The term rationalism (from the Latin ratio, "reason") has been used to refer to several different outlooks and movements of ideas. By far the most important of these is the philosophical outlook or program that stresses the power of a priori reason to grasp substantial truths about the world and correspondingly tends to regard natural science as a basically a priori enterprise. Although philosophies that fall under this general description have appeared at various times, the spirit of rationalism in this sense is particularly associated with certain philosophers of the seventeenth and early eighteenth centuries, the most important being René Descartes, Benedict de Spinoza, and Gottfried Wilhelm Leibniz. It is rationalism of this type that will be the subject of this entry.
Two other applications of the term should, however, be distinguished.
Rationalism in the Enlightenment
The term rationalism is often loosely used to describe an outlook allegedly characteristic of some eighteenth-century thinkers of the Enlightenment, particularly in France, who held an optimistic view of the power of scientific inquiry and of education to increase the happiness of humankind and to provide the foundations of a free but harmonious social order. In this connection "rationalistic" is often used as a term of criticism, to suggest a naive or superficial view of human nature that overestimates the influence of benevolence and of utilitarian calculation and underestimates both the force of destructive impulses in motivation and the importance of such nonrational factors as tradition and faith in the human economy. Jean d'Alembert, Voltaire, and the Marquis de Condorcet, among others, are often cited in this connection. Although there is some truth in these criticisms, the naïveté of these and other Enlightenment writers has often been grossly exaggerated. Also, insofar as "reason" is contrasted with "feeling" or "sentiment," it is somewhat misleading to describe the Enlightenment writers as rationalistic, for many of them (Denis Diderot, for example) characteristically emphasized the role of sentiment. Reason was praised in contrast with faith, traditional authority, fanaticism, and superstition. It chiefly represented, therefore, an opposition to traditional Christianity.
Here there are two contrasts with the seventeenth-century rationalism of Descartes and others. First, this rationalism is not characteristically antireligious or nonreligious; on the contrary, God in some sense, often in a traditional sense, plays a large role in rationalist systems (although Spinoza's notion of God was extremely unorthodox, and it is notable that the opposition of reason and faith is important in his Tractatus Theologico-Politicus ). Second, the view of science held by such Enlightenment thinkers as Voltaire was different from that of rationalism, being much more empiricist. The central contrast embodied in the term rationalism as applied to the earlier systems is that of reason versus experience, a contrast that is certainly not present in the Enlightenment praise of the "rational." Parallel to this difference, there is a difference between the characteristic seventeenth- and eighteenth-century views on the nature and importance of system; the eighteenth century declared itself against the esprit de système of the seventeenth century, with its elaborate metaphysical systems, and in favor of an esprit systématique, which could be orderly without being speculatively ambitious. (See d'Alembert, Preliminary Discourse to the Encyclopédie and Condillac, Traité des systèmes.)
Rationalism in Theology
The Enlightenment spirit of rational criticism directed against the supposed revealed truth of the Scriptures also had effects within Christianity itself. In this connection the term rationalism is used in a specific theological sense to refer to the doctrines of a school of German theologians that was prominent roughly between 1740 and 1840, and which had great influence on the development of biblical criticism. With their spirit of antisupernaturalism can be associated Immanuel Kant's Die Religion innerhalb der Grenzen der blossen Vernunft (1793), in which rational morality is the basis of religious belief.
However, the best-known use of "rationalism" in a religious connection is an entirely negative one, in which it stands for an antireligious and anticlerical movement of generally utilitarian outlook, laying great weight on historical and scientific arguments against theism. This use of the term, a popular rather than a technical one, seems now to be obsolescent, its place being taken by humanism.
Rationalism versus Empiricism
Rationalism as it will be discussed here is standardly contrasted with empiricism. This contrast (which rests on that contrast between reason and experience which has already been mentioned) is now so basic to the use of the terms that no account can afford to ignore it, and a number of comparisons between views associated with these two outlooks will be made in the course of this entry. It is of course impossible to give a detailed comparison of the two outlooks, and in general comparisons will be introduced incidentally to the account of rationalist ideas. There is, however, one issue, that of innate ideas, which embodies a central disagreement between the two, and regarding which an account merely from the rationalist side would be particularly unilluminating. On this issue the disagreements will be considered in rather greater detail than elsewhere. At the same time, it is hoped that the treatment of this issue will give slightly more insight into the rationalist outlook than can be achieved by what is at other points inevitably a very selective summary of rationalist opinions.
Descartes distinguished three classes of "ideas" (by which he meant merely whatever it is in a man's mind in virtue of which he can be said to be thinking of a given thing): adventitious, factitious, and innate. The first type came to the mind from experience, the second were constructed by the mind's own activity, and the third were created by God together with the mind or soul itself. The last included what were for Descartes the three fundamental ideas of the basic types of substance: God, mind, and matter (or extension). For the most part Descartes argued negatively for the view that these ideas are innate, trying to show that they could not be derived from experience (where this means, fundamentally, sensation).
His argument had two main points. First, the ideas are pure, containing no sensory material; these ideas are not images, reproductions, or copies of sensory experience. Descartes regarded this as fairly obvious in the cases of God and of mind; and he made a particular effort (as in the argument of the wax in Meditations II) to establish the same claim for matter. Second, the fundamental ideas implicitly contain, in different ways, some idea of infinity, and in grasping the idea one thereby grasps the possibility of infinitely many and various modifications to which mind and matter can be subject. In the case of God this argument goes further, for here we grasp an actual infinity of perfections implicit in the idea. The same point, however, holds for all these ideas: The grasp of infinitely many possibilities must transcend what has been given to us in experience, since experience could have given us at best only a limited set of such conceptions, corresponding to what had actually been experienced.
Even if both points of the argument are granted as showing that these ideas are not totally derived from experience, it might be doubted whether they are enough to show that the ideas are innate. For might they not be grasped in some nonempirical manner at a later stage of life—for example, when (or if) someone comes to think in these very general terms? In Descartes's philosophy there is at least an implicit answer to this objection. Descartes thought that the pure ideas of mind and matter are used in the comprehension of experience even before they become conscious in reflection. It is by reference to these ideas that one forms the ordinary unreflective conceptions of oneself as having a series of thoughts or of a material object as enduring, occupying space, and having various characteristics, even though, before reflection, one's conceptions of these things will be confused. Thus, the operation of the pure idea is implicit in ordinary prereflective experience, and such experience begins to be acquired from the moment of birth; therefore, there is ground for calling the pure ideas innate.
In the case of God the argument is slightly different, since it is less clear that this idea is "put to use" in any prereflective way. Here Descartes may have meant to claim merely that it would be natural to the power and economy of God's operations that he should implant the idea of himself in the soul at its creation, "the mark," as Descartes put it, "of the workman on his work." There is indeed a difficulty in seeing how, for Descartes, there could be an idea in the mind of which the mind is not fully conscious (as this account implies), since for Descartes "mind" and "consciousness" were virtually equivalent. And this difficulty also arises for the ideas of mind and matter, since Descartes explicitly denied (presumably there was no alternative) that the infant or young person is fully conscious of his innate ideas; they are latent and emerge only later—in the process of learning language, for instance. Nevertheless, Descartes's claims for the operation of fundamental ideas in prereflective consciousness, although not quite consistent with his metaphysics of the mind, became an important element in later theories of innate ideas, especially in the debate with empiricism.
Descartes appealed only to innate ideas, or concepts, the materials of judgments and beliefs. He did not invoke innate principles, or propositions, his view apparently being that granted innate ideas, we have only to grant in addition a certain power of the mind to elicit features implicit in these ideas in order to explain how necessary knowledge could be derived from innate ideas (as he supposed it could).
Leibniz, however, who continued the Cartesian insistence on innate ideas, added a requirement for innate principles. His argument was of the same general type as that ascribed to Descartes with respect to the ideas of mind and matter: If there were no innate and unlearned propositions, we could learn no propositions at all—at least not by way of logical deduction. For, he argued, confronted with any valid inference of the form "P, so Q," we could not see that Q followed from P except by having already grasped the necessary truth of the proposition "if P then Q." Thus, in order to follow any inference and to learn anything by deduction, first premises are required that must themselves be unlearned.
An objection to this argument can be seen from the famous difficulty raised by Charles L. Dodgson (Lewis Carroll) that if there is necessarily a difficulty in seeing the validity of the original inference as it stands, the same difficulty will recur with the inference obtained by the addition of the "innate" major premise; to grasp the validity of this inference, another major premise would seem to be required, and so on, thus starting a vicious regress. Dodgson's point makes it clear that no multiplication of premises can be adequate to extricate the validity of an inference; what is needed is something of a different category, a rule. At this point a characteristic empiricist rejoinder to Leibniz's puzzle is to claim that the rules of inference are not unlearned but are learned in the course of learning a language (they are the rules implicit in the correct use of "if," "then," "not," and so on). This illustrates the natural and perhaps inevitable tendency of empiricism, in contrast with rationalism, to turn to a linguistic account of logical necessity. (Such an account, however, even if adequate in itself, may not dispose of the issues as thoroughly as empiricism has tended to believe; the question remains of what is involved in learning a language.)
Leibniz, in introducing the argument just considered, explicitly stated that he was of the "Platonic" opinion that a priori knowledge (at least) is innate and "recollected" (New Essays, Book I). There is a difficulty, however, in knowing how far the doctrine is supposed to range: Leibniz's doctrine that the soul is a monad and that every monad only develops its own inner potentialities, being unaffected by anything outside, implies that in one sense all thoughts, of whatever kind, are innate. This problem involves major questions in the interpretation of Leibniz—in particular, of his views on sense perception. However, it seems reasonable to say that at least in his remarks on innateness in the New Essays Leibniz was distinguishing between kinds of knowledge and ideas, such that some (the pure and a priori) can be said to be innate and others cannot.
Leibniz's remarks were in criticism of the First Book of John Locke's Essay concerning Human Understanding, and they constitute a subtle consideration of the issues lying between rationalism and empiricism at this point. Locke's First Book, although called "Of Innate Ideas," is in fact chiefly concerned with innate principles (and in some part with the alleged innate principles of morality that had been advanced by his adversary, Lord Herbert of Cherbury). Locke considered various characteristics supposed to show that a given proposition is innate (that it is universally believed, that it is assented to as soon as understood, and so forth), and had little difficulty in showing that these are inadequate. He then turned to the consideration that tiny children do not display elaborate conceptions of logic and mathematics such as are alleged by rationalists to be innate. His principle in this instance was "There is nothing in the mind of which the mind is not conscious"; if these conceptions were innate, they would be in the infant's mind, hence it would be conscious of them and (presumably) could display this consciousness. Leibniz, in reply, claimed that this so patently follows that Locke, in insisting on the principle about consciousness, was in effect begging the question: This principle is what the issue turns on. But, as has been seen, this was not how Descartes put the matter. Leibniz here made the cardinal point of the discussion his own non-Cartesian doctrine of subconscious perceptions (connected with his general doctrine of continuity).
debate with empiricism
Once the obvious fact is granted that the allegedly innate ideas do not manifest themselves temporally before other experience, it may be wondered whether any point remains to calling them innate. It has sometimes been suggested that the doctrine of innate ideas merely depends on a confusion between a logical and a temporal sense of "prior." However, this is to underestimate the force of the rationalist claims that the allegedly innate material is such that its operation is a precondition of our learning anything else. It is not easy to decide how to evaluate these claims, as against the central empiricist claim that no such preexisting material need be postulated (the so-called tabula rasa theory of the mind). For one thing, empiricism in its first developments tended to make up for the lack of original raw material by crediting the mind with a very elaborate set of operations. This was evidently the case with Locke, who used such notions as "abstraction," "reflection," and "intuition"; who spoke of "ideas" that are not evidently mere copies from sense perception; and who admitted a nonempirical notion of "substance" and its powers. His position retained a number of rationalist elements. The much more economical apparatus of David Hume, which in effect admits nothing but sensations, their copies, and the operations of association, defines a quite distinctive empiricist theory.
If the debate about innate ideas is cast in terms of a Humean empiricism, there remain principally two issues, one logical and one psychological. The logical issue concerns the question whether highly general concepts, such as those used in mathematics and the sciences, are reducible to or analyzable into those sorts of empirical concepts that can plausibly be said to be derived from sense experience. It would be widely agreed that the answer to this question would be "no." The second, psychological issue is whether the acquisition of concepts, such as occurs in language learning—and this would include even the supposedly straightforward empirical concepts—can be adequately explained by a psychological model postulating only the minimum empiricist requirements of sense perception, retention, association, and so forth. There is influential opinion (held by Noam Chomsky and others) that the answer to this, too, must be "no"; any adequate model may well require stringent innate constraints on the direction and nature of generalization from learning situations. How far these restraints might be supposed to approximate to the rationalists' conceptions of innate ideas—or, in other words, whether the model demands an innate analogue to the possession of concepts—remains to be seen.
If this is indeed an open question, then there is an explicitly psychological version of the rationalist view that is still worth serious consideration. This is not, of course, to say that the innate elements in an adequate model would be likely to correspond to the particular sorts of "ideas" that the rationalists selected for this status—such as the metaphysical notions of God, matter, and mind. Also, there was certainly an endemic confusion, in both the rationalist and the empiricist position on this issue, between psychological and logical issues. Nevertheless, there is still some life in the question, in both its logical and its psychological aspects, the occurrence of the psychological term innate in the original debate not being merely the result of confusion.
It was remarked above that there would now be wide agreement that many general theoretical concepts of mathematics and the sciences do not admit of total reduction to empirical concepts. In contrast with positivist or operationalist views it would be agreed by many that such concepts as "mass," for instance, are not a mere shorthand for sets of possible observation data. Such agreement, however, although it would constitute a rejection of strict empiricism, would not in itself constitute an acceptance of rationalist views about such concepts. It is possible to think that these concepts "transcend," or "go beyond," the empirical merely in virtue of conventional elements—that they are parts of humanly constructed models of reality which relate the observable by imposing a structure on it.
Essential to rationalism, however, is a realistic view (incompatible with even a modified empiricism) about the relation of these concepts to reality and about the necessary relations obtaining between these concepts themselves. The intellectual grasp of these concepts and the truths involved in them is seen as an insight into an existing and unique structure of the world. It is not easy to express this picture (which in varying degrees dominated the rationalists) in less figurative language, but the picture has at least two consequences: that there is a unique set of concepts and a unique set of propositions employing these concepts that adequately express the nature of the world, and that these propositions form a system and could ideally be recognized as a set of necessary truths. There are, admittedly, difficulties about the last point, particularly with reference to Leibniz (these will be considered in the next section). However, something like this general picture is central to rationalism and leads immediately to the question of how anyone can come to know this uniquely correct representation of the world. This invites two more specific questions: What, in general, is the guarantee that knowledge of the world is possible? how can any individual tell in a particular case whether he has hit on some genuine piece of knowledge?
Most rationalists tended to answer the first of the above questions by referring to God; some, but not all, did the same for the second; and they varied in the priority that they assigned to the two questions. Descartes started famously with the second question and found the answer in the "clear and distinct perceptions" of the intellect. Proving, as he supposed, the existence of God via clear and distinct perception, he then employed God's perfection of "being no deceiver" to establish in general terms the reliability of beliefs that went beyond clear and distinct perception. He was, however, so impressed by the thought that it was only in virtue of humanity being created and sustained by God that he could know anything at all, that he was constantly tempted to double back and use the divine perfection to guarantee even the basic clear and distinct perceptions, thus laying himself open to the charge of arguing in a circle.
However this may be, it is notable that in Descartes "clear and distinct perception" is a thoroughly epistemological category. The truths that can be clearly and distinctly perceived do not constitute one homogeneous logical or metaphysical class of truths; the class includes at least statements of contingent existence (his own, in the cogito ) and of necessary existence (that of God), contingent statements about immediate psychological experience, and necessary truths about the relations of ideas. The status of these last, which Descartes called eternal truths, is somewhat obscure. Descartes held, in the Augustinian-Scotist tradition, that they were the products of God's will; but it is left unclear what it is that God has brought about in creating eternal truths, and hence what it is that one knows in knowing them.
the cartesian tradition
The development of the Cartesian tradition within rationalism tended to emphasize to an even greater extent the theological elements in Descartes's theory of knowledge. Thus Nicolas Malebranche retained for the individual case the test of "clear and distinct perception" in a style that seems to assimilate it to moral perception and the promptings of conscience: "One should never give one's complete assent except to propositions which seem so evidently true that one could not reject them without feeling an interior pain, and secret reproaches of the reason" (De la recherche de la vérité, I, Ch. 2; for the moral analogue, see Bossuet, Traité de la connaissance de Dieu et de soi-même, Ch. 1, Sec. 7).
Malebranche gives a strongly Augustinian and indeed Neoplatonist turn to the general account of God's guarantee of the possibility of knowledge. His doctrine was that all our knowledge of the external world is mediated by God; the mind of God contains paradigm ideas in whose form he created the world, and it is these same ideas of which we are conscious when thinking about the world. This is the meaning of Malebranche's saying that we see all things in God. This doctrine, apart from serving religious purposes, was also an attempt to get around the difficulties inherent in Descartes's own causal account of relations between matter and mind (which will be considered more generally later in this entry).
The role of God in the foundations of knowledge takes different and less extreme forms in other areas of the rationalist tradition. The greatest contrast to the Malebranche development of Cartesianism might plausibly be said to be Spinoza's system. It is true that Spinoza did assert that it is the nature of God that guarantees the correspondence of our thoughts to the world, but he so transmuted the notion of God that the doctrine is only verbally similar to Cartesianism. "God" is one name ("Nature" is another) for the one substance, that is, everything that there is. This substance has infinitely many attributes, of which we can comprehend only two, mind and matter. These two attributes are necessarily parallel to one another, and corresponding to any mode of the one attribute there must be a mode of the other. Hence, thought and the material world are inherently adjusted to one another, and the development of knowledge consists in the project of rendering the thought component of this relation as clear (in Spinoza's term, as "active") as possible. It admittedly remains obscure how, within the constraints of Spinoza's determinism, this can be regarded as a "project" at all. Despite this and the other notorious difficulties, Spinoza's system is particularly interesting in the present connection as a thoroughgoing attempt to answer the crucial question that was left very much in the air in Descartes's thought, namely, how any knowledge of a necessary truth, regarded as knowledge of the relations of ideas, could also constitute knowledge of the world.
Leibniz's system, for all its radical differences from Spinoza's, resembles it in one respect having to do with the foundation of knowledge: The general possibility of the correspondence of thought to the world is guaranteed metaphysically by the existence of a correlation between the two. The monads are not affected by anything outside and each develops its own activity from within, but a correspondence between the activities of the monads is given by the "Preestablished Harmony"; and knowledge, the correspondence between "conscious" states of certain monads and other monads, is a special case of this. The Preestablished Harmony, however, depends on God's optimal choice, that is, on God's benevolence. Thus, in a less explicitly epistemological form, Leibniz (in contrast with Spinoza) reverted to the original Cartesian standpoint, in that there is a transcendent and personal God who has a will, and it is a result of his will that there is an ultimate guarantee of the possibility of knowledge.
In general, however, Leibniz was not much concerned with epistemological problems; in particular, he was uninterested in the question that was the starting point for Descartes: How can the individual be certain of the truth of anything? Spinoza was concerned with this question, and tried to develop a theory of knowledge that would avoid the regress latent in Descartes's method, arising from the question of how one knows that one knows. In Spinoza's "degrees of knowledge" it is an essential property of the highest, or intuitive, degree that it is self-guaranteeing. Even so, there is an evident shift in the Spinozistic outlook away from the Cartesian question "What do I know, and how do I know it?" Spinoza, like Leibniz and many other rationalists, gave the metaphysical description of the world from "outside," from a "God's-eye" standpoint rather than from the subjective epistemological standpoint from which Descartes (although unsuccessfully) tried to work. It is, perhaps, a mild irony of the history of philosophy that Descartes's attempt to start with subjective questions of epistemology and to "work out" from there had more influence on the development of empiricism than on later rationalism.
Science and Scientific Method
No attempt will be made here to give an account of the detailed developments of the philosophy of science within rationalist thought, or of the actual scientific conceptions held by or associated with rationalists, although these are of course of great importance, most notably in Leibniz's critique of Cartesian physics and in the development of his concept of force. We shall consider only one or two general points about the rationalists' conception of a completed science and associated notions of scientific method.
Rationalist developments in these matters can usefully be seen in the light of an unresolved conflict within Descartes's system between the method of approaching scientific inquiry and the expected shape of the final product. Descartes favored in principle an approach to inquiry that might be called systematically exploratory. This he called the analytic method; and the straightforward exposition of the results of such an inquiry would be heuristic in style, explaining the resolution of difficulties as they were encountered in the systematic progress. He seems, however, also to have had a picture of a completed science as a complete deductive system, ideally expressed in a unique system of theorems with necessary truths (of a metaphysical character) as its axioms; this he termed the synthetic method of exposition. There is, perhaps, no essential clash between these two ideas of method and result; but Descartes seems not to have been clear about the relation between the two or how this specific method, fully pursued, would yield this specific result. Ambiguities about this question emerge in Descartes's accounts of the role of experiment, in which he sometimes gives the incoherent impression that he is both engaged in logical deduction of scientific laws from self-evident metaphysical premises and doing experiments to assist him in this deduction. On the whole, it is probably better to regard the idea of a complete formally deductive metaphysico-scientific system as less important in Descartes's thought than is sometimes supposed, and to see him as using certain limiting principles of scientific explanation, within which he constructs models to explain particular phenomena.
The idea of the total deductive system, however, had a powerful effect on rationalism and reached its most extreme expression in the work of Spinoza, where the "synthetic" method of Euclidean demonstration is explicitly regarded as necessary to the highest form of understanding. This was not just an expository preference; it was an expression of the basic Spinozistic outlook, which regarded the relation of cause to effect as that of logical ground to consequence—for Spinoza all explanatory relations were logical and timeless. The parallel orders of thought and matter, remarked on earlier, supposedly guarantee that the logical relations of ideas will constitute a totally adequate expression of the nature of the world. (A singular application of this notion of total parallelism is to be found in Ehrenfried Walter von Tschirnhaus, who in Medicina Mentis  argued that an adequate definition of laughter should be able to produce laughter.)
Leibniz, partly under the influence of Erhard Weigel, was also attracted to the "geometrical method." He devoted a good deal of effort to the project of a universal calculus, which would enable arguments on any subject matter to be cast into a rigorous demonstrative form. However, the idea of such a calculus in no way presupposes an ideal of being able to demonstrate scientific truths from metaphysical or other supposedly self-evident axioms, which was the Spinozistic and, on occasion, the Cartesian ideal. Even if Leibniz started with the notion that it should be possible to settle any argument by appeal to the self-evident, he abandoned it in his mature philosophy, in which he made fundamental the distinction between "truths of reason," which can be established by logical insight on the basis of the law of noncontradiction, and "truths of fact," which depend on the principle of sufficient reason and cannot be established on logical grounds alone. There are some notorious difficulties about this distinction, especially concerning the question of the nature of the contingency of "truths of fact," since Leibniz also held the further general principle that in all true propositions the predicate is contained in the subject. It does seem clear, however, that there is an ineliminable contingency about "truths of fact," and hence that the aspiration of reducing all knowledge to a system of deductions from self-evident premises must be impossible in the Leibnizian system.
Francis Bacon said in his Cogitata et Visa (1607), "Empiricists are like ants, they collect and put to use; but rationalists, like spiders, spin threads out of themselves." Bacon, of course, preferred the ants. Although there is some element of truth in the image of the spider, as applied to some rationalist thinkers, it does less than justice to the substantial empirical work done under rationalist inspiration. This is all the more so if one counts Galileo Galilei's view of science as fundamentally rationalist. He certainly rejected any kind of Baconian empiricism and shared the rationalist vision of a mathematical structure of reality that intellectual insight could grasp; but he perhaps had a more sophisticated feeling than any of the philosophers for the balance of imagination and experiment in physics. The rationalist tradition certainly embodied fundamental insights (lacking in empiricism) about the nature of science; above all, it saw the importance of mathematical structures in physical explanation and the vital possibility of a theory's making a conceptual jump beyond the observations and not merely (as in empiricism) an advance in generality. Its sense of the activity of the scientific mind, of its restructuring of observations through concepts and models, was very significant. At the same time, empiricism rightly fought for a clearer distinction between pure mathematics and natural science, undermined the aspirations to final certainty that dogged the rationalists, and emphasized the role of laborious observation and experiment in contrast with the rather dreamlike quality of rationalist visions of the universe. No clearer case exists in the history of philosophy of the need for, and eventual occurrence of, a synthesis; one aspect of that synthesis is neatly summed up in a remark of Giorgio de Santillana that "the true scientist has an empiricist conscience and a rationalist imagination."
Substance and Causality
In the history of classical empiricism the concepts of substance and of active causal power together became progressively weaker and were finally abandoned. Thus Locke employed the full Cartesian array of both material and mental substances, both possessing causal power; George Berkeley banished material substance, partly on the ground that it could not be conceived of as possessing causal activity, which belongs only to mental substance; Hume maintained that the notions of substance and of causal activity are unintelligible. By contrast, in the rationalist tradition the notion of substance has not declined; developments in the idea of causal activity, although partly parallel to the idea of substance, are very different; in general the fortunes of "substance" and of "causal activity" have not been directly linked, as they have proved to be in empiricism—both have undergone considerable and partly independent variations.
In the case of substance (which will be very briefly considered here) the concept has not so much been criticized as used in differing ways to express differing metaphysical views of the world. On one measure, at least, the extremes in this respect are represented by the philosophies of Spinoza and Leibniz. Spinoza gave what he claimed was an a priori demonstration that there could be only one substance (Deus sive Natura, God or Nature); this was intrinsically neither material nor mental, these distinctions arising (as noted above) only at the level of the different attributes of this same substance. Essential to Leibniz's outlook, on the other hand, was an infinite set of substances, the monads, each of them different from all the others. In their character, although there are difficulties of interpretation on this point, they are more of a mental than of a material kind.
On the question of causality an important stream in the history of rationalism stems from the problem left by Descartes, concerning the causal interaction of mind and matter. Descartes's own view, which postulated simple efficient causation as holding between the two types of substance, failed to appeal to even the most ardent Cartesians, and their attention was particularly directed to this question, although difficulties about the meaning of causation even between material bodies also were considered. The natural tendency in the Cartesian tradition was to move toward attributing all causal power to God, and this movement of thought culminated in the doctrine of occasionalism—that both physical and mental events in the world are occasions for the application of God's power, which itself directly produces what would normally be called the effects of those events. This doctrine is most thoroughly expressed in the writings of Malebranche. Similar views, however, are to be found in Louis de la Forge (Le traité de l'esprit et de l'homme, 1666) and Géraud de Cordemoy (Le discernement du corps et de l'âme, 1666), whose work was known to Malebranche.
The theory of occasionalism can be usefully contrasted with Berkeley's empiricist account of causation. For both the only genuine activity was spiritual. For Berkeley the effects of such activity were also spiritual (mind can affect only mind), and indeed there was no other type of substance. The occasionalists retained material substance and did not find it unintelligible that mind can act upon matter; however, they held that the only mind for which such action is intelligible is the infinite mind of God. Here, as elsewhere, the questions of the gulf between mind and matter and of causation as activity emerge as of common concern to both rationalist and empiricist metaphysics, the influence of Descartes being clearly discernible in both.
Another writer who inclined to occasionalism was Arnold Geulincx (Ethics, 1665; 2nd ed., 1675); however, he also suggested a different model for causality, in which God did not, as in occasionalism, make a constant series of miraculous interventions into the natural order but had established ab initio a series of coordinated developments, the relations between which are what is taken for causal interaction. In this connection Geulincx introduced the example of the two clocks, perfectly adjusted to keep the same time, one of which strikes when the other shows the hour; the appearance of causal connection between them is only a result of precise prearrangement.
This same analogy was frequently employed by Leibniz in explaining his own very thoroughgoing version of this thesis, in which all appearance of causal interaction is an instance of the preestablished harmony between the several developments of the monads. Here again there is a notable contrast with and a similarity to empiricism: Both Leibniz and Hume, each representing the culmination of one of the two traditions in its classical form, deny the existence of "transeunt action" between different things and see what is called causation as a correlation between phenomena. Leibniz, however, emphasized some kind of spontaneous activity within the monad, while for Hume neither such activity, nor any notion of a substance, such as a monad, was acceptable. The views of these two philosophers are also worthy of comparison on other subjects, such as space and time; and the points of contact between them are the more significant in the light of the radical and very obvious differences in the spirit, method, and presuppositions of their two philosophies. These differences in the two culminating figures constitute a paradigm, almost a caricature, of the divergent styles of thought associated with rationalism and empiricism, while at the same time similar pressures in the history of thought produced partly parallel developments in each.
See also Alembert, Jean Le Rond d'; A Priori and A Posteriori; Augustinianism; Bacon, Francis; Berkeley, George; Carroll, Lewis; Cartesianism; Chomsky, Noam; Condorcet, Marquis de; Cordemoy, Géraud de; Descartes, René; Diderot, Denis; Empiricism; Encyclopédie; Enlightenment; Experience; Geulincx, Arnold; Herbert of Cherbury; Humanism; Hume, David; Innate Ideas; Kant, Immanuel; Knowledge, A Priori; Leibniz, Gottfried Wilhelm; Locke, John; Malebranche, Nicolas; Neoplatonism; Propositions; Reason; Scientific Method; Scotism; Spinoza, Benedict (Baruch) de; Spinozism; Tschirnhaus, Ehrenfried Walter von; Voltaire, François-Marie Arouet de.
For an understanding of rationalism, writings by and about particular rationalist philosophers should be read; references to these will be found in the bibliographies of the appropriate entries.
Bouillier, Francisque. Histoire de la philosophie cartésienne. 3rd ed. Paris, 1868.
Cassirer, Ernst. The Philosophy of the Enlightenment. Translated by Fritz Koelln and James Pettegrove. Princeton, NJ: Princeton University Press, 1951. As the title indicates, this is not directly on seventeenth-century rationalism but relates to it.
Cottingham, John. Rationalism. London: Paladin, 1984.
Doney, Willis. "Rationalism." Southern Journal of Philosophy, Supp. 21 (1983): 1–14.
Lecky, W. E. H. History of the Rise and Influence of the Spirit of Rationalism in Europe. London: Longman, Green, Longman, Roberts, and Green, 1865; rev. ed., London, 1910.
Santillana, Giorgio de, and Edgar Zilsel. "The Development of Rationalism and Empiricism." In International Encyclopedia of Unified Science. Vol. II. Chicago: University of Chicago Press, 1941.
Windelband, Wilhelm. A History of Philosophy. Translated by J. H. Tufts. New York, 1901. Part IV, Ch. 2; Part V, Ch. 1. Cites the works and—summarily—the views of many philosophers, including minor ones.
philosophy of science
Burtt, E. A. The Metaphysical Foundations of Modern Physical Science, rev. ed. New York, 1952; paperback reprint, Garden City, NY: Doubleday, 1954.
Dijksterhuis, E. J. The Mechanization of the World Picture. Translated by C. Dikshoorn. Oxford: Clarendon Press, 1961.
Gillispie, C. C. The Edge of Objectivity. Princeton, NJ: Princeton University Press, 1960.
innate elements in language acquisition
Fodor, J. A., and J. J. Katz, eds. The Structure of Language. Englewood Cliffs, NJ: Prentice-Hall, 1964. Chs. 21 and 22. Papers by Noam Chomsky and E. H. Lenneberg, respectively.
other recommended titles
Bealer, George. "Modal Epistemology and the Rationalist Renaissance." In Conceivability and Possibility, edited by Tamar Szabo Gendler. Oxford: Oxford University Press, 2002.
BonJour, Laurence. In Defense of Pure Reason. Cambridge, U.K.: Cambridge University Press, 1998.
BonJour, Laurence. "A Rationalist Manifesto." Canadian Journal of Philosophy, Supp. 18 (1992): 53–88.
Brink, David. "Kantian Rationalism: Inescapability, Authority, and Supremacy." In Ethics and Practical Reason, edited by Garrett Cullity. New York: Clarendon Press, 1997.
Carruthers, P. Human Knowledge and Human Nature. Oxford: Oxford University Press, 1992.
Gendler, Tamar Szabo. "Empiricism, Rationalism, and the Limits of Justification." Philosophy and Phenomenological Research 63 (2001): 641–648.
Markie, Peter. "Rationalism vs. Empiricism." Stanford Encyclopedia of Philosophy. Available from http://www.plato.stanford.edu.
Peacocke, Christopher. The Realm of Reason. Oxford: Clarendon Press, 2004.
Peacocke, Christopher. "Three Principles of Rationalism." European Journal of Philosophy 10 (2002): 375–397.
Bernard Williams (1967)
Bibliography updated by Benjamin Fiedor (2005)
Rationalism comes in various versions and makes wider or narrower claims. The idea underlying most versions is that reason is the most characteristic faculty of Homo sapiens. Appeal to reason is part of traditional wisdom, yet traditional (ancient Greek) rationalism includes an out of hand dismissal of traditional wisdom. The modern version of this dismissal is the radical demand for starting afresh (Enlightenment radicalism) and admitting only ideas that are proven, absolutely certain, and fully justified by rigorous proof. Science begins with rejecting all doubtful ideas. Francis Bacon initiated the idea that traditional unfounded views are the causes of all error; René Descartes tried to ignore all doubtful ideas and start afresh from nothing. David Hume began his investigations in efforts to delineate all that is certain while ignoring all else; he and many others, from Denis Diderot to Pierre Simon de Laplace, took it for granted that Isaac Newton’s success was due to his adherence to Bacon’s advice. Auguste Comte and T. H. Huxley took it for granted that other fields will be as successful if they only jettison tradition more fully; Ludwig Wittgenstein went further and said only scientific assertions are grammatical (positivism, scientism).
ENLIGHTENMENT RADICALISM AND THE ROMANTIC REACTION
Yet what proof is no one knew. Mathematics was the paradigm of proof, and the success of physics was largely ascribed to its use of mathematical methods, a practice for all to emulate. What is that method, and how can it be applied to the social domain? How does the relinquishing of tradition help word theories mathematically? This was unclear even after the discipline of statistics was developed enough to become applicable to some social studies (as in the work of Adolphe Quételet, 1796-1874). Yet clearly as usefulness gives rational thought its initial (even if not final) worth, at least the rationality of action is obvious: its goal-directedness. Hence the study of rationality is vital for the study of the rational action that is the heart of the study of humanity. Whereas students of nature seldom pay attention to the rationality and the scientific character of their studies, students of humanities are engrossed in them. And whatever their views on this rationality, at least they openly center on it. Thus in the opening of his classic An Inquiry into the Nature and Causes of the Wealth of Nations (1776), Adam Smith declares his intent to ignore irrationality, no matter how widespread it is. Slavery is widespread, yet everyone knows that putting a worker in chains is no incentive, he observed.
The Enlightenment movement deemed Smith’s argument obvious; this led to its dismissal of human history as the sad story of needless pain caused by ignorance and superstition. This was an error. The advocacy of the abolition of slavery came in total disregard for its immediate impact on the lot of slave owners. Smith spoke of rationality in the abstract. Because high productivity depends on the division of labor and because this division leads to trade, freedom is efficient. Selfish conduct is rational as long as it is scientific, that is, undogmatic. Life in the light of reason is egalitarian, simple, and happy. This abstract reasoning led to concrete results, including the French Revolution and its terror and wars. Edmund Burke and Georg Wilhelm Friedrich Hegel blamed the radicalism of the revolution for its deterioration into terror. The reaction to the French Revolution was aggressively hostile to radicalism, to egalitarianism, and even to reason (Hegel).
Karl Marx wedded the two great modern movements, the radical Enlightenment movement and the Romantic reaction to it. The former had the right vision, and the latter had the historically right view of the obstacle to its realization. Smith-style harmony between individual and society has no place in traditional society. Hence the institution of enlightened equality is an essential precondition for it. The realization of the radical dream of harmony requires civil war. But it is certainly realizable, he insisted.
Marx’s critique of radicalism from within is as popular as ever. We are chained to our social conditions, and rationalism cannot break them. Max Weber, the author of the most popular alternative to Marx’s ideas, stressed this; so do all the popular radical critics of the ills of modern (“bourgeois”) society, chiefly imperialism, racism, and sexism, perhaps also alienation from work. These critics puzzle the uninitiated, as they seem to belabor condemnations of obviously indefensible aspects of modern society. But they do something else; they advance a thesis. Social evils will not go away by sheer mental exercises. Are there any reasonable people who disagree with this thesis? It is hard to say. Perhaps some thinkers still follow the central thesis of the Enlightenment movement. If such people do exist (as seems true but not obviously so), then they are the neoliberals, the Chicago school of economics, which is not confined to economics, as it preaches the idea that a world with free markets still is the best of all possible worlds, even though it is far from ideal (Friedrich A. von Hayek).
What then is rationalism? Of the alternative views on reason, which can count as variants of rationalism? Consider pragmatism, the view of the useful as the true (Hegel, William James, John Dewey). It is unsatisfactory, because assessments of usefulness may be true or not; but is it a version of rationalism? Consider the traditionalist reliance on the test of time (ordinary-language philosophy; neo-Thomism). The assessment of the relative worth of traditions may be cultural (Martin Buber, Amitai Ezioni; communitarianism) or intellectual (Michael Polanyi, Thomas S. Kuhn; postcriticalism). It is unsatisfactory, as these assessments may be true or not; but is it a version of rationalism? There is no telling. The same holds for appeals to other criteria for truth. These are common sense (Hume, Smith, Thomas Reid, Adam Ferguson, George Edward Moore), the intuitions of Great Men (Johann Gottlieb Fichte, Hegel, Martin Heidegger), higher religious sentiments (Friedrich Schleiermacher, Fyodor Dostoevsky, Leo Tolstoy), and superior tastes (Richard Rorty). Are these variants of rationalism? Do they lead to more reasonable human conduct? The standard claim is that their asset is in their ability to maintain social stability. But in the early twenty-first century stability is unattainable and even deemed inferior to democratic controls (Karl R. Popper).
There is no consensus about whether the counsel to limit reason and admit religion is rationalism proper (Moses Maimonides, Saint Thomas Aquinas, Robert Boyle, Moses Mendelssohn, Polanyi) or not (Immanuel Kant, David Strauss, Ludwig Feuerbach, Sigmund Freud, Bertrand Russell, Adolf Grünbaum). The only consensus is about the defiance of reason (Søren Kierkegaard, Max Stirner, Joseph Arthur Comte de Gobineau, Georges Sorel, Friedrich Nietzsche, D. H. Lawrence, Heidegger, perhaps also Paul Feyerabend). The only generally admitted necessary condition for rationalism is the demand to side with reason. Therefore it is fashionable to limit rationalism by allowing the taking of a single axiom on faith while otherwise swearing allegiance to reason (Polanyi, Richard H. Popkin, Pope John Paul II; fideism). The default view should then be that this allegiance suffices. Add to this the consensus around a necessary condition for this allegiance. It is the critical attitude, openness to criticism, the readiness to admit the success of the criticism of any given view. Consider the view that the critical attitude is sufficient as the default option (Popper) and seek valid criticism of it that may lead to its modification, to the admission of some unavoidable limitations on reason, whether in the spirit of Marx or in that of his critics. The need for this limitation comes from purely philosophical considerations. Hume said that we need induction for knowledge and for practice, yet it is not rational (it has no basis in logic); instead, we rely on it out of habit and necessity and this is the best we can do. A popular variant of this is that because induction is necessary, it is in no need of justification (Kant, Russell). Another variant takes it on faith (Polanyi, Popkin; fideism). Is induction really necessary?
This question is welcome. Since finding alternative answers to a worthy question improves their assessment, they are all worthy. Hence all versions of limited rationalism are welcome—as hypotheses to investigate (Salomon Maimon, Popper). This is the power of the method of always trying out the minimal solution as the default.
Critical rationalism is revolutionary because it replaces proof with test; it replaces radical, wholesale dismissal of ideas with the readiness to test piecemeal (Albert Einstein, Popper; reformism). The demand to prove thus yields to the critical attitude (William Warren Bartley III, Willard Van Orman Quine; non-justificationism), recognizing that theories possess graded merit (Einstein, Leonard Nelson, Popper; critical rationalism)—by whatever rule we happen to follow, no matter how tentative. Rules are then hopefully improvable (Charles Sanders Peirce, Russell, Popper; fallibilism). Hence diverse rules may serve as competing criteria or as complementary. Being minimalist, critical rationalism invites considering some older theologians as allies, although not their contemporary followers. Unlike radical rationalism, critical rationalism is historically oriented. (It is the view of rationality as relative to contexts and of truth as absolute, as a guiding principle à la Kant.)
This invites critical rationalism to enlist rational thought as a category of rational action (Ian C. Jarvie and Joseph Agassi). And this in turn invites the study of rationalism as an aspect of extant scientific research. It also invites comparison of the various versions of rationalism as to the degree of their adequacy to this task: take scientific research as it is, warts and all, and examine its merits and defects according to the diverse alternatives. This attitude is new and expressed in various studies of the sociology of science, so-called, that often spread over diverse disciplines, including political science and even criminology no less. This renders a part of the project of rationalism the assessments of the intellectual value of the outcome of research, theoretical, practical, or cultural—or even aesthetic. The only intellectual justification of a scientific theory, said Einstein, is its ability to explain; its best reward is its successor’s admission of it as approximate. In this way he stressed that the aim of research is to explain in the hope of approximating the truth. This is open to debate. Social science as a whole may serve as a test case, with the sociology of science at the center of the debate on this matter.
Historically, rationalism doggedly accompanied studies of nature, not social studies. What in these should rationalism approve of? Discussion of this question allowed rationalism to inform the social sciences. A conspicuous example is the vagueness in social studies of the boundaries between philosophy, science, and practice that still invites open discussion. Anything less is below the minimal criterion of the critical attitude.
Critics of minimal rationalism find criticism insufficient, since positive criteria of choice need justification. If so, then rationalism is back to square one. If not, then positive criteria must be tentative, and the issue must shift from their justification to efforts at their improvement. Some do not like this, as it rests on their initial choice that was too arbitrary. They prefer to return to the initial criterion and replace it with the least arbitrary one. They are radicals. The clash is thus between the radical and the critical version of rationalism—as well as between them and fideism.
The agenda of rationalism—in philosophy, in science, or in practice—is the same: heightening the critical attitude, seeking improvement through criticism everywhere. Where is the starting point? How are we to decide on our agenda? Parliamentary steering committees decide on agendas. The commonwealth of learning, however, is its own steering committee. Those concerned to promote rationalism should do their best to put discussions of it high on the public agenda.
Agassi, Joseph. 1996. The Philosophy of Science Today. In Philosophy of Science, Logic, and Mathematics in the Twentieth Century. Vol. 9 of Routledge History of Philosophy, ed. Stuart G. Shanker, 235-265. London: Routledge.
Agassi, Joseph, and Ian C. Jarvie, eds. 1987. Rationality: The Critical View. The Hague: Nijhoff.
Burtt, E. A. 1926. The Metaphysical Foundations of Modern Physical Science. London: Routledge.
Churchman, C. West. 1968. Challenge to Reason. New York: McGraw-Hill.
Einstein, Albert. 1954. Ideas and Opinions. New York: Bonanza Books.
Festinger, Leon. 1957. Theory of Cognitive Dissonance. Stanford, CA: Stanford University Press.
Feyerabend, Paul. 1987. Farewell to Reason. London: New Left Books.
Haakonssen, Knud, ed. 2006. The Cambridge History of Eighteenth-Century Philosophy. 2 vols. Cambridge, U.K.: Cambridge University Press.
Hayek, Friedrich August von. 1952. The Counter-Revolution of Science: Studies on the Abuse of Reason. Glencoe, IL: Free Press.
Hayek, Friedrich August von. 1960. The Constitution of Liberty. Chicago: Chicago University Press.
Jarvie, Ian C. 1964. The Revolution in Anthropology. London: Routledge.
Jarvie, Ian C., and Joseph Agassi. 1987. The Rationality of Magic. In Rationality: The Critical View, ed. Joseph Agassi and Ian C. Jarvie, 363-383. The Hague: Nijhoff.
Koyré, Alexandre, 1968. Metaphysics and Measurement. London: Chapman and Hall.
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A theory or system that exaggerates reason's independence from the senses in philosophy or from supernatural revelation in religion. Although it appears in many forms, in nearly all a doctrinaire insistence on the sovereignty of reason displaces a native trust in the reasonableness of human thought, and an arbitrary insistence is placed on the former as uniquely representative of free scientific inquiry. This article treats first of philosophical rationalism, giving its historical outline and characteristics, and then of religious rationalism, both negatively as denying the supernatural and affirmatively as an aid to understanding revealed truth.
Philosophical rationalism is commonly associated with certain philosophers of the 17th and 18th centuries in Continental Europe, notably R. descartes, B. spinoza, and G. W. leibniz. Generally it holds that reason rather than sense experience is the source of knowledge and the ultimate test of truth. Its opposite is empiricism or positivism, which maintain that ideas and propositions not directly verifiable by sensory observation are meaningless. Usually rationalistic knowledge is thought to originate in reason itself, being a system of universal and necessary truths based on principles or starting points not discovered in experience.
As an attitude of mind resulting from philosophical positions, rationalism tends to single out and magnify abstract human reason while minimizing other human powers, such as sense, imagination, and free will. Logical ideals of order, procedure, and method predominate over empirical data and experimental technique. As a philosophical position, rationalism usually involves the following theories relating to being and knowledge, methodology, and sufficient reason.
Being and Knowledge. Most rationalist systems rest on Plato's theory of a dual universe, wherein eternal, necessary truths somehow exist apart from the world of human experience but remain accessible to human reason. This concept of a "duoverse" was further developed by Descartes, who considered material substances or extended bodies in mechanical motion as independent units, distinct and separate from spiritual substance or thinking mind. Even in man, the meeting place of the two realms of body and spirit, this separation held.
Hence, for neither Plato nor Descartes could the material world of sense experience be a source of genuine knowledge. Adopting a theory of innate ideas, Plato's epistemological rationalism held that human reason had "seen" in a previous existence the necessary and eternal truths. By recollection of these ideas, the mind obtains real knowledge even though it is surrounded by a shadow world of change that is basically unintelligible. Plato's Socratic dictum, "Virtue is knowledge," also founded a type of ethical rationalism.
Descartes's theory was more complex and did not involve the Platonic notion of recollection. He thought of the human mind as born with the materials of knowledge, e.g., certain fundamental concepts such as "God," "being," "soul," "material substance," "cause," "number," "time," "space," and "motion," as well as general propositions such as "I think, therefore I am"; "Every event has a cause"; and "God is perfect and cannot deceive me." These, as well as the basic truths of ethical obligation, are discovered in the mind itself and not in extramental reality, even though experience may help clarify and make explicit what the mind contains (see innatism). Derided by empiricists as empty a priori forms, these, for the rationalist, were the starting points of deductive movements of the mind toward further truths, including the results of applying universal concepts to empirical data. Descartes, for instance, could build on them an argument for the existence of a material world otherwise not known with certainty to exist. For him, the truths of faith were not among the certitudes of reason, but depended rather on the will—a position designed to safeguard the supernatural but later to lead to religious rationalism and the denial of revealed truth.
Some types of rationalism admit that ideas are supplied to reason either from sense experience or in self-reflection. Reason, however, still functions to discover real knowledge by seeing relations and necessary connections or by deducing further consequences from the resulting intelligibility. Some rationalists think of reason as an instrument for bridging the gap between itself and reality. For them, knowledge is attained by applying to experience concepts or meanings discovered in reason. Characteristic of all such rationalism is the tendency to view ideas or concepts rather than things themselves as the objects of thought. For thinkers such as I. kant and G. W. F. hegel, the gap between the meanings of reason and the things of experience stimulated a critical rationalism that ultimately reduced all of reality to reason and absolute mind.
Besides attempting to deduce from fundamental laws of logic the basic propositions of a universal system of knowledge, Leibniz developed a rationalist theory that depended explicitly on the existence and functioning of an infinite intelligence.
Methodology. Mathematics, with its clear and distinct ideas and rigorous demonstration, was the ideal knowledge and method for most rationalists. Seventeenth-century scientists such as J. kepler, G. galilei, and, later, I. Newton devised physical theories that were heavily mathematical in character. As their new and powerful method for describing the physical universe was perfected, philosophers tried to introduce the rigor of mathematics into every department of knowledge. H. grotius is a good example of this, with his secularization of law. As rationalists, these thinkers tended to narrow their conception of genuine knowledge to that obtained by the methods of physical science, restricted though these may have been.
Spinoza and Leibniz exemplify attempts to solve a crucial problem that immediately came into focus, namely, how to use such methods to construct a rationalistic system that could embrace mind and God as well as matter. Boundless confidence in the power of reason for a time overcame the natural repugnances these systems encountered from common sense. In the end there was no escaping the fact that such methods had nothing to say about the meaning of man, of human values, and of freedom, none of which exhibit mechanical or mathematical characteristics.
But some popularizers of the new learning unreasonably concluded that what these methods could not treat did not exist, and they somehow won for themselves the title of rationalists, combining a valid rejection of prejudice, ignorance, credulity, and superstition with an irrational rejection of revelation and religious authority.
Others refused to straitjacket the mind in the mathematical-physical method, and kept philosophy open to genuine knowledge of man, God, and freedom. This tension continued into the 18th-century Age of the Enlightenment, with its practical applications of rationalism to questions of authority in religion, theories of government in politics, and further developments of method in science. In the common confusion between philosophical rationalism and the new scientific methods, older philosophers and overzealous Churchmen, conscious of the philosophical errors in rationalism, condemned the new science as erroneous philosophy and acted at times to interfere with free scientific inquiry.
Sufficient Reason. One of Leibniz's followers, C. wolff, sought to advance philosophical knowledge by transferring the new ideals of method and some of its nonphilosophical procedures into metaphysics, philosophy of man, and ethics. He accepted Leibniz's distinction between "truth of fact" and "truth of reason," and made extensive use of the principle of sufficient reason to transform all contingent elements to rational elements, thus attempting to bridge the chasm between experience and reason. This resulted in a rationalistic system wherein each form of empirical knowledge, such as physics or psychology, was supplemented by a corresponding rational form that functioned to raise the former to the level of genuine knowledge by deducing it from the principles of general ontology and cosmology.
Wolff's voluminous work was condensed into handy manuals by his followers, who embodied his basic rationalistic view of a duoverse and the deductive ideal of a system of knowledge. These were widely used in Protestant seminaries and universities and became well known to scholastics. Philosophy textbooks modeled on Wolff's were produced by German Jesuits between 1750 and the suppression of the Society of Jesus (1773), and the work was continued by Franciscans and others who imitated Wolff's scholasticism. Catholic manual writers were to come under the influence of such German rationalism as late as the 20th century. In the absence of adequate historical studies of scholasticism at the time, this type of rationalism was considered to be genuinely scholastic and led many to accept its demolition by Kant as a final destruction of scholastic philosophy [see J. E. Gurr, The Principle of Sufficient Reason in Some Scholastic Systems, 1750–1900 (Milwaukee 1959)]. Many theology manuals followed a similar method, beginning with definitions of theological realities and then seeking a greater insight by relating concepts or by analyzing definitions to discover their full logical implications.
Kant, who was nurtured on this kind of philosophical rationalism, set out to destroy it; at the same time he wished to safeguard ultimate truths about man and God with a new critical, as opposed to a dogmatic, rationalism. His attempts to remove such truths from the sphere of reason, however—since they neglected the native, spontaneous reasoning powers of the human mind—actually dissolved the rational basis of faith and morals and led eventually to advanced forms of religious rationalism.
Religious rationalism has both a philosophical and a social dimension. As derived from philosophical rationalism, it is a negative and limited view of reason as supremely competent in matters of faith and morals. Thus it holds that an adequate theory of man, of his relations with God, and of his destiny can be had from human intelligence alone; it thereby excludes revelation and the evidence of any authoritative witness. As resulting from the positive use of reason to penetrate, understand, and defend truths known by faith, religious rationalism is a form of theological activity.
Negative Aspect. Early Greek thinkers who rejected explanations of the world of experience in terms of the gods and goddesses of mythology to substitute the principles and causes of philosophy were rationalists without being antireligious. Rationalist elements—in the sense of questioning existing institutions and ways of doing or thinking, or of criticizing abuses, real or imagined—are present in the oldest Biblical documents.
But modern religious rationalism—from the Averroists of the late Middle Ages, through the humanists of the Reformation and the philosophes of the Enlightenment, to 20th-century evolutionists—mutilates by its negations the power of reason to range beyond finite personality and the natural world. The present narrow form of this doctrine is scientism, which teaches that the natural sciences study all of reality and that their methods are the only valid way to knowledge.
As involving practical conflicts between Church authorities and those who confuse scientific method with metaphysics, rationalism is itself an ideology finding expression in a sustained war on prevailing creeds and institutions, whether these be Catholic, Protestant, or Jewish. English deists such as J. locke, whose influence still is felt in freemasonry, and French encyclopedists such as P. bayle and voltaire personify this ideology. These men were committed to eliminating from Christianity, in the name of sovereign reason, whatever was above human comprehension. Biblical accounts of creation, God's dealings with the Jews, miracles, the Incarnation, the Resurrection, prayer, providence, and a divine teaching authority in the Church were all refused credence. In Germany and France the enlightenment (Ger. Aufklärung, or clearing up) aimed at banishing all mystery and the supernatural, specializing in the application of restricted standards of reason to art, literature, and political and social activity. On Nov. 10, 1793, this practical doctrinaire rationalism culminated in the French National Convention's selecting a Madame Maillard to represent the goddess of reason and enthroning her in the Cathedral of Notre Dame in Paris—designated for a time as the Temple of Reason.
By the end of the 1800s, antireligious rationalism manifested itself in various forms of naturalism, positivism, scientism, secularism, and materialism. In a less sophisticated form it still survives as a kind of folklore tradition that (1) reason in an age of science has demolished all forms of spiritual and supernatural reality and knowledge; (2) only rationalism inspires hatred of hypocrisy and teaches moral and intellectual honesty, inspiring courage in the fight for social justice; and (3) only those who deny Christianity, and embrace atheism are true rationalists.
Positive Aspect. Religious or theological rationalism may also refer to the fact that the Jewish, Muslim, and Christian religions, although based on divine revelation, expect reason to perform its natural work of inquiry, consideration, and formulation. This results in a theological expression of revealed truth, an organized effort to understand what one believes, sometimes referred to as rationalistic theology. From the early Apologists of the 3d century, through nicholas oresme to L. E. M. bautain, the Catholic Church has condemned thinkers who unduly minimize reason; similarly, theological systems holding that revelation has been given man as a substitute for all other knowledge have been rejected. The distinction between reason and faith has been steadily maintained, however, and when these are seen in proper relation, the individual believer is free to use understanding and reason in many ways. St. Paul's reference to inexcusable ignorance of the existence of God (Rom 1.20) itself initiated an untiring effort to blend religious faith with rational speculation. Catholic theology, as a consequence, presupposes the truths of natural reason as preambula fidei.
Medieval Thought. For St. Augustine, the perfect kind of rational knowledge was the philosophy of Plato and Plotinus. St. anselm of canterbury regarded logical knowledge as true rational knowledge, but his Credo ut intelligam implied that, with faith as a necessary condition, a deeper understanding of religious truth could be achieved by the application of reason. His ontological argument for the existence of God was rationalistic, however, in the sense that it proceeded independently of natural experience, although within the context of faith and the truths guaranteed by authority.
Pope Pius IX, in the 19th century, defended the scholasticism of the high Middle Ages against the suspicion of rationalism raised by A. bonnetty, maintaining that "the method which St. Thomas and St. Bonaventure and other scholastics after them used does not lead to rationalism …" (H. Denzinger, Enchiridion symbolorum, ed. A. Schönmetzer, 2814). Yet the use of Aristotelian dialectic in medieval scholasticism did give birth to a system of purely rational truth out of which modern philosophy was to be born.
Unlike the Jewish philosopher Moses maimonides, the Muslim Averroës stressed that philosophy should be kept apart from theology. He justified a complete separation on the rationalistic principle that what was necessarily and genuinely true in philosophy could contradict the teaching of Christian revelation, in his case, the Qur’ān (see double truth, theory of). Christian theologians such as siger of brabant promoted a Latin averroism that the condemnations of 1270 and 1277, by Étienne tempier, Bishop of Paris, could not completely eradicate. This influence continued through the Averroistic Aristotelians at Padua to the libertines of the 17th and 18th centuries.
Reformation. Among Protestants, P. melanchthon developed a Christian rationalism designed to meet the age-old need of understanding what was known by faith. In Italy, socinianism exemplified a Protestant rationalist position in theology that was destructive of the revealed doctrine of the Trinity. Similarly, in 18th-century Germany, Protestant theologians accepted a distinction proposed by J. S. Semler between religion (understood more as an ethics) and theology, together with a similar separation of religion from theological opinion and religious usage fostered by J. G. herder. Such distinctions, made originally to safeguard religion from attacks on theology and Biblical history, led eventually to a disavowal of the true supernatural nature of revelation as the word of God. It left reason and its resources supreme and, by the end of the 19th century, led to the very antireligious naturalism that Protestant theological rationalists had sought to prevent.
Meanwhile, F. D. E. schleiermacher maintained that religion consists in neither knowledge nor action, but rather in the consciousness of absolute dependence on God. Thus he replaced the Church by a purely individual commitment and opened the way to a philosophy of power that was fatal to both rationalism and Christianity. These developments provided scriptural exegetes with new critical principles whose application led to extremes of naturalism in such works as the Leben Jesu of D. F. strauss.
Modern Thought. Nineteenth-century Catholic theologians such as G. hermes and A. gÜnther attempted unsuccessfully to relate Catholicism to the pure rationalism of post-Kantian philosophy. But with God, reason, and faith united in the Hegelian system, they could not avoid reducing faith to a work of unaided reason, thereby denying the gratuity of revealed truth. The Danish Lutheran, S. A. kierkegaard, on the other hand, gave attractive expression in his writings to an acceptable position; this regards faith as a personal commitment that neither results from a rationalistic (or historical) mode of argumentation nor is a rational exercise associated with the unfolding of Absolute Mind.
The failure of some contemporary Catholic writers to represent adequately the Catholic view of the relationships between faith and reason and between theology and philosophy has caused reactions against rationalist philosophy to be interpreted as attacks on thomism or on other scholastic syntheses. Some of the literature of existentialism augments this confusion, for its horror of the systematized and the objectivized is basically an aversion from the excesses of rationalism.
Critique. Both philosophical and religious rationalism must be criticized for neglect of evidence. Philosophical rationalism fails to take into account prephilosophical and prescientific knowledge, tending to consider specialized attitudes or techniques as the only rational method. Religious rationalism too often simply makes an act of faith in the all-embracing character of a currently successful method of knowing; it refuses even to consider the data of revelation, and thus cuts itself off completely from the highest source of human knowledge.
See Also: reasoning; kantianism; deism; theism.
Bibliography: f. c. copleston, History of Philosophy (Westminster, Md. 1946–); v.4, Descartes to Leibniz; v.5, Hobbes to Hume (1959); v.6, Wolff to Kant (1960). c. constantin, Dictionnaire de théologie catholique, ed. a. vacant et al., 15 v. (Paris 1903–50) 13.2:1688–1778. c. mazzantini, Enciclopedia filosofica, 4 v. (Venice-Rome 1957) 3:1870–83. o. muck, Lexikon für Theologie und Kirche, ed. j. hofer and k. rahner, 10 v. (2d, new ed. Freiburg 1957–65) 8:1005–06. k. oehler and h. hohlivein, Die Religion in Geschichte und Gegenwart, 7 v. (3d ed. Tübingen 1957–65) 5:790–800. r. eisler, Wörterbuch der philosophischen Begriffe, 3 v. (4th ed. Berlin 1927–30) 2:579–84. a. w. benn, The History of English Rationalism in the Nineteenth Century, 2 v. (New York 1962). j. b. bury, A History of Freedom of Thought (2d ed. New York 1952). É. h. gilson, Reason and Revelation in the Middle Ages (New York 1961). g. boas, French Philosophies of the Romantic Period (New York 1964). j. d. collins, God in Modern Philosophy (Chicago 1959) 55–89. r. derathÉ, Le Rationalisme de Jean-Jacques Rousseau (Paris 1948). j. m. f. laporte, Le Rationalisme de Descartes (Paris 1945). p. hazard, The European Mind (1680–1715), tr. j. l. may (New York 1963). j. s. spink, French Free-thought from Gassendi to Voltaire (London 1960). l.i. brevold, The Brave New World of the Enlightenment (Ann Arbor 1961). a. bremond, Religions of Unbelief (Milwaukee 1939). m. c. d'arcy, Belief and Reason (London 1944).
[j. e. gurr]
In the final section of the Critique of Pure Reason, Immanuel Kant distinguishes empiricism and rationalism:
In respect of the origin of the modes of "knowledge through pure reason," the question is as to whether they are derived from experience, or whether in independence of experience they have their origin in reason. Aristotle may be regarded as the chief of the empiricists, and Plato as the chief of the noologists [rationalists]. Locke, who in modern times followed Aristotle, and Leibniz, who followed Plato … have not been able to bring this conflict to any definitive conclusion. [Kemp Smith, trans.]
Kant's vision of a conflict between empiricism and rationalism remains to this day the organizing principle for discussions of early modern metaphysics and epistemology. Kant may have overstated the extent to which there was a conflict between empiricists and rationalists: it has recently been suggested that both may be seen as pursuing the common project of defining the scope and limits of human knowledge. It has also been charged that the very distinction between empiricism and rationalism should be rejected. I believe that the distinction usefully captures certain defining features of early modern philosophy and that the terms rationalism and empiricism should be retained.
Kant's characterization of rationalism is generally accurate. One addition must be made. Like most early modern philosophers, the rationalists conceived of the human cognitive faculties as distinguished into the pure intellect, the senses, and the imagination. The pure intellect was the faculty that enabled human beings to gain knowledge. Rationalism may be defined as the view that substantive truths about the nature of reality may be derived from the pure intellect alone, operating independently of the imagination and the senses.
The Roots of Rationalism
It was by no means idiosyncratic for Kant to take Plato and Aristotle as prefiguring the opposition between rationalism and empiricism; this opposition is, for example, the organizing principle of Raphael's Vatican fresco The School of Athens. Plato points up, to the realm of Forms, the unchanging objects of the pure intellect; Aristotle points to the earth, thereby indicating the experiential origin of knowledge. Plato's commitment to the existence of unchanging truths, sharply contrasted with the variable images of the senses, marks him as the grandfather of early modern rationalism.
Approximately five hundred years later, Saint Augustine synthesized Plato's philosophy with the Christian religion in order to provide the latter a philosophical underpinning. Augustine found in Plato a remedy for the vagaries of sense experience that threatened the truth of Christianity; his work remained seminal for the early modern rationalists: Descartes, Leibniz, and Malebranche, believers all, explicitly hearkened back to Augustine. Aristotle's work, however, held its importance for medieval philosophers. He became known as "the Philosopher," and his thought, especially as interpreted by Aquinas, became the official philosophy of Christianity.
Descartes formulated his conception of philosophy in explicit opposition to the Scholastic Aristotelians' emphasis on sense-based experience. The Meditations are best understood as a series of cognitive exercises that train the meditator to discover truths about the world by the use of pure intellect, independent of the senses. Beginning by purging the self of intellectual preconceptions, by doubting all knowledge hitherto received through the senses, the meditator rebuilds knowledge, achieving clear and distinct ideas of the nature of the soul, God, and body.
The Meditations was not a complete system of philosophy; it only laid the foundation for Descartes's broader philosophical project. Descartes explains in a letter to his friend Marin Mersenne that "my little book on metaphysics contains all the foundations of my physics." The point of the Meditations was to reconceptualize the physical world as a realm of extension, governed by laws of motion, and therefore amenable to mathematical investigation. Descartes envisioned his physics very broadly, extending his view from celestial bodies to terrestrial bodies, the operations of animals, and the nature of the human being. He meant for his scientific project to culminate in the Principles of Philosophy, which remained unfinished, although the broad lines of Cartesian science may be derived from other works.
Although Descartes turned to philosophy (metaphysics) in order to ground science and thought that the only genuine knowledge that human beings could achieve derived from the intellect operating independently of the senses, he nevertheless retained an important place in science for the senses. General truths about body only specify the possible range of explanations of physical phenomena; in order to determine the particular explanations, one must appeal to sense experience. Cartesian rationalism remains limited to the most general truths about the universe.
Spinoza is the only Jewish thinker among the rationalists. He was excommunicated from the Jewish community of Amsterdam, possibly on account of the heretical views that he held about the nature of God and the immortality of the soul, views later elaborated in his great systematic work, the Ethics. Spinoza's philosophical system is the purest example of rationalism.
Other rationalists remained committed to the truths of revealed religion; Spinoza maintains that the Bible does not contain the word of God, but is a work of men that serves the sociopolitical ends of establishing and securing the commonwealth. In his Theological-Political Treatise, Spinoza therefore argues that human beings should be free to hold whatever religious views they like, provided they do not upset the established civil order.
This work is a prolegomenon to the Ethics, where, on the basis of reason alone, Spinoza radically reconfigures traditional notions of God, nature, and morality. Rejecting all sensory inputs as mere "random experience" that do not reveal the nature of the world, he says there is only one substance, which he strikingly calls "God or nature." All existing things must be understood to be merely modifications of that single substance, not substances in their own right. One of the most provocative aspects of Spinoza's vision of the universe, which drew sustained criticism from his contemporaries, is his claim that all events are determined by God to occur. Indeed, he maintains, even God does not freely choose to create the world—this in sharp contrast to traditional views of God as creator—but is determined by his own nature to produce what exists in the world. This determinism renders the structure of nature intelligible to the human intellect.
By understanding the necessary and eternal order of the world, humans may come to understand both their place in the world and what they ought to do in the world. By achieving this understanding, they may achieve a kind of nontheological immortality. Their reason, which grasps the unchanging and eternal order of nature, enables them to achieve a kind of immortality as well.
Malebranche's philosophical system is a synthesis of Cartesian philosophy and Augustinian theology. In The Search after Truth, Malebranche seeks to remedy human ignorance by presenting the nature of the human mind and showing that it is only by heeding the perceptions of the pure intellect that human beings may achieve knowledge. In the course of elaborating this view, Malebranche develops his two most distinctive doctrines: the vision in God and occasionalism.
The vision in God is Malebranche's account of human knowledge of truths about the world. He claims that human beings may cognize general truths because they have access to those truths in God's mind; they must have access to truths in God's mind because general truths are eternal and infinite and therefore could not be contained in the finite human mind. Occasionalism is a general account of causation, according to which no finite being (whether a mind or a body) is the real cause of any change in the world. Malebranche maintains that a real causal connection must be one that is necessary; however, there is a necessary connection only between God's will and some effect. Consequently, apparent causes are merely occasions for the exercise of God's causal power in accordance with the natural laws constitutive of nature.
In the Treatise on Nature and on Grace, Malebranche deploys these doctrines in order to explain God's action in the created world. He seeks to show that the seeming imperfection of the natural world manifest in natural disasters and the birth of monsters, and the apparent inequality in God's distribution of grace, are merely apparent defects. Because God acts in accordance with general laws, and does not intervene directly to produce particular events, his action in the realms of nature and grace is essentially limited. Malebranche believes that God must act in accordance with general laws because if he were to intervene at every moment in the world, he would not act in accordance with his own nature. Moreover, the world would thereby cease to be intelligible to human beings. Occasionalism, consequently, guarantees the intelligible order of the universe.
Gottfried Wilhelm von Leibniz
Leibniz's philosophical system reflects an overarching commitment to the idea that there is a rational order to the universe that can be grasped by human minds. This commitment is manifest both in his more general epistemological and metaphysical views on display in works like the Monadology and in the philosophical theology contained in the Theodicy.
The foundation of Leibniz's philosophy is simple, soul-like substances, monads, which Leibniz believes are the only genuine substances in the universe. His argument rests on the claim that genuine substances must be simple, something he takes to be immediately evident to the human intellect. All other things—bodies, human beings, and animals—may be broken into their component parts; only minds are indivisible, and therefore only minds are substances.
Substantive metaphysical conclusions follow. Leibniz maintains that there may be no genuine causal interaction between substances, because genuine causal interaction would require that substances could be changed from without, thereby contravening their simplicity. Apparent changes are actually internal changes of substances. Because all changes are correlated with the states of all other monads, this "pre-established harmony" guarantees that apparent causal interactions will be grounded in actual changes in monads.
The idea of harmony lies at the heart of Leibniz's metaphysics. There is a preestablished harmony among the changes of substances; there is also a harmony between the order of nature and the order of grace, which ensures that the moral order will be realized. This point emerges clearly in Leibniz's claim that this is the best of all possible worlds. Here Leibniz seeks to defend God's goodness against the apparent visible evidence of all the evil in the world. According to Leibniz, this evil merely seems to tell against God's goodness. We know that God is a perfect being, and we know that a perfect being may act only in the best way. Consequently, the fact that God created this world reveals that it is the best of all possible worlds. The appearances that seem to tell against this are merely appearances, and we may therefore have confidence in the goodness and intelligibility of this world.
The Destiny of Rationalism
Kant's Critique of Pure Reason definitively limited the rationalists' pretensions to achieve knowledge of substantive truths by means of the intellect alone. Kant argues that knowledge is limited to the appearances presented to us by the senses; no extension of knowledge is possible to the "supersensible" or intelligible realm to which the rationalists, like Plato, purported to have access. Consequently, the rationalist belief in the capacity of the pure intellect to achieve knowledge of truths about the universe is revealed to be unfounded. Indeed, Kant's critique revealed that the rationalist commitment to pure intellect that can operate independently of the senses was untenable. Moreover, recent developments in science further reveal that the rationalist conception of the world as an intelligible order was overstated. Nevertheless, the rationalist commitment to the power of reason remained alive for Kant, particularly in his practical philosophy. Rationalism encouraged women to use their own reason in philosophy: Princess Elizabeth of Bohemia and Damaris Masham directly engaged Descartes and Leibniz, respectively, in correspondence; Margaret Cavendish and Anne Conway worked out a rationalist paradigm. Finally, from a historical standpoint most significantly, rationalism inspired Enlightenment thinkers to trust in human abilities without reliance on divine illumination.
See also Empiricism ; Epistemology ; Metaphysics .
Descartes, René. The Philosophical Writings of Descartes. 3 vols. Edited and translated by John Cottingham, Dugald Murdoch, Robert Stoothoff, and Anthony Kenny. Cambridge, U.K., and New York: Cambridge University Press, 1984–1991. Most complete English edition of Descartes's writings.
Kant, Immanuel. Critique of Pure Reason. Translated by Norman Kemp Smith. New York: St. Martin's, 1965. Classic, beautiful translation.
Leibniz, G. W. Philosophical Essays. Edited and translated by Roger Ariew and Daniel Garber. Indianapolis: Hackett, 1989. Good selection of Leibniz's writings, spanning his entire philosophical career.
——. Theodicy: Essays on the Goodness of God, the Freedom of Man, and the Origin of Evil. Edited by Austin Farrer. Translated by E. M. Huggard. La Salle, Ill.: Open Court, 1985. The most readily available English translation.
Malebranche, Nicolás. The Search after Truth. Edited and translated by Thomas Lennon and Robert Olscamp. Cambridge, U.K., and New York: Cambridge University Press, 1997. The most recent English translation.
——. Treatise on Nature and on Grace. Edited and translated by Patrick Riley. Oxford and New York: Oxford University Press, 1992. Fine edition; omits two of the Elucidations added by Malebranche.
Spinoza, Benedict de. The Collected Works of Spinoza, Vol. I. Edited and translated by Edwin Curley. Princeton, N.J.: Princeton University Press, 1985. Magisterial edition of Spinoza's early writings. Volume II is in preparation.
——. Theological-Political Treatise. 2nd ed. Translated by Samuel Shirley. Indianapolis: Hackett, 2001. Best available English edition.
Garrett, Don. The Cambridge Companion to Spinoza. Cambridge, U.K.: Cambridge University Press, 1989. Essays cover most aspects of Spinoza's work.
Hatfield, Gary. "The Cognitive Faculties." In The Cambridge History of Seventeenth-Century Philosophy, edited by Daniel Garber and Michael Ayers. Cambridge, U.K.: Cambridge University Press, 1998. Seminal article; treats both rationalists and empiricists from the standpoint of the cognitive faculties.
——. Routledge Philosophy Guidebook to Descartes and the Meditations. London: Routledge, 2002. Sustained interpretation of the Meditations as cognitive exercises; also considers alternative interpretations.
Nadler, Steven. The Cambridge Companion to Malebranche. Cambridge, U.K., and New York: Cambridge University Press, 2000. Essays cover most aspects of Malebranche's philosophical writings.
Rutherford, Donald. Leibniz and the Rational Order of Nature. Cambridge, U.K., and New York: Cambridge University Press, 1995. General interpretation of Leibniz's philosophy as motivated by the attempt to reveal the intelligible order of the universe.
Classical and Renaissance architectural treatises argued that architecture was a science with principles that could be understood on a rational basis. C18 and C19 theorists, notably J. -N. -L. Durand, Viollet-le-Duc, Semper, and others also argued for reasonable approaches to design derived from the culture of the European Enlightenment. Those arguing for C20 Rationalism did not have any one coherent theory, but made assumptions that architectural and urban problems could be solved primarily through an abandonment of Historicism and of movements such as the Arts-and-Crafts, Art Nouveau, and Expressionism (which they regarded as dead-ends), thus creating a tabula rasa on which to start again. They tended to be messianic in their desire for a new world, better architecture, Socialist structures, and a belief in the inherent rightness of what they were seeking, drawing on a Machine Aesthetic to achieve an appropriate image.
Advocates of Rationalism evolved certain principles by which their aims were to be met. First, architecture, industrial design, and planning could be used for social engineering and educational purposes, and so design had a moral meaning (a notion drawn partly from the writings of A. W. N. Pugin and Ruskin). Second, strict economy, cheap industrialized building methods, and a total absence of ornament were to be employed to achieve a minimum standard for everyone's habitation. Third, prefabrication, industrial technologies, and mass-production at all levels were to be used in the making of the new environment, but, even if traditional methods of construction were employed (bricks, after all, are mass-produced, standardized, prefabricated building-components), buildings should look machine-made in their pristine state (so brickwork was disguised by being covered with smooth render). Fourth, wholesale clearances, demolitions, and the destruction of existing urban fabric were deemed to be essential so that vast housing-estates could be erected. Lastly, form itself should be evolved for constructional, economic, functional, political, and social reasons, and so was not (in theory) subject to individual fancy (but in fact was largely determined by a few paradigms).
In practice, Rationalism encouraged an approved International style from which all historical and decorative elements were expunged, drawing on influences from e.g. Constructivism and de Stijl. Among key buildings were Gropius's Bauhaus, Dessau (1925–6), Le Corbusier's Maison Stein, Garches (1927), and houses at the Weissenhofsiedlung, Stuttgart (1927), while theoretical and unifying bases were provided by CIAM and certain writers, notably Giedion and Pevsner.
It is one of the curiosities of Rationalism that it flourished in Italy under Benito Mussolini's Fascist regime (1922–43), and in fact International Modernism was also called Rationalism by Gruppo 7. Terragni was perhaps the most distinguished Italian Rationalist, with his Fascist Party Headquarters, Como (1932–6). Gruppo 7 expanded to form the Movimento Italiano per l'Architettura Razionale (MIAR), inspired partly by Futurism. After the 1939–45 war Rationalism was adopted, virtually as the de rigueur style of Western Europe and America. Looked at objectively, it was just another style, drawing its motifs from a limited range of features approved in the 1920s, and owing very little to rationalism at all, but more to the desire for images thought to be appropriate for the times, and that, in any case, were usually only metaphors of mass-production, modernity, and industrialization.
Giedion (1967, 1969);
Gropius (1952, 1962, 1965);
Hilbersheimer (1925, 1927a);
Lampugnani (ed.) (1988);
Pevsner (1960, 1974a);
Placzek (ed.) and Robertson (1973);
T. Schumacher (1991);
Jane Turner (1996)
D. Watkin (1977)
Rationalism was a cultural movement from 1750 to 1820 that questioned social and intellectual traditions. Although rationalism did not reject tradition completely, it encouraged criticism of traditional laws, ideas, and social practices. Such criticism helped precipitate social and political change after 1750. One such change concerned the traditional privileges of aristocracy. Most rationalists were not aristocrats but were associated with the trading or commercial classes of the bourgeoisie. As such, rationalists often criticized aristocratic practices such as using birth or family lineage to determine a person's social position. In his Autobiography of 1771, the rationalist and American Revolutionary Benjamin Franklin boasted that his talent and merit, not his lineage, determined his social position in late-eighteenth-century Philadelphia. He suggested that talent and social mobility, not birth and traditional privilege, should characterize American society.
In addition to aristocratic practices, rationalists criticized intellectual traditions. Rationalists particularly opposed traditional religious ideas about human nature. The most influential of these ideas in 1800 were the orthodox Protestant ideas of Calvinism. Although originating with the sixteenth-century reformer John Calvin, Calvinism remained influential in America even after 1800. Calvinists held that human nature was inherently sinful and that human beings depended on God's grace for moral improvement. Rationalists scorned such ideas. They even replaced the traditional religious language of sin and grace, which suggested human dependence on God, with secular words like virtue and vice, which suggested human free will. One such rationalist was the American Founder Thomas Jefferson. Jefferson argued that human beings were not inherently sinful because they possessed "moral sense." This sense, he maintained, was part of human nature, enabling human beings to recognize virtue and pursue moral improvement without special grace or redemption from God.
For rationalists, such particular criticisms of aristocratic convention or traditional religion were not unrelated. They both derived from the rationalist principle that society was of human origin. Rationalists argued that the laws and institutions of society were not of divine origin or reflections of God's will, as many traditional writers had asserted. Instead, rationalists argued that society's laws and institutions were the product of human history, or the result of human decisions in history.
This emphasis on the human origins of society informed rational criticisms. By insisting that society's institutions and laws were the result of human decisions, and not part of an immutable order, rationalists challenged those institutions and laws as mere human creations. Rationalists thus challenged the legal privileges of aristocracy as merely the product of aristocratic decisions in political history. The aristocracy, they charged, made the laws of aristocratic privilege. Rationalists similarly criticized the clergy. They viewed the clergy as possessing power and prestige because clerical leaders had influenced the political decisions of history. One rationalist who expressed these critical views was the American Revolutionary John Adams. In 1765 Adams published A Dissertation on the Canon and Feudal Law, in which he condemned the history of aristocratic and clerical power as a history of "civil and ecclesiastical tyranny."
The rational view of society also promoted confidence in reform. By describing institutions and laws as the product of past decisions, rationalists expressed confidence in the human ability to change those decisions and reform their society. Such confidence was evident in the writings of Thomas Paine. In Common Sense, published in January 1776, Paine characterized the long-established institution of monarchy as merely a form of tyranny. He thus sought to convince Americans to reform their politics not simply by declaring independence, which they did in July 1776, but also by creating a new kind of government based on rights rather than kings.
Rationalists expressed a confidence in human ability both in their religion and their politics. By the early nineteenth century, religious rationalism developed into Unitarianism. Unitarians were optimistic about human nature and encouraged individuals to use reason and moral sense rather than traditional doctrines as guides to individual and social life. Unitarians thus sought to replace the traditional Christian doctrine of the Trinity—God as Father, Son, and Holy Spirit—with a "united" or indivisible notion of God, which they viewed as more rational. Unitarianism was particularly influential among the merchant classes of Boston. The leading Boston Unitarian was William Ellery Channing (1780–1842). In 1819 Channing published Unitarian Christianity, in which he expressed many essential features of rationalism. He emphasized the human ability to use the free and rational faculties of human nature for moral self-improvement and social reform.
Sanford, Charles B. The Religious Life of Thomas Jefferson. Charlottesville: University Press of Virginia, 1984.
Zuckert, Michael P. The Natural Rights Republic: Studies in the Foundation of the American Political Tradition. Notre Dame, Ind.: University of Notre Dame Press, 1996.
Christopher S. Grenda
ra·tion·al·ism / ˈrashənlˌizəm; ˈrashnəˌlizəm/ • n. a belief or theory that opinions and actions should be based on reason and knowledge rather than on religious belief or emotional response: scientific rationalism. ∎ Philos. the theory that reason rather than experience is the foundation of certainty in knowledge. ∎ Theol. the practice of treating reason as the ultimate authority in religion. DERIVATIVES: ra·tion·al·ist n. ra·tion·al·is·tic / ˌrashənlˈistik; ˌrashnəˈlistik/ adj. ra·tion·al·is·ti·cal·ly / ˌrashənlˈistik(ə)lē; ˌrashnəˈlistik(ə)lē/ adv.