood, but rather an explanation in terms of forces which operate like physical forces in service to strict laws of blind necessity, whether or not such forces be found in inorganic nature [Ostwalds Klassiker der Exacten Wissenschaften (Leipzig, 1910), p. 187].

In general, it was in service to the rigorous idealism of Kant that leaders of the first great geneation of German science–including Müller. Schleiden, Mayer, du Bois-Reymond, and Virchow—repudiated the literary and speculative Naturphilosphie of the Romantic idealists, which they dismissed as an episode of cultural wild oats in the adolescence of the German spirit.

In the twentieth century Kant’s thought has not had the direct influence on experimental scientists that it had earlier on Helmholtz and Schwann. But in the philosophy of science Ernst Cassirer gave a Kantian interpretation of the metaphysical and epistemological foundations of relativity in his Einstein’s Theory of Relativity Considered From the Epistemological Standpoint and of quantum theory in his Determinsism and Indeterminism in Modern Physics. C. F. von Weizsäcker gave a Kantian interpretation of quantum theory in his The World View of Physics.


I. Original Works. The best ed. of Kant’s works is Kants gesammelte Schriften, published by the Royal Prussian Academy of Sciences (Berlin, 1902– ). This ed. already runs to some 27 vols. and, when complete, will contain not only all the published works, letters, and fragments but also all the extant transcripts of lectures.

English translations of some of Kant’s works mentioned in this essay follow, in the order of the publication of the orginal German works: Universal Natural History and Theory of the Heavens, trans. by W. Hastie (Ann Arbor, Mich., 1969), a repr. of Hastie’s Kant’s Cosmogony (Edinburgh, 1900); Kant’s Inaugural Dissertation and Early Writings on Space, trans. by J. Handyside (Chicago, 1929); Critique of Pure Reason, trans. by Norman Kemp Smith, 2nd ed., rev. (London, 1933); Metaphysical Foundations of Natural Sience, trans. by James W. Ellington (Indiana-polis, 1970); Critique of Teleological judgement, trans. nby J. C. Meredith (Oxford, 1928).

II. Secondary Literature. The best biography of Kant is Karl Vorländer, Immamuel Kant, der Mann und das Werk, 2 vols. (Leipzig, 1924). The best in English is J. W. H. Stuckenberg, The life of Immamuel Kant (London, 1882).

The literature about Kant is enormous. Erich Adickes, “Bibliography of Kant,” in The Philosophical Review (1893), lists 2,832 titles and goes only to 1802. The Literaturzeichnisse preceding Kant’s various writings on science and the philosophy of science that are in vol. VII of Karl Vorländer’s ed. of King’s works in the Philosophische Bibliothek series, entitled Kants sämtliche Werke, 10 vols. (Leipzig, 1913–1922), are recommended for books specifcally on King’s works on sciene and the philosophy of science.

A brief list of the works especially relevant to this essay is Erich Adickes, Kants Opus postumum, which is KantStudien, supp. vol. no.50 (Berlin, 1920); and Kant als Naturforscher, 2 vols. (Berlin, 1924–1925); Ernst Cassirer, Substance and Function and Einstein’s Theory of Relativity (Chicago, 1923), pp. 347–456; and Determinism and Indeterminism in Modern Physics (New Haven, 1956); James W. Ellington, introduction and supplementary essay entitled “The Unity of Kant’s Thought in His Philosophy of Corporeal Nature,” in the trans. of the Metaphysical Foundations of Natural Science (see above); Irving Polonoff, Force. Cosmos, Monads, and Other Themes of Kant’s Early Thought, which is Kant-Studien, supp. vol. no. 106 (Bonn, 1972); Lothar Schäfer, Kants Metaphysik der Natur (Berlin, 1966); and C. F. von Weizsäcker, The World View of Physics (Chicago, 1952); and The Relevance of Science (London, 1964).

James W. Ellington

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Immanuel Kant

Immanuel Kant

The major works of the German philosopher Immanuel Kant (1724-1804) offer an analysis of speculative and moral reason and the faculty of human judgment. He exerted an immense influence on the intellectual movements of the 19th and 20th centuries.

The fourth of nine children of Johann Georg and Anna Regina Kant, Immanuel Kant was born in the town of Königsberg on April 22, 1724. Johann Kant was a harness maker, and the large family lived in modest circumstances. The family belonged to a Protestant sect of Pietists, and a concern for religion touched every aspect of their lives. Although Kant became critical of formal religion, he continued to admire the "praiseworthy conduct" of Pietists. Kant's elementary education was taken at Saint George's Hospital School and then at the Collegium Fredericianum, a Pietist school, where he remained from 1732 until 1740.

In 1740 Kant entered the University of Königsberg. Under the influence of a young instructor, Martin Knutzen, Kant became interested in philosophy, mathematics, and the natural sciences. Through the use of Knutzen's private library, Kant grew familiar with the philosophy of Christian Wolff, who had systematized the rationalism of Leibniz. Kant accepted the rationalism of Leibniz and Wolff and the natural philosophy of Newton until a chance reading of David Hume aroused him from his "dogmatic slumbers."

The death of Kant's father in 1746 left him without income. He became a private tutor for 7 years in order to acquire the means and leisure to begin an academic career. During this period Kant published several papers dealing with scientific questions. The most important was the "General Natural History and Theory of the Heavens" in 1755. In this work Kant postulated the origin of the solar system as a result of the gravitational interaction of atoms. This theory anticipated Laplace's hypothesis (1796) by more than 40 years. In the same year Kant presented a Latin treatise, "On Fire", to qualify for the doctoral degree.

Kant spent the next 15 years (1755-1770) as a nonsalaried lecturer whose fees were derived entirely from the students who attended his lectures. In order to live he lectured between 26 and 28 hours a week on metaphysics, logic, mathematics, physics, and physical geography. Despite this enormous teaching burden, Kant continued to publish papers on various topics. He finally achieved a professorship at Königsberg in 1770.

Critique of Pure Reason

For the next decade Kant published almost nothing. But at the age of 57 he published the first edition of the Critique of Pure Reason (1781; 2d ed. 1787). This enormous work, one of the most important and difficult books in Western thought, attempts to resolve the contradictions inherent in perception and conception as explained by the rationalists and empiricists.

On the level of experience, Kant saw the inherent difficulties in the "representative theory of perception." Our percepts, or intuitions of things, are not themselves objects but rather images or re-presentations. Since these perceptual images are the only evidence for an external, physical world, it can be asked how faithfully mental images represent physical objects. On the level of conception, mathematical, scientific, and metaphysical judgments make predictions about the connections and consequences of events. As these judgments tell us about the past, present, and future, they cannot be derived from our immediate experience. Some events, however, can be experienced as conforming to these universal and necessary laws; hence, these judgments are more than mere definitions. The aim of the critique is to explain how experience and reason interact in perception and understanding.

Philosophers had long recognized two kinds of judgment. The first is analytic, which is the product of the analysis or definition of concepts. All analytic propositions are reducible to statements of identity, that is, they define what a thing is. For example, a triangle is a three-sided figure universally (always) and necessarily (could not be otherwise) by definition. As such, all analytic judgments are true a priori, or independent of experience. The content and form of the second type of judgment is exactly the reverse. Synthetic propositions expand or amplify our knowledge, but these judgments are a posteriori, or derived from experience.

Kant's position is that of the first thinker to posit the problem of pure reason correctly by isolating a third order of judgment. Consider the following propositions: 10 times 2 is 20; every event has a cause; the universe is created. As universal and necessary, all three judgments are a priori but also, according to Kant, synthetic, in that they extend our knowledge of reality. Thus the fundamental propositions of mathematics, science, and metaphysics are synthetic a priori, and the question that the Critique of Pure Reason poses is not an analysis of whether there is such knowledge but a methodology of how "understanding and reason can know apart from experience."

The solution to this problem is Kant's "Copernican Revolution." Until Copernicus hypothesized that the sun was the center of the universe and the earth in its rotation, science had assumed the earth was the center of the universe. Just so, argues Kant, philosophers have attempted and failed to prove that our perceptions and judgments are true because they correspond to objects. "We must therefore make trial whether we may not have more success…ifwe suppose that objects must conform to our knowledge." This radical proposal means that the mind constitutes the way the world appears and the way in which the world is thought about.

But, unlike later idealists, Kant does not say that the mind creates objects but only the conditions under which objects are perceived and understood. According to Kant, "we can know a priori of things only what we ourselves put into them." The attempt to preserve a realist orientation leads Kant to distinguish between the appearances of things (phenomena), as conditioned by the subjective forms of intuition, and the categories of the understanding and things-in-themselves (noumena). In brief, mathematics and science are true because they are derived from the ways in which the mind conditions its percepts and concepts, and metaphysics is an illusion because it claims to tell us about things as they really are. But since the mind constitutes the appearances and their intelligibility, we can never know noumenal reality (as it exists apart from mind) with any certainty. Although Kant considers the denial of metaphysics inconsequential because it has consisted only of "mock combats" in which no victory was ever gained, he is at some pains to establish that the restriction of pure reason to the limits of sensibility does not preclude a practical knowledge of morality and religion. In fact, the limitation of pure reason makes such faith more positive.

The first critique attempts to reconcile the conflict between rationalism and empiricism over the role of experience. Kant's ingenuity is to suggest that both parties are correct but one-sided, that is, "though all knowledge begins with experience it does not follow that it arises out of experience." Kant attempts to isolate the a priori element in the various parts of knowledge: intuition, which Kant calls esthetic, understanding, or analytic and speculative reason, or dialectic. He calls his method "transcendental" as opposed to formal or material logic, and by this he means only the manner, or mode, in which we perceive, understand, or think.

The problem of the transcendental esthetic can be seen in the term "a priori intuition." That is, what does the mind tell us about experience prior to having experience. Kant argues that if one eliminates the content of any possible intuition, space and time remain as the a priori forms, or ways, in which the mind can perceive. As a priori forms of any possible experience, space and time are subjective conditions or limitations of human sensibility. But as the universal and necessary conditions without which there will be no experience, these forms are empirical conditions of appearances, or phenomena. Thus, for Kant, space and time are "transcendentally ideal" and "empirically real" as subjective conditions and objective, constitutive principles of intuition. In brief, this is Kant's resolution of the scientific debate between the adherents of Newton's concept of absolute space and time and Leibniz's relational view. Kant is saying that space and time are absolute conditions for human experience even though there may be nonspatial and nontemporal entities that are unknown.

This argument provides an answer to how synthetic a priori judgments in mathematics are possible. These judgments are universal and necessary, and yet they apply to and yield new knowledge about experience. The principle of Kant's explanation may be expressed as follows: whatever is true of a condition is a priori true of the conditioned. Space and time are the conditions for all possible perceptions. And Euclidean geometry and arithmetic are true of space and time. Therefore, arithmetic and geometry are a priori valid for all possible appearances.

A weak analogy with eyeglasses will explain the drift of Kant's thinking. If I cannot see anything without the glasses, they are my subjective limitation since there may be things which are not perceivable. But the glasses are also objective conditions for the possibility of anything appearing to me. And whatevers true of this condition—such as their being tinted—will be true a priori of whatever can be seen but not necessarily of whatever can be. The point of Kant's radical proposal is that human experience may be just that— exclusively human—but that it is valid of appearances since space and time are the a priori and empirical conditions of every possible perception.

A similar explanation of the working of human understanding presented a great difficulty occasioned by the seeming impossibility of specifying the forms of thinking in other than an arbitrary and chance manner. Eventually Kant discovered a "transcendental clue" in the traditional forms of logical judgment enumerated by Aristotle. The question raised is why are there only 12 forms of judgment? Kant argued that each form of possible judgment was related to a thought form that he called an a priori category of the understanding. Thus, again, there is a form and content division such that, if one thinks, there are only certain ways in which one can make judgments about the quantity, quality, relation, and modality of objects. In human understanding, as the name implies, experience is made to stand underneath and be organized by the categories. Experience is given as conditioned by space and time, a category is superimposed by the mind, and the resulting synthesis produces human knowing. This complicated process of synthesis is unified by the ego and aided by the imagination, which associates particular percepts with appropriate universal concepts. As in the case of perception, Kant's efforts are directed toward reconciling the claims of both rationalism and empiricism. Concepts of themselves are empty logical forms, and percepts, alone, are blind; it is only in their synthesis that understanding, or knowing, takes place.

This development commits Kant to the position that science is knowing and metaphysics is false, speculative thinking. Knowing is confirmed by experience as above, but the categories can be extended beyond space and time, and they, then, function as ideas of pure reason. Since metaphysics claims to speak about things as they are rather than as they appear, such pure thinking must justify itself without appeal to experience. But that is just the difficulty when one asks questions about the unconditioned reality of the self, world, or God!

It is not that reason is incapable of producing arguments, but rather that there are equally valid arguments that contradict one another, and experience is unable to resolve these "antinomies," or seeming contradictions. For example, we know that the universe is either created or eternal, and we can think both of these alternatives through; but the spatiotemporal world of experience would be the same in either instance; and so while the mind can think about these problems, it can never know the answers to the questions that it raises. The only exception to this rule occurs in what Kant calls the "dynamical antinomies" concerning the dilemmas of necessity or freedom and atheism or theism. Here Kant suggests that in the realms of morality and religion one can entertain the possibility that while necessity and determinism are true of phenomena, freedom and God are true of noumena. Thus, one could live in a universe that is physically determined and still believe in human freedom.

Later Works

In 1783 Kant restated the main outlines of his first critique in a brief, analytic form in the Prolegomena to Any Future Metaphysics. In 1785 he presented an early view of the practical aspects of reason in Fundamental Principles of the Metaphysic of Morals. In 1788 he published the Critique of Practical Reason.

While theoretical reason is concerned with cognition, practical reason is concerned with will, or self-determination. There is only one human reason, but after it decides what it can know, it must determine how it shall act. In the analytic of practical reason Kant attempts to isolate the a priori element in morality. The notion that happiness is the end of life is purely subjective, and every empirical morality is arbitrary.

Thus the freedom of the will, which is only a speculative possibility for pure reason, becomes the practical necessity of determining how one shall lead his life. And the fundamental, rational principle of a free morality is some universal and necessary law to which a man commits himself. This principle is called by Kant the "Categorical Imperative," which states that a man should obligate himself to act so that any one of his actions could be made into a universal law binding all mankind. The dignity of man consists in the freedom to overcome inclination and private interest in order to obligate oneself to the duty of performing the good for its own sake. In examining the consequences of man's freedom, Kant insists that practical reason postulates the immortality of the soul and the existence of God as the conditions for true freedom.

In 1790 Kant completed his third critique, which attempts to draw these conflicting tensions together. In pure reason the mind produces constitutive principles of phenomena, and in practical reason the mind produces regulative principles of noumenal reality. The Critique of Judgment attempts to connect the concepts of nature with the concepts of freedom. The reflective or teleological judgment of finality, which is derived from our esthetic feelings about the fittingness of things, mediates between our cognition and our will. This judgment neither constitutes nature like the understanding nor legislates action like practical reason, but it does enable us to think of the "purposiveness" of nature as a realm of ends that are in harmony with universal laws.

Although Kant continued writing until shortly before his death, the "critical works" are the source of his influence. Only a life of extraordinary self-discipline enabled him to accomplish his task. He was barely 5 feet tall and extremely thin, and his health was never robust. He attributed his longevity to an invariable routine. Rising at five, he drank tea and smoked his daily pipe and meditated for an hour. From six to seven he prepared his lectures and taught from seven to nine in his own home. He worked in his study until one. He invited friends for long dinners, which lasted often until four. After his one daily meal he walked between four and five so punctually that people were said to set their watches on his passing. He continued to write or read until he retired at ten. Toward the end of his life he became increasingly antisocial and bitter over the growing loss of his memory and capacity for work. Kant became totally blind and finally died on Feb. 12, 1804.

Further Reading

There is no standard edition in English, but virtually all of Kant's major works are available in various paperback editions. The field of general and critical studies is rich. Basic accounts of Kant's critique are Herbert James Paton, Kant's Metaphysic of Experience (2 vols., 1936); Heinrick Cassirer, A Commentary on Kant's Critique of Judgment (1938); A. C. Ewing, A Commentary on Kant's Critique of Pure Reason (1938); Lewis White Beck, A Commentary on Kant's Critique of Practical Reason (1960); Norman Kemp Smith, A Commentary to Kant's Critique of Pure Reason (2d ed. 1962); and S. Körner, Kant (1964), which is one of the best general works available. Specialized studies include Paul Arthur Schlipp, Kant's Pre-critical Ethics (2d ed. 1960); Martin Heidegger, Kant and the Problem of Metaphysics, translated by James S. Churchill (1962); Robert Paul Wolff, Kant's Theory of Mental Activity (1963); and P. F. Strawson, The Bounds of Sense (1966). □

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Kant, Immanuel

Kant, Immanuel

Immanuel Kant, it is said, never traveled more than fifty miles from his native city of Königsberg in East Prussia. Nevertheless, there are few thinkers who have had as wide an influence as Kant in the history of Western thought. His importance for discussions about science and religion stems from his reasoned defense of the position that religion and science should be kept clearly separated from one another.

Life and writings

Born in 1724, Kant was the son of humble pietistic parents who wished for him to have an education. At sixteen he entered the University of Königsberg, where he studied Christian Wolff's interpretation of Gottfried Wilhelm von Leibniz's (16461716) philosophy. Kant's encounter with Isaac Newton's (16421727) work during his student years encouraged in him an independent attitude toward Leibniz's thought, with the additional result that he developed a profound interest in the natural sciences. When his father died during his university training, Kant left the university and served as a tutor in private families near Königsberg between 1748 and 1754. After returning to the university he completed a thesis in June of 1755 and, on finishing a second thesis in September, was granted permission to lecture. Prior to the age of thirty-six, Kant's writings dealt primarily, although not exclusively, with the natural sciences. His most famous work from this period, the Universal Natural History and Theory of the Heavens, was published in 1755 and contained Kant's ideas on the how a cosmos subject to Newton's laws of motion might have formed.

After Kant received a professorship in logic and metaphysics at Königsberg in 1770 it took some time before his writings reflected the turn his appointment marked from a precritical stance to what he himself labeled critical philosophy. Once Kant began publishing, the works came thick and fast. The first edition of his most famous book, the Critique of Pure Reason, did not appear until 1781. When it did so it was largely misunderstood, moving Kant to restate its main arguments two years later in his Prolegomena to Every Future Metaphysics. He also expanded the Critique in a second edition in 1787, and in the following year he published the first of two new critiques, the Critique of Practical Reason. This second critique picked up on a concern with moral philosophy Kant had initially addressed in another work from the 1780s. The Critique of Judgment, which appeared in 1790, dealt with reasoning about the realms of the aesthetic and the purposeful. Earlier in 1786 Kant returned to his reflections on science and its methods in a work entitled The Metaphysical Foundations of Natural Science. Finally, his Religion Within the Boundaries of Pure Reason, which appeared in 1793, provoked King Frederick William II to forbid him from publishing anything more on religion, a mandate he honored until the king's death in 1797. Kant died February 12, 1804.

Impact on science and religion discussion

Kant's impact on the subject of natural science and religion is best understood in his relation to the Scottish thinker David Hume (17111776), whom Kant claimed awakened him from his dogmatic slumber. Exactly when this was to have occurred is unclear; however, among other things Hume represented for Kant the possibility that the use of reason in fact undermined the essential truths of religion, morality, and common sense. Kant faced squarely Hume's skepticism about causality and other conclusions of common sense that haunted the thinkers of the late eighteenth century. The fear was that if Hume's reasoning was correct about these matters, then how was one to retain one's belief in God? As Kant's contemporary Friedrich Jacobi (17431819) put it, "Nothing frightens man so much, nothing darkens his mind to such a degree as when God disappears from nature when purpose, wisdom, and goodness no longer seem to reign in nature, but only a blind necessity of dumb chance."

In Dialogues Concerning Natural Religion (1779) Hume exposed the inadequacy where the relationship of God to nature was concerned of both classical metaphysical rationalism, in which one reasoned from principles accepted apart from or before experience (a priori), and empiricism, where reasoning was undertaken only after one experienced the world (a posteriori). In the Critique of Pure Reason, Kant attempted to forge a new path between both rationalism and empiricism by introducing what he called in the preface to the second edition a "Copernican" viewpoint in philosophy. The astronomer Nicolaus Copernicus (14831543) had shown that the way to think about the relationship of the earth and the sun was to reverse their traditional roles. Kant demanded that to understand the relationship of the world of experience and the mind one must also reverse the way in which roles were traditionally assigned. It is not that the mind is shaped by experience of the world (empiricism); rather, the world of experience is shaped by "categories" associated with the mind's operation. But in shaping our experience of the world the categories themselves prescribe only the structure for objects of possible experience (not the content of actual experience, as in metaphysical rationalism). Human minds dictate in advance, for example, that experience can only be apprehended in accordance with causal relationships between events, but they cannot determine prior to a person's experiencing the world which specific causal relationships actually obtain. Without content supplied by sense experience, the mind, even equipped as it is by its categories, would still be blind. But without the ordering impact of the categories, experience would be chaos. This is why Kant said at the beginning of the introduction to the Critique that "although all our knowledge begins with experience, it does not follow that it all arises out of experience."

This middle way contained important implications for the understanding of scientific knowledge. If the mind contributes in a formative way to the manner in which people experience the world, then they can no longer claim that the world they experience is necessarily the world that exists apart from the mind. Regularities in one's experience of the world, even those so repetitious as to earn the label of scientific laws, cannot be known as regularities in nature that one discovers; rather, they bear the touch of one's mind. People are, as Kant says in his Prolegomena to Every Future Metaphysics, "lawgivers of reason." Scientific knowledge, then, refers to the world of experience, the world of phenomena apprehended with the senses, not to a reality lying behind human experience. Gone is the possibility of conceiving truth as the correspondence of one's ideas to the way things are, a common conception of many scientists. One cannot be sure of the way things are, so there is no possibility of checking that against one's ideas.

If Kant's critique of reason introduced a radical limitation of what could be known, he was adamant that there was a realm that lay beyond cognition. "I have therefore found it necessary to deny knowledge in order to make room for faith, " he wrote in the preface to the second edition of the Critique. The object of faith, however, could not by definition be articulated or expressed in terms of knowledge. Religion for Kant did not and could not have to do with cognitive propositions about nature. In his 1793 book, Religion within the Boundaries of Reason Alone, he made clear that he accepted Hume's negative conclusions about the so-called argument from design, according to which one reasoned from evidence of design in the world to the existence of a designer. Religion did not commence with nor have to do with one's knowledge of the world. Religion had to do with the purity of one's heart. To be religious is to view one's duties as if they are divine commands. It should be noted that Kant's religious stance was purely intellectual. In spite of the fact that his philosophy made room for the possibility of eternal life, it was clear to those close to him that he scoffed at prayer and other religious practices and that he had no faith in a personal God.

Kant's position, then, radically separated science from religion, as if the two subjects contained no common ground. It took some time for this position to gain a hearing since in the Romantic period, which dominated in the first decades of the nineteenth century, there was great dissatisfaction with Kant's severe restriction of reason's scope to the realm of phenomena. Even one of the earliest neo-Kantian thinkers from this era, Jakob Fries (17731843), added Ahndung (aesthetic sense) to knowledge and faith as a third possible way in which people may relate to that which exists outside of them. Fries believed that through aesthetic sense people could intimate the infinite that was present in the finite.

It was not until the neo-Kantian revival of the late nineteenth century that Kant's radical separation of science from religion emerged in earnest. In the works of the Marburg theologian Wilhelm Herrmann (18461922), composed during the heyday of debates about biological evolution, one recognizes the attempt to cede to natural science the freedom to investigate natural phenomena without restriction while at the same time stressing religion's right to address questions of value and right. If religion must surrender nature to natural science, natural science, in turn, must along with religion renounce any claim to have arrived at metaphysical reality. Religion becomes morality while science becomes Naturbeherrschung, mastery of the world.

In the twentieth century the separation of natural science and religion continued to mark much of German theology, especially the works of well-known existential theologians who wrote in the decades following World War I. Most recently something of a Kantian position on the relationship between science and religion has been advocated by the noted American paleontologist Stephen Jay Gould (19412000) who, without ever naming Kant, introduced the notion of non-overlapping magisteria (NOMA) as a means of dealing with the realities of science, which is concerned with the factual construction of nature, and religion, which concerns itself with moral issues about the value and meaning of life. Gould acknowledge more than classical neo-Kantians, however, that while magisteria do not overlap, they are everywhere interlaced in a complex manner that often makes it extremely challenging to keep the two separate. Critics of the Kantian position maintain that in practice it is impossible to retain a rigid separation of science and religion.

See also Metaphysics; Morality; Natural Theology


beiser, frederick. the fate of reason: german philosophy from kant to fichte. cambridge, mass.: harvard university press 1987.

fries, jakob. knowledge, belief, and aesthetic sense (1805), trans. kent richter, ed. frederick gregory. cologne, germany: dinter verlag, 1989.

gould, stephen jay. rocks of ages: science and religion in the fullness of life. new york: ballantine, 1999.

gregory, frederick. nature lost? natural science and the german theological traditions of the nineteenth century. cambridge, mass.: harvard university press, 1992.

kant, immanuel. cambridge edition of the works of immanuel kant, eds. paul guyer et al. cambridge, uk: cambridge university press, 1992-2001.

kuehn, manfred. kant: a biography. cambridge, uk: cambridge university press, 2001.

frederick gregory

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Kant, Immanuel

Kant, Immanuel



Immanuel Kant (1724–1804) was born in Königsberg (then in East Prussia) and spent his entire life there. He studied at the University of Königsberg and taught there from 1755 until a few years before his death.

Kant’s philosophy lies between empiricism and rationalism. He took from Hume the idea that man is “nothing but a bundle or collection of perceptions which succeed each other with inconceivable rapidity” (Hume 1739–1779, p. 320 in 1826 edition), and from Spinoza the concept that ideas are independent of experience. Yet he could accept neither a pure rationalism nor a pure empiricism; his primary work, theCritique of Pure Reason, begins as follows: “There can be no doubt that all our knowledge begins with experience . . . but it does not follow that it all arises out of experience” ([1781] 1950, p. 41). In this and another major work, Prolegomena to Any Future Metaphysics (1783), he was concerned to find the “valid source” of human knowledge, the way of establishing truth.

Kant’s particular concern was to determine whether what he called synthetic a priori judgments are possible, that is to say, whether it is possible to establish necessary and universal connections among objects. Convinced that mathematics provides such synthetic a priori propositions, he sought to prove that it is possible in like manner to obtain knowledge of the laws of nature.

Newton’s construction of scientific and mathematical theories suggested to Kant the process by which such knowledge might be acquired: “Accidental observations, made in obedience to no previously thought-out plan, can never be made to yield a necessary law, which alone reason is concerned to discover. Reason . . . must approach nature in order to be taught by it. It must not, however, do so in the character of a pupil who listens to every-thing that the teacher chooses to say, but of an appointed judge who compels the witnesses to answer questions which he himself has formulated” ([1781] 1950, p. 20 in Preface to 1787 edition).

Man, according to Kant, approaches experience in terms of basicAnschauungen (kinds of intuition) that are themselves not derived from experience and are not subject to empirical proof; these intuitions are space, time, and causation. Together with four categories (quantity, quality, relation, and modality), these intuitions are the basis of all understanding. Knowledge is merely an application of these categories, or a priori concepts, to sense perceptions, which are intuitively structured in time and space. Human knowledge is limited to these spatial and temporal phenomena; it does not extend to what is behind phenomena, that is, to the noumena, or things-in-themselves.

Influence on psychology. Much controversy in psychology developed as a result of Kant’s distinction between the self as a thing-in-itself, or noumenon, and the self as a phenomenon. Since the first self is the transcendental unity of self-consciousness or apperception, it is inaccessible to inquiry except by introspection; its sole expression is moral judgment. According to Kant, only the phenomenal self can be the subject of empirical studies, and so it becomes part of anthropology (“Anthropologie in pragmatischer Hinsicht” 1798). This empirical or pragmatic psychology deals with what an observer can know about mental processes. Kant’s dichotomy between what an individual may know of his own mind (noumenon) and what others may know of him (phenomenon) gave rise to the controversy between the introspectionist and the behaviorist approaches to psychology.

For the introspectionists, awareness of oneself, Bewusstsein or consciousness, became the core concept and introspection the chief method. Their subject of study was inner experience, and introspection provided the only means of access to the data. The behaviorists rejected this method, relying exclusively on observation of the overt behavior of the phenomenal self.

While Kant’s “anthropology” (i.e., psychology) does not contain many new ideas, his critique of the concept of soul was a significant departure both from the Judaeo-Christian tradition and from Pla-tonic philosophy. “The concept,” he wrote, “is there-fore quite void as regards all hoped-for insight into the cause of appearances and cannot at all serve as a principle of explanation of that which inner or outer experience supplies” ([1783] 1951, p. 79).

Social theory Kant’s social theory was based on the concept of progress, the source of progress being the inner conflict between man’s sociability and his selfishness. Kant called this antagonism the “unsocial sociability.” Man, according to Kant, “has an inclination to socialize himself by associating with others” but he is also driven by anti-social forces. Kant’s conception of the positive dynamic consequences of man’s conflict are well expressed in this passage: “Man wishes concord; but Nature knows better what is good for his species, and she will have discord… The natural impulses that urge man in this direction, the sources of that unsociableness and general antagonism from which so many evils arise, do yet at the same time impel him to new exertion of his powers, and consequently, to further development of his natural capacities” ([1784–1795 1891, pp. 11–12).

The social order that Kant recommended, based as it was on this analysis of man’s nature, would permit a maximum of individual freedom and com-petition, yet would have enough power to restrain this freedom whenever it threatened to produce oppression or anarchy. He proposed a similar system for international affairs; each separate state should be free to run its own affairs, but a supra-national federation of sovereign states would have enough power to regulate international relations and prevent war.

Kant believed not only in political progress—the history of the human race could be viewed as a development toward a perfect political constitution —but also in moral progress. The stages in man’s moral development are anomy, heteronomy, and autonomy. In the natural, primitive, anomic state, impulses were naive, innocent, and uncontrolled. Civilization began when man broke with the natural state and accepted externally imposed moral law; this is the stage of heteronomy. Ultimately, there will be moral autonomy, a state of absolute freedom, in which the individual will obey only a self-imposed law, the “moral imperative.”

Benjamin B. Wolman

[For the historical context of Kant’s work, see the biographies ofHumeand Spinoza. For discussion of the subsequent development of Kant’s ideas, seeGestalt Theory; Phenomenology; Psychology, article onEXISTENTIAL PSYCHOLOGY; and the biographies OfDurkheim; Hegel; Hering; Koffka; KÖhler; kÜlpe; Lotze; MÜller. Georg Elias; Stumpf; Weber, Max; Wertheimer; Wundt.]


(1781) 1950 Immanuel Kant’s Critique of Pure Reason. Translated by N. Kemp Smith. New York: Humanities. → First published in German.

(1783) 1951 Prolegomena to Any Future Metaphysics. New York: Liberal Arts. → First published in German.

(1784–1795) 1891 Kant’sPrinciples of Politics, Including His Essay “On Perpetual Peace.” Edited and translated by W. Hastie. Edinburgh: Clark.→ First published in German.

(1798) 1907 Anthropologie in pragmatischer Hinsicht. Volume 7, pages 117–333 in Kant’s gesammelte Schriften. Berlin: Reimer.

Kant’s gesammelte Schriften. 22 vols. Berlin: Reimer, 1900–1942.


Brett, George S. (1912–1921) 1962 Brett’s History of Psychology. Edited and abridged by R. S. Peters. London: Allen & Unwin; New York: Macmillan.

Cassirer, Ernst 1918 Kants Leben und Lehre. Berlin: Cassirer.

Hume, David (1739–1779) 1964 The Philosophical Works. 4 vols. Edited by Thomas Hill Green and Thomas Hodge Grose. Aalen (Germany): Scientia.

Paton, Herbert J. (1936) 1951 Kant’s Metaphysic of Experience: A Commentary on the First Half of the Kritik der reinen Vernunft. 2 vols. London: Allen & Unwin.

Spinoza, Benedict (1677) 1950 Ethics. Translated by A. Boyle. London: Dent; New York: Dutton.

Weldon, Thomas Dewar (1945) 1958 Kant’s Critique of Pure Reason. 2d ed. Oxford: Clarendon. → First published asIntroduction to Kant’s Critique of Pure Reason.

Wolman, Benjamin B. (editor) Historical Roots of Contemporary Psychology. New York: Harper. → Contains an essay by Wolman on “Immanuel Kant and His Impact on Psychology.” Scheduled for publication in 1968.

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Kant, Immanuel

Kant, Immanuel 1724-1804




Immanuel Kant was born in 1724 in Konigsberg, Prussia (now Kalingrad, Russia). He contributed to metaphysics, epistemology, ethics, and political philosophy. He lived most of his life in Konigsberg, where he died in 1804. He lived long enough to see the early stages of the French Revolution, which he initially welcomed because of its emphasis on both liberty and equality.

Kants philosophy emphasized the reconciliation of disparate themes and theories. In human nature he tried to reconcile the demands of heteronomy and autonomy. The latter has two distinct meanings: one ethical, the second metaphysical. In epistemology he tried to reconcile the competing claims of the rationalistswho emphasized a priori knowledge, primarily mathematicswith those of the empiricists, who claimed that all knowledge is based on experience. David Humes skeptical development of empiricist philosophy, Kant said, interrupted my dogmatic slumber (Kant [1783] 1953, p. 9). Humean skepticism threatened both traditional theism and the recently triumphant Newtonian science.


Kant wanted to defend religion from skeptical arguments and Newtonian science from a similar type of skepticism. He also defended a libertarian theory of human nature from the new determinism that many saw as implicit in Newtonian physics. This is the problem of heteronomy and autonomy. The former is the view that even human behavior is controlled by the same laws as the rest of the universe, implying that free will is an illusion. The latter is the view that not all human actions are dependent on (or deducible from) the laws of nature.

Kants theory of knowledge was based on a complex theory of categories of the mind that we have a priori (prior to, and independently of, experience) and that we apply to experience. Without it we could not have any coherent experience. It constitutes a third way of knowledge between a priori mathematical and logical concepts and those based on experience. It is synthetic a priori knowledge. Just as Copernicus reversed the roles of the sun and earth, so Kant reversed the role of thought and experience: We impose our mental categories on the world, not vice versa.

Kant argued that these concepts applied only to the world of experience and could not apply to metaphysical problems such as God, freedom, and immortality. He produced a complex critique of the three traditional theistic proofs (ontological, teleological, and cosmological) but also argued that reason could not disprove Gods existence, and then offered pragmatic proofs for such a belief. Kants Religion within the Limits of Reason Alone ([1787] 1960) was an attempt to replace religion based on revelation or fideism.


Kants moral philosophy was based on an ethical interpretation of autonomy culminating in his categorical imperative(s) and his proto-liberal political philosophy of freedom. The categorical imperative has two versions: I ought never to act except in such a way that I can also will that my maxim should become a universal law ([1797] 1964, p. 70) and the somewhat clearer, act in such a way that you always treat the person of any other, never simply as a means but always as an end ([1797] 1964, p. 96). The best interpretation of this is: Dont use people as if they were tools or machines; they are persons with independent wills and desires of their own. Because Kant assumed that people have conflicting wills and desires, he asserted that legislators must pass laws that protect everyone equally. Kantian equality is purely formal, meaning that laws must protect everyone equally, but he permitted massive material inequality, based on differences in everyones talent, industry, and good fortune (Two Essays on Right [1797] in Phelps 1973). Kant denied that there could be a principle of welfare or happiness, inferring from this that neither morality nor legislation could be based on experience

Kant distinguished between perfect and imperfect duties. The former are based on the putative rights of others; the latter are not. Therefore, although animals do not have rights, we should not be cruel to them. Charity to the poor is another imperfect duty.

Despite the cosmopolitan character of his categorical imperative and political philosophy, Kant seemed to absorb from Hume an uncritical racism, especially concerning Africans. There are two ways in which one might defend either Kant or Hume. One would be the historicist argument, that we cannot judge people from different times and places by our contemporary standards. The other is to downplay the significance of these views in either philosopher in their overall philosophy. The latter is the more promising route because the eighteenth century was allegedly the age of Reason and Enlightenment. It also was the age in which slavery was first attacked on a widespread basis, leading to its eventual abolition in most of the world. Jeremy Bentham (17481832) argued for decent treatment for blacks, for animals, and (albeit secretly) for homosexuals, on the grounds that the key issue was not Can they reason? but Can they suffer? In addition, racism seems to conflict logically with Kants cosmopolitanism.

Kants greatest influence on the twentieth century may have involved his proposals for perpetual peace via a League of Nations. He also had great faith in republican governments to promote such peace better than monarchies would. In 1784 he wrote What Is Enlightenment? The basic idea was a willingness to dare to think for ourselves. His idea of autonomy, however, should not be confused with a do your own thing mentality: Instead, it meant that the laws we impose on ourselves are based on logically impeccable arguments.

SEE ALSO Autonomy; Bentham, Jeremy; Enlightenment; Epistemology; Ethics; Hermeneutics; Hume, David; League of Nations; Philosophy; Racism; Religion; Slavery


Kant, Immanuel. [1781] 1902. Critique of Pure Reason. New York: Collier.

Kant, Immanuel. [1783] 1953. Prolegomena to Any Future Metaphysics. Manchester, U.K.: Manchester University Press.

Kant, Immanuel. [1785; 1784] 1959. Groundwork of the Metaphysics of Morals, and an Answer to the Question: What Is Enlightenment? Indianapolis, IN: Bobbs-Merrill

Kant, Immanuel. [1787] 1960. Religion within the Limits of Reason Alone. Trans. with intro. and notes Theodore M. Greene and Hoyt H. Hudson. New York: Harper and Row.

Kant, Immanuel. [1788] 1956. Critique of Practical Reason. Indianapolis, IN: Bobbs-Merrill.

Kant, Immanuel. [1790] 1964. Critique of Judgement. New York: Hafner.

Kant, Immanuel. [1797] 1964. Groundwork of the Metaphysics of Morals. New York: Harper and Row.

Kant, Immanuel. 1963. On History, ed. with intro Lewis White Beck; trans. Lewis White Beck, Robert E. Anchor, and Emil L. Fackenheim. Indianapolis, IN: Bobbs-Merrill.

Phelps, Edmund, ed. 1973. Economic Justice: Selected Readings. Middlesex, U.K.: Penguin.

Calvin Hayes

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Kant, Immanuel (1724–1804)

KANT, IMMANUEL (17241804)

KANT, IMMANUEL (17241804), German philosopher. Immanuel Kant was born 24 April 1724 in Königsberg (now Kaliningrad) in East Prussia. He attended a Pietist school and the University of Königsberg and in 1755, after six years as a private tutor, obtained a position at his university. Promoted to professor there in 1770, he taught and served in administrative posts until 1798 and died 12 February 1804.


Kant's predecessors had treated knowledge as beginning from data about the world that the mind passively receives from the senses or through immediate insight into eternal truths or ideas. Kant, by contrast, made the activity of the mind central both to the world as we live in it and to our knowledge of it.

Kant built his systematic theoretical philosophy around the idea that the world as we experience it does not exist independently of us. Our own minds, he argued, are responsible for its form and structure. This idea constituted his "Copernican revolution." Before Copernicus, astronomical data were explained by assuming that the sun revolves around the earth. Reversing this, Copernicus explained the data by taking the earth to revolve around the sun. Kant explained experience by denying that our knowledge conforms to objects, instead holding that objects in experience conform to our knowledgeto the way our mind necessarily works.

In moral philosophy Kant proposed an equally revolutionary idea. In morality, he held, we are not required to obey laws imposed by God or eternal moral principles or Platonic forms; instead we must understand morality as resting on a law that springs from our own practical rationality. We are "autonomous" because we legislate the moral law we are to obey. The form of the moral world results from the mind's activity.

These views were designed to protect scientific knowledge from skeptical attacks such as that of David Hume (17111776) and also to show how morality and responsibility could be preserved in a Newtonian deterministic universe. Kant's theoretical philosophy laid the foundations for the whole enterprise.


In the Kritik der reinen Vernunft (1781; Critique of pure reason) Kant criticized his predecessors for not seeing that there is a deep difference between perceptual experiences and abstract concepts. The mind accepts the "percepts" that things outside it cause in it, but the mind itself imposes a framework of both time and space even on such given data. Concepts are rules by which the mind organizes percepts, and they show the mind's activity. The mind of any rational agent is equipped with several basic "categories," which are fundamental ways of organizing the data accepted through the senses. Nothing can be part of our experience, therefore, unless it is temporal and spatial and is organized by categories like those of continuing physical object and cause and effect. Percepts and concepts together yield the world as we live in it. The mind's structure explains how we can attain necessary truth in our knowledge of this world.

Kant allows that we can think of a thing as it is in itself (Ding an sich) outside experiencea noumenonbut insists that we can know only things as they are for usas phenomena. Because percepts as well as concepts are necessary for knowledge, we cannot know anything at all about what goes beyond possible experience. Hence we cannot have answers, either positive or negative, to what were then the main questions of religion and metaphysics: Does God exist? Are we immortal? Are we free?


In the Grundlegung zur Metaphysik der Sitten (1785; Groundwork of the metaphysics of morals) and the Kritik der praktischen Vernunft (1788; Critique of practical reason) Kant claimed that, in the practical realm, our desires are the counterpart to given sensory data in theoretical knowledge. But we are not causally determined to accept desires as giving us reasons to act. We are free because our will enables us to affirm or reject the claim of any desire to be a reason. Only what the will accepts is a reason to act. And the will, which Kant defines as practical reason, imposes its own forms prior to allowing a desire to count as a reason.

The forms the will imposes on desires include the master form, which is the moral law. As it applies to us, the moral law is an imperative or directive that cannot reasonably be flouted: it is the "categorical imperative." It tells us to act only on plans we could rationally allow everyone to act on. Hence morality, under the categorical imperative, would create a harmonious moral world out of desires that would naturally all too often lead us into conflict.


Because he denied that we could know anything that goes beyond experience, Kant seemed to his contemporaries to have eliminated all hope for a rational religion. But he said that he had destroyed knowledge to make room for faith. He tried to justify a religion safe from scientific criticism by arguing that the categorical imperative gives us practical or moral reason to believe in the essential religious tenets: God, freedom, and immortality. If few philosophers have been convinced by his moral arguments for God and immortality, many think that his account of freedom still has great appeal.


Kant aimed to limit naturalismthe view that a single system of causation explains all human activity as well as all other events. To do so, he made philosophy the master discipline that sets boundaries to the cognitive claims of all other thinking. Science is the judge of beliefs about experience, but it can say nothing about claims concerning morality or religion, or (as Kant also argued) about aesthetic taste. His remarkable theory that the mind helps construct the world in which we live opened the way for the radical idealisms of Friedrich Wilhelm Joseph von Schelling (17751854), Johann Gottlieb Fichte (17621814), and Georg Wilhelm Friedrich Hegel (17701831). Kant's assertion of "the primacy of practical reason"that practical reason can answer questions that theoretical reason cannotwas suggestive for the development of pragmatism. His moral philosophy has been and still is both widely used and hotly contested. Kant's work has had an influence on Western thought unsurpassed by that of any other modern philosopher.

See also Hume, David ; Moral Philosophy and Ethics ; Natural Law.


Primary Sources

The Cambridge Edition of the Works of Immanuel Kant, edited by Paul Guyer and Allen W. Wood, Cambridge, U.K., 1992. Contains the best translations of Kant's works, from the early "pre-critical" writings through the Opus Postumum, and including extensive selections from student lecture notes.

Kant, Immanuel. Gesammelte Schriften. Vols. 127. Berlin, 1969.

Secondary Sources

Guyer, Paul, ed. Cambridge Companion to Kant. Cambridge, U.K., 1992. Contains articles covering most aspects of Kant's philosophy and a good bibliography.

Kuehn, Manfred. Kant: A Biography. Cambridge, U.K., 2001. Excellent scholarly bibliography.

J. B. Schneewind

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Kant, Immanuel

Immanuel Kant (Ĭmän´ōōĕl känt), 1724–1804, German metaphysician, one of the greatest figures in philosophy, b. Königsberg (now Kaliningrad, Russia).

Early Life and Works

Kant was educated in his native city, tutored in several families, and after 1755 lectured at the Univ. of Königsberg in philosophy and various sciences. He became professor of logic and metaphysics in 1770 and achieved wide renown through his writings and teachings. His early work, reflecting his studies of Christian Wolff and G. W. Leibniz, was followed by a period of great development culminating in the Kritik der reinen Vernunft (1781, tr. Critique of Pure Reason). This work inaugurated his so-called critical period—the period of his major writings. The more important among these writings were Prolegomena zu einer jeden künftigen Metaphysik (1783, tr. Prolegomena to Any Future Metaphysics), Grundlegung zur Metaphysik der Sitten (1785, tr. Foundations of the Metaphysics of Morals), Kritik der praktischen Vernunft (1788, tr. Critique of Practical Reason), and Kritik der Urteilskraft (1790, tr. Critique of Judgment). His Religion innerhalb der Grenzen der blossen Vernunft (1793, tr. Religion within the Limits of Reason Alone) provoked a government order to desist from further publications on religion.


According to Kant, his reading of David Hume awakened him from his dogmatic slumber and set him on the road to becoming the "critical philosopher," whose position can be seen as a synthesis of the Leibniz-Wolffian rationalism and the Humean skepticism. Kant termed his basic insight into the nature of knowledge "the Copernican revolution in philosophy."

Instead of assuming that our ideas, to be true, must conform to an external reality independent of our knowing, Kant proposed that objective reality is known only insofar as it conforms to the essential structure of the knowing mind. He maintained that objects of experience—phenomena—may be known, but that things lying beyond the realm of possible experience—noumena, or things-in-themselves—are unknowable, although their existence is a necessary presupposition. Phenomena that can be perceived in the pure forms of sensibility, space, and time must, if they are to be understood, possess the characteristics that constitute our categories of understanding. Those categories, which include causality and substance, are the source of the structure of phenomenal experience.

The scientist, therefore, may be sure only that the natural events observed are knowable in terms of the categories. Our field of knowledge, thus emancipated from Humean skepticism, is nevertheless limited to the world of phenomena. All theoretical attempts to know things-in-themselves are bound to fail. This inevitable failure is the theme of the portion of the Critique of Pure Reason entitled the "Transcendental Dialectic." Here Kant shows that the three great problems of metaphysics—God, freedom, and immortality—are insoluble by speculative thought. Their existence can be neither affirmed nor denied on theoretical grounds, nor can they be scientifically demonstrated, but Kant shows the necessity of a belief in their existence in his moral philosophy.

Kant's ethics centers in his categorical imperative (or moral law)— "Act as if the maxim from which you act were to become through your will a universal law." This law has its source in the autonomy of a rational being, and it is the formula for an absolutely good will. However, since we are all members of two worlds, the sensible and the intelligible, we do not infallibly act in accordance with this law but, on the contrary, almost always act according to inclination. Thus what is objectively necessary, i.e., to will in conformity to the law, is subjectively contingent; and for this reason the moral law confronts us as an "ought."

In the Critique of Practical Reason Kant went on to state that morality requires the belief in the existence of God, freedom, and immortality, because without their existence there can be no morality. In the Critique of Judgment Kant applied his critical method to aesthetic and teleological judgments. The chief purpose of this work was to find a bridge between the sensible and the intelligible worlds, which are sharply distinguished in his theoretical and practical philosophy. This bridge is found in the concepts of beauty and purposiveness that suggest at least the possibility of an ultimate union of the two realms.

The Impact of Kantian Philosophy

The impact of Kant's work has been incalculable. In addition to being the impetus to the development of German idealism by J. G. Fichte, F. W. Schelling, and G. W. F. Hegel, Kant's philosophy has influenced almost every area of thought. Among the major outgrowths of Kant's work was the Neo-Kantianism of the late 19th cent. This movement had many branches in Germany, France, and Italy; the two chief ones were the Marburg school, founded by Hermann Cohen and including Ernst Cassirer, and the Heidelberg school, led by Wilhelm Windelband and Heinrich Rickert.

The Marburg school was primarily concerned with the application of Kantian insights to the understanding of the physical sciences, and the Heidelberg school with the application of Kant to the historical and cultural sciences. Closely connected with the latter group was the social philosopher Wilhelm Dilthey. Kant influenced English thought through the philosophy of Sir William Hamilton and T. H. Green, and some Kantian ideas are found in the pragmatism of William James and John Dewey. In theology, Kant's influence can be seen in the writings of Friedrich Schleiermacher and Albrecht Ritschl; his ideas in biology were developed by Hans Driesch and in Gestalt psychology by Wolfgang Köhler. All of Kant's important works have been translated into English.


See H. W. Cassirer, A Commentary on Kant's Critique of Judgment (1938, repr. 1970) and Kant's First Critique (1954); L. W. Beck, Studies in the Philosophy of Kant (1965) and (ed.) Kant Studies Today (1969); H. Arendt, Lectures on Kant's Philosophy (1989); J. K. Uleman, An Introduction to Kant's Moral Philosophy (2010).

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Kant, Immanuel

Immanuel Kant

Born: April 22, 1724
Königsberg, East Prussia
(now Kaliningrad, Russia)
Died: February 12, 1804
Königsberg, East Prussia

German philosopher

The major works of the German philosopher Immanuel Kant offer an analysis of theoretical and moral reason and the ability of human judgment. He had a great influence on the intellectual movements of the nineteenth and twentieth centuries.

Childhood and education

The fourth of nine children of Johann Georg and Anna Regina Kant, Immanuel Kant was born in the town of Königsberg, East Prussia, on April 22, 1724. Johann Kant was a harness maker, and the large family lived a humble life. The family belonged to a Protestant religious group of Pietists (a German religious movement whose members strongly believed in religious experience and biblical study), and a concern for religion touched every aspect of their lives. Although Kant became critical of formal religion, he continued to admire the "praiseworthy conduct" of Pietists. Kant's elementary education was at Saint George's Hospital School and then at the Collegium Fredericianum, a Pietist school, where he remained from 1732 until 1740. Here he gained a deep appreciation for the classics of Latin literature, especially the poet Lucretius.

In 1740 Kant entered the University of Königsberg. He became interested in philosophy, mathematics, and the natural sciences. The death of Kant's father in 1746 left him without income. He became a private tutor for seven years in order to have enough time and money to continue his education. During this period Kant published several papers dealing with scientific questions. The most important was the "General Natural History and Theory of the Heavens" in 1755. In this work Kant concluded the origin of the solar system was a result of the gravitational (having to do with the force exerted between bodies of matter) connection of atoms (the smallest pieces of matter). In the same year Kant presented a Latin treatise, "On Fire," to qualify for the doctoral degree.

Kant spent the next fifteen years (17551770) as a lecturer. In order to live he lectured between twenty-six and twenty-eight hours a week. Despite this enormous teaching burden, Kant continued to publish papers on various topics. He finally achieved a professorship at Königsberg in 1770.

Critique of Pure Reason

At the age of fifty-seven Kant published the first edition of the Critique of Pure Reason (1781; 2d ed. 1787). This enormous work is one of the most important and difficult books in Western thought. The aim of the critique is to explain how experience and reason interact in thought and understanding. The Critique of Pure Reason is a methodology (a collection of methods and rules) of how "understanding and reason [the power of understanding] can know apart from experience." This revolutionary proposal means that the mind organizes our experiences into the way the world appears and the way that we think about the world. Any experience is placed into one of these categories so that it can be understood. Kant also wrote that the mind can have knowledge of things that have or have not been experienced, but these are only possibilities. Kant does not say that the mind creates objectsonly the conditions under which objects are noticed and understood. We can never know noumenal reality (theoretical objects or ideas that are understood by thought alone) with any certainty.

Kant suggests that the theories of God, freedom, and immorality (something that goes against ideas or right and wrong) are not proved or disproved through the use of reason, nor can the use of scientific methods prove or disprove their existence. The idea of them is beyond the realm of human experience. Kant expressed that faith in God, freedom, and immorality are rational beliefs because their existence makes an orderly and moral world a possibility.

Later works

In 1783 Kant restated the main outlines of his first critique in a brief, analytic form in the Prolegomena to Any Future Metaphysics. In 1785 he presented an early view of the practical aspects of reason in Fundamental Principles of the Metaphysic of Morals. In 1788 he published the Critique of Practical Reason.

While theoretical reason is concerned with knowledge, practical reason is concerned with will, or self-determination. There is only one human reason, but after it decides what it can know, it must determine how it shall act. Thus the freedom of the will determines how one shall lead his life. And the basic, reasonable principle of a free morality (a morality that one is free to choose) is some universal and necessary law which follows. This principle is called by Kant the "Categorical Imperative," which states that a man should act in a way that is acceptable and applicable to all people. In questioning the outcome of man's freedom, Kant insists that practical reason assumes the immortality of the soul and the existence of God as the conditions for true freedom.

In 1790 Kant completed his third critique, which attempts to draw these conflicting ideas together. The Critique of Judgment attempts to connect the concepts of nature with the concepts of freedom.

Although Kant continued to write until shortly before his death, the "critical works" are the source of his influence. Only a life of extraordinary self-discipline enabled him to accomplish his task. He was barely five feet tall and extremely thin, and his health was fragile. Toward the end of his life he became increasingly antisocial and bitter over the growing loss of his memory and capacity for work. Kant became totally blind and finally died on February 12, 1804, in Königsberg.

For More Information

Kuehn, Manfred. Kant: A Biography. New York: Cambridge University Press, 2001.

Scruton, Roger. Kant: A Very Short Introduction. Rev. ed. New York: Oxford University Press, 2001.

Sedgwick, Sally, ed. The Reception of Kant's Critical Philosophy: Fichte, Schelling, and Hegel. New York: Cambridge University Press, 2000.

Stuckenberg, J. H. W. The Life of Immanuel Kant. London: Macmillan, 1882. Reprint, Lanham, MD: University Press of America, 1986.

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Kant, Immanuel


Immanuel Kant shook the foundations of Western philosophy in the late eighteenth and early nineteenth centuries. This author and professor did his most important writing between 1781 and 1790 while working at the University of Königsberg, where he spent most of his life. Kant's philosophical model not only swept aside the ideas of the so-called empiricists and rationalists who came before him, it also had a lasting effect outside of philosophy, especially in the areas of ethics and the law. Today, legal scholars still debate his ideas—and their sometimes startling implications—in relation to contemporary issues.

Kant was born into a lower-middle-class family in East Prussia in 1724. A gifted student, he studied in a Latin school from age eight until age sixteen, when he entered the University of Königsberg to take up theology, natural science, and philosophy. The death of his father forced

him to abandon his studies in order to work as a private tutor, and he had to wait several years before returning to complete his education. By that time he was already writing serious books. From what is called Kant's precritical period, these early works are primarily scientific. In recognition of his talents, the university made him a lecturer and eventually a professor. He taught logic and metaphysics.

Twenty years later Kant attacked the reigning schools of thought. In this so-called critical period, he wrote his most famous book, The Critique of Pure Reason (1781). Kant's work examined the relation of experience and perception: he was concerned with how people know what they know, and just as important, the proper uses of the powers of reasoning. He argued that reality can be perceived only to the extent that it complies with the aptitude of the mind that is doing the perceiving. This places one kind of

limitation on what can be known. Kant saw another limitation, too: only phenomena—things that can be experienced—are capable of being understood; everything else is unknown. The human senses, therefore, take supreme precedence in determining what is real.

These theories have implications for conventional morality. Kant viewed God, freedom, and immortality as incomprehensible: they can only be contemplated; their existence can never be proved. Nonetheless, he argued, all three of them are important as the basis for morality. Kant believed that reason is insufficient to justify moral behavior. The justification for behaving morally has to come from people's sense of duty, which he called the categorical imperative.

Kant continued to develop his philosophy in subsequent books including Critique of Judgment (1790) and Religion within the Limits of Reasons Alone (1793). The latter enraged the government, resulting in its censorship and an official order to Kant to write no more books about religion.

"The greatest problem for the human species, the solution of which nature compels him to seek, is that of attaining a civil society which can administer justice universally."
—Immanuel Kant

Philosophers have studied Kant's work for over two centuries, but legal thinkers outside of Europe have only widely treated it in recent years. In the late twentieth century, when many U.S. scholars of law turned to interdisciplinary studies that involved the fields of economics and textual analysis, Kant provided another model for argument. Kant's ideas cover the foundation of law while specifically addressing property, contracts, and criminal punishment. Kant proposed that punishment should be meted out strictly without exception—because of society's duty to seek retribution. "[I]f justice goes," Kant wrote in 1797, "there is no longer any value in men's living on the earth."

further readings

Fletcher, George P. 1987. "Why Kant." Columbia Law Review 87 (April).

Gillroy, John Martin. 2000. Justice & Nature: Kantian Philosophy, Environmental Policy & the Law. Washington, D.C.: Georgetown Univ. Press.

Goodrich, Peter. 2001. "Barron's Complaint: A Response to "Feminism, Aestheticism and the Limits of Law." Feminist Legal Studies 9 (August): 149–70.

Kant, Immanuel. 1991. "Metaphysical First Principles of the Doctrine of Right." In The Metaphysics of Morals. Translated by Mary Gregor. Cambridge; New York: Cambridge Univ. Press.

Tunick, Mark. 1998. Practices and Principles: Approaches to Ethical and Legal Judgment. Princeton, N.J.: Princeton Univ. Press.

Waldron, Jeremy. 1996. "Kant's Legal Positivism." Harvard Law Review 109 (May).

Wright, R. George. 2002. "Treating Persons as Ends in Themselves; the Legal Implications of a Kantian Principle. University of Richmond Law Review 36, (March): 271–326.


Hegel, Georg Wilhelm Friedrich; Jurisprudence.

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Kant, Immanuel

Kant, Immanuel (1724–1804) One of the greatest, if not the greatest, of all modern philosophers, the German Immanuel Kant has had a profound and lasting influence both in philosophy itself, and across the full range of intellectual disciplines, including of course sociology. The core of Kant's critical philosophy is generally taken to be his synthesis of the two rival traditions of empiricism and rationalism which dominated epistemology (or philosophical theory of knowledge) in Kant's time. Kant argued, against the empiricists, that there were true synthetic a priori judgements; that is to say, judgements which were not mere tautologies, yet which were not derived from experience. Kant's great work the Critique of Pure Reason (1781) is devoted to the demonstration of this claim and to the systematic derivation of those synthetic a priori concepts and judgements which were conditions of the possibility of our apprehension of space and time (the ‘forms of intuition’), and our making of objective judgements of experience (the ‘categories’—causality, necessity, possibility, and others). For Kant, however, the categories, whilst not derivable from experience, could be legitimately applied only within the field of possible experience. To use the categories to offer accounts of ‘things-in-themselves’, beyond possible experience, was to fall into irresolvable contradiction. So, whilst rejecting a central doctrine of empiricism, Kant nevertheless shared with the leading empiricists a concern to defend the cognitive status of empirical science against theological and metaphysical claims to knowledge of ‘things-in-themselves’ beyond experience.

Howvever, for Kant, thought about ‘things-in-themselves’ was unavoidable, even if knowledge of them was impossible. This was not least because of the necessity of a rational grounding for objective moral judgement. For an individual to be bound by a moral maxim requires both freedom of will and a unitary personal identity, neither of which is to be found among the contents of experience. Kant's treatment of aesthetics (in the Critique of judgement, 1790) also makes use of ideas (such as ‘the form of purposiveness’) which can have no application in objective judgements of experience. Despite the anti-metaphysical leanings of the central arguments of Kant's Critique of Pure Reason, therefore, there remains a tension between a realm of objectively knowable objects of experience, on the one hand, and unavoidable allusions to an unknowable realm of ‘things-in-themselves’, on the other. This latter realm is especially required in the grounding of moral and aesthetic judgement and the identity of the perceiving, knowing, and acting subject.

The principal non-positivist epistemologies which have been influential in sociology derive from various European traditions of interpretation and resolution of these tensions in Kant's philosophy (most especially neo-Kantianism, phenomenology, and hermeneutics—for all of which see separate entries in this dictionary). Hegel's historical dialectic of self-realization of the ‘Absolute Idea’ arose from the critique of Kant's philosophy and went on to inform both the view of history and the epistemology of Marx and Engels.

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Kant, Immanuel (1724-1804)

Kant, Immanuel (1724-1804)

German philosopher, born on April 22, 1724, who anticipated the modern pictographic conception of apparitions in his analysis of the experiences of Emanuel Swedenborg in Dreams of a Spirit-Seer (1766). He was impressed with Swedenborg's attempts, with some seeming success, to communicate with the deceased brother of the wife of the king of Sweden. In his book, written several years later, Kant explores the possibility of the existence of disembodied spirits and their ability to communicate with humans: "Departed souls and pure spirits can still act upon the soul of man. For the ideas they excite in the soul clothe themselves according to the law of fantasy in allied imagery and create outside the seer the apparition of the objects to which they are appropriate."

Kant did not distinguish between veridical and objective apparitions and after some perfunctory speculation laid the subject aside.

In Dreams of a Spirit-Seer Kant expresses admiration for some of Swedenborg's insights, although he questions the seer's sanity and pokes fun at some of his more extravagant claims. He later acknowledges, albeit grudgingly, an affinity between his philosophy and Swedenborg's: "The system of Swedenborg is unfortunately very similar to my own philosophy. It is not impossible that my rational views may be considered absurd because of that affinity. As to the offensive comparison I declare we must either suppose greater intelligence and truth at the basis of Swedenborg's writings than the first impression excites, or that it is a mere accident when he coincides with my system."

Kant died on February 12, 1804.


Berger, Arthur S., and Joyce Berger. The Encyclopedia of Parapsychology and Psychical Research. New York: Paragon House, 1991.

Broad, C. D. "Immanuel Kant and Psychical Research." Proceedings of the Society for Psychical Research 49 (1950).

Kant, Immanuel. Träume eines Geistersehers erläutert durch die Träume der Metaphysik. 1766. Translated as Dreams of a SpiritSeer. N.p., 1900.

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Kant, Immanuel

Kant, Immanuel (1724–1804). German philosopher. He was born in Königsberg of devoutly Pietist parents, and spent all his life there, becoming Professor of logic and metaphysics at the university in 1770.

He wrote his most important books in his later years, especially the three Critiques. The Critique of Pure Reason (1781) deals with fundamental questions about human knowledge, understanding, and reason, and has been one of the most influential works of modern philosophy. In the later part of the Critique Kant criticizes the ontological, cosmological, and teleological arguments for God's existence. He allows, however, that the ideas of God, the soul, and the world may have what Kant calls a ‘regulative’ role. Thus, although Kant attacked traditional metaphysics and natural theology, he allowed for the possibility of a ‘rational faith’.

Kant's Groundwork of the Metaphysic of Morals (1785) is a significant work on moral philosophy, famous for its discussion of the ‘categorical imperative’, a test whereby we judge our moral principles at the bar of reason, to see if they are indeed universal rules valid for all people.

Kant's last substantial discussion of religious questions was his Religion within the Bounds of Reason Alone (1793), in which he further developed his idea of a ‘pure, rational religion’, rejecting ‘false worship’. He discussed questions concerning divine commands, grace, the nature of Christ's redemption, the atonement, and the Church, stressing the primacy of the rational moral judgement and often criticizing traditional doctrines.

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Kant, Immanuel

Kant, Immanuel (1724–1804) German metaphysical philosopher. He was a teacher and professor of logic and metaphysics at the University of Königsberg. The order and modesty of Kant's life was undisturbed by the notoriety caused by his publications. Kant's philosophy of idealism, outlined in Critique of Pure Reason (1781), sought to discover the nature and boundaries of human knowledge. It was much influenced by Isaac Newton and David Hume. Kant's system of ethics, described in the Critique of Practical Reason (1790), places moral duty above happiness and asserts the existence of an absolute moral law (the “categorical imperative”). His views on aesthetics are embodied in his Critique of Judgment (1790). Kant also produced several essays in support of religious liberalism and the Enlightenment.

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Kant, Immanuel

Kant, Immanuel (1724–1804). German philosopher. His Observations on the Feeling of the Beautiful and Sublime (1764) and Critique of Judgement (1790) laid the foundations of much aesthetic theory, especially in relation to the Beautiful and the Sublime discussed earlier by Edmund Burke in 1756.


Chilvers, Osborne, & Farr (eds.) (1988);
H. O (1970);
Jane Turner (1996)

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