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Fries, Jakob Friedrich

Fries, Jakob Friedrich

(b. Barby, Germany, 23 August 1773; d. Jena, Germany, 10 August 1843)

philosophy, physics, mathematics.

Fries was educated in Niesky at the Moravian Academy of the United Brethren of Herrenhut. This upbringing had a lasting influence upon him, even though he early freed himself from the religious dogmas learned in his theological studies there. In 1795 Fries went to Leipzig to study philosophy and in 1797 he transferred to Jena to study with Fichte. By 1798 he had published five essays on the relation of metaphysics to psychology. Having completed his course at Jena, he spent a year as a private tutor in Switzerland. At the same time he worked to finish his thesis, “De intuite intellectuali,” with which he qualified as docent at Jena in 1801.

In 1805 Fries was called to become an assistant professor of philosophy and elementary mathematics at Heidelberg. In 1816 he returned to Jena as full professor of theoretical philosophy. He was suspended because of political pressures following his participation in the Wartburgfest, a demonstration by liberal students in October 1817. Fries did not obtain permission to teach again at Jena until 1824, when he received a professorship of physics and mathematics. In 1825 he became professor of philosophy, a post he held for the rest of his life.

Fries considered himself Kant’s most loyal disciple. He believed that Kant had finished the philosopher’s task for all time and that only individual elements of his doctrine were susceptible to correction. Despite this belief Fries himself decisively altered the Kantian formulation by psychologizing Kant’s transcendental idealism in his major book, Neue oder anthropologische Kritik der Vernunft (Heidelberg, 1807). He was opposed to all contemporary speculative systems and considered the Romantic interpretation of nature good only for aesthetics. In opposition to Schelling and his school, he went back to the attitude of critical Kantianism that held Naturphilosophie to be the philosophy of exact sciences (see, for example, his Die mathematische Naturphilosophie [Heidelberg, 1822]).

Fries also spoke for contemporary positive scientific research, for which he gained authority from his works on physiological optics and the theory of probabilities, as well as from his textbook on experimental physics. With Kant he asserted the possibility of an a priori natural science, designed to show how the categories are applicable to experience as determinations of time through universal mathematical schema and how a system of universal laws of nature arises from this union. This system encompasses the theory of pure motion, which unites Newton’s mathematical approach with Kantian philosophy. (Fries’s interpretation of Newton was strongly influenced by the commentary of Le Seur and Jacquier to their four-volume 1739 edition of the Principia, which contains the development of those mathematical propositions that Fries presented in detail in his own Die mathematische Naturphilosophie).

Fries’s system almost yields the philosophy of applied mathematics, although there remains the field of derivable statements a priori. Among them Fries considers the Newtonian axioms to be foremost. On the other hand, attraction and its lawfulness cannot be deduced a priori. While Fries took over Kant’s classification of natural knowledge into the four disciplines of phoronomy, dynamics, mechanics, and phenomenology, he added two new ones that he designated stochiology and morphology. Stochiology treats dynamics from a comprehensive viewpoint and attempts to establish a dynamic explanation of heat and light, as well as electrical and chemical phenomena.

Whereas Fries, like Kant, explained matter dynamically—and indeed he was much more sharply opposed to the atomists than was kant—he deviated from him considerably with regard to dynamics itself. This is illustrated particularly by his rejection of apriorism in the concrete determination of the degree of force with which masses act upon each other. In further opposition to Kant, Fries posited four types of fundamental force in the constitution of matter: attractive and repulsive forces acting at a distance as well as attractive and repulsive contact forces. For the first two types of force the simplest mode of action is given by their proportionality to 1/v2, for the latter two, by the proportionality.

Fries took a final important step beyond Kant in the introduction of the organic into his system of nature through the supposition of natural instincts. This doctrine of the instincts stated that along with the determination of the forms of interaction, the law of the counteraction of the fundamental forces (that is, the behavior of the moved mass in space) must also be considered. According to Fries, the succession of appearances is caused by such instincts, which display complete forms of reciprocal action. They alone, rather than particular materials and forces, provide the explanation of physical phenomena and processes.

Physical processes may be divided into four types: gravitational (heavy masses acting at a distance); chemical (heavy masses in admixtures and dissociations with contact action); phlogistic (in which the counteraction is determined by caloric); and morphotic (in which the counteraction is determined primarily by the rigidity of the moving forces). The instincts on which these processes are based may be further divided into two classes—instincts of mechanisms and instincts of organisms. In Fries’s view, all processes that are freely determined by uniformly accelerating attractive forces must be attributed to organic instincts; and all processes that are determined by attraction of bodies in contact without acceleration, and are thus reaching a state of rest in reestablished equilibrium, must be attributed to mechanical instincts.

Planetary orbits and pendulum motion may, if air resistance and friction are ignored, serve as examples of the action of organic instincts. Organizing instincts here predominate over mechanical ones, since otherwise the world, beginning in chaos, would attain motionless equilibrium in finite time. The prevalence of organizing instincts is necessary to the closed system of periodic recurrence of events required for a world without beginning and without end. Lesser cycles of events are the only ones that can be altered from the outside alone. If one supposes these comprised in greater cycles of events in which, again, the organic force predominates, and then supposes these greater cycles included in still greater ones, and so on, a lack of exact periodicity in the whole is understandable.

The distinction between organic and mechanical instincts makes it possible to distinguish between organic and inorganic nature. An inorganic (dead) body, or mechanical formation, is any that is formed according, to the law of equilibrium; a living body obeys the law of self-preservation of its motion—this principle of self-preservation is the corporeal soul. The corporeal soul itself exhibits only the form of the interaction of the corporeal parts. This definition reflects Kant’s determination of the organism as the causalitas mutua of its parts.

According to Fries’s speculative natural history, the cosmos is constructed out of three elements—earth, water, and air—according to weight. In the solid core of the earth the forces have long maintained themselves in equilibrium. Above the earth, in the water and air, the equilibrium is preserved by the action of sunlight, the daily and yearly motion of the earth, and the electrical reaction of the atmosphere to the earth, and the electrical reaction of the atmosphere to daily and annual heating and cooling cycles. In addition, the vigor of the life-movements and the circulation of life as the basic vital principle also depend upon thermal-electrical relationships. “All morphotic processes are dominated by the formative instincts [Bildungstrieben], and specifically the mineral and the two organic instincts,”Fries wrote.

The laws of crystallization display the true morphotic principle. Without denying the differences between crystal and organism (including the difference in mode of growth, namely apposition as opposed to intussusception), Fries maintained that these laws are crucial to an understanding of organic form. Indeed, organic formation to the extent that it represents a higher, correspondingly altered process, is to be understood only on the basis of crystallization. Fries called for a theory of free crystallization to expedite a theory of organic formation: he thereby thought to explain a self-maintaining organic process by means of the circuit law of the voltaic cell. It is necessary to this hypothesis, however, that the electrical currents that arise in the play of chemical combinations and dissociations flow in such a way as to transform the oxides emerging from contact with the conductor of the second class, so that the material of this conductor be replaced. Fries could thus ask if a plant might be a self-maintaining open voltaic chain whose root acts as a negative conductor while the opposite pole puts forth leaves and flowers, or if an animal might be a self-maintaining closed voltaic chain that therefore also possesses its own inherent magnetism.

Fries devised a diagram

to represent the bases of all empirical theories of formation and dissolution in the three natural kingdoms. His representation combined the two polar principles of electrical and material opposition. In this system electrical opposition emerged as the principle of all animation through the activity of sunlight on water, while the differences between chemical materials, represented by the original opposition of carbon and nitrogen, is the principle of all production of form. The effect of these two original polarities on each other allowed the reconciliation of the three natural instincts posited by Fries. Specifically, the water-light polarity reconciled the mechanical-mineral instinct; the open circuit between water, carbon, and nitrogen, the vegetative one; and the closed circuit between nitrogen, light, carbon, and water (which encompasses the whole of nature), the animal instinct.

Fries’s doctrine of nature thus can be understood only in connection with romantic Naturphilosphie, in which the idea of polarity and the importance of magnetism and galvanism were employed to account for far more than just physical events. Fries’s doctrine of nature, however, employed the natural science available at the time in a serious attempt to overcome Kant’s vitalism, which even a Newton of the grass-blades would not accept. Indeed, his speculations in natural philosophy were actually fruitful for the development of modern biology through the work of his student Matthias Schleiden, who sought to put into practice the idea of the reduction of the organic to crystallization processes and thereby became the founder of modern cytology.


I. Original Works. Fries’s principal work is Neue oder anthropologische Kritik der Vernunft, 3 vols. (Heidelberg, 1807; 2nd ed. 1828–1831). His other scientific works include Entwurf eiones Systems der theoretischen Physik (1813); Die mathematische Naturphilosophie nach philosophischer Methode bearbitet (Heidelberg, 1822); and versuch einser Kritik der Prinzipien der Wahrscheinnlichkeitsrechnung (Brunswick, 1842). A detailed bibliography of his books and essays is contained in the biography written by his son-in-law Henke, pp. 379 ff.

A 26-vol. ed. of Fries’s collected works, ed. and with intro. and index by Geri Koenig and Lutz Geldsetzer, is in publication (Aalen, 1969– ).

II. Secondary Liteature. Works about Fries include T. Elsenhaus, Fries und Kant. Ein Beitrag Zur systematischen Grundlegung der Erkenntnistheorie, 2 vols. (Giessen, 1906); kuno Fischer, Die beiden Kantischen Schulen in Jena, Akademische Reden no. 2 (Stuttgart, 1862); M. Hasselblatt, J. Fr. Fries, Seine Philosophic und seine Personenlichkeit (Munich, 1922); E. L. T. Henke, J. Fr. Fries; Aus seinem handschriftlichen Nachlass dargestellt (Leipzig, 1867); J. G. Meusel, in Das gelehrte Teuschland oder Lexicon der jetzt lebenden teuschen Schriftsteller, vol. II, and also in Nerolog der Deutschen jgg. (1823–1853), Conversationslexicon, vol. X–A (Leipzig, 1851–1855); and C. Siegel, “Fries, Fortbildung der Kantischen Naturphilosophie,” in Geschichte der deutschen Naturphilosophie, (Leipzig, 1913), pp. 119–130.

H. M. Nobis

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"Fries, Jakob Friedrich." Complete Dictionary of Scientific Biography. . 27 Apr. 2017 <>.

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Jakob Friedrich Fries

Jakob Friedrich Fries

The German philosopher Jakob Friedrich Fries (1773-1843), interested in the phenomenon of the mind, advanced psychological philosophy in the direction of psychological empiricism.

Jakob Friedrich Fries, born in Barby, Saxony, on Aug. 23, 1773, studied at Leipzig and Jena. He became dozent at Jena in 1801, professor of philosophy and elementary mathematics at Heidelberg in 1805, and professor of philosophy in 1814. In 1816 Fries accepted the chair of theoretical philosophy at Jena.

Fries was one of the links in a chain which gradually transformed psychology from metaphysics to empiricism, from philosophy to science. A disciple of Immanuel Kant, he did not agree with Kant on all points but sought rather to reshape and elaborate the principles of critical philosophy. He was thus considered by some an opponent of Kant. Perhaps "semi-Kantian" describes him best, for the system which Fries developed was really midway between that of Kant and that of the "commonsense" school.

In his chief work, Neue oder psychologische Kritik der Vernunft (1807; New Critique of Reason), Fries tried to combine the teaching of Kant with elements from Friedrich Heinrich Jacobi's philosophy of faith, basing critical philosophy on psychology and substituting self-observation for the transcendental method. Fries maintained that only that which is sense-perceived can be known and that the principles of reason are immediately known in consciousness. Kant had sought to prove the principles of reason a priori. Fries, however, contended that human beings cannot know the supersensible, or things-in-themselves. They are objects of faith which satisfy the demands of the heart.

Like Kant, Fries discussed psychological facts under the heading of anthropology, considering them in the light of the customs of primitive peoples, and empirically thinking of the mental processes themselves as being the data that psychology had best study. The modern reader can possibly make more relevant sense of Fries by substituting "phenomenological" for Fries's "anthropological."

In 1821 Fries published the Handbook of Psychical Anthropology, in which he divided anthropology into mental and physical aspects. Under mental anthropology he studied the actual processes by which one perceives, remembers, and thinks. The mental processes, although depending upon a pure ego or self, are never known except through their effects. Similarly, the ego or self cannot be appreciated for itself but is known only through its effects. Under physical anthropology Fries discussed the relationship between brain and mind. He distinguished three main faculties: knowledge, inner disposition (Gemüth) or feeling, and activity or will. He regarded each of these faculties as incorporated in or subordinated to the unitary self.

Further Reading

Virtually all of the important sources on Fries are in German. One of the few works in translation is Rudolf Otto, The Philosophy of Religion Based on Kant and Fries (1921; trans. 1931). For background material see George Sidney Brett, Brett's History of Psychology, edited and abridged by R. S. Peters (1953). □

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