The Historical Development of Philosophy

New Philosophy

Kant's Critical Philosophy

In the preceding period, two distinct directions developed: rationalism and empiricism. Kant (1724—1804), in his critical philosophy, seeks to reconcile their opposition, endeavoring to establish appropriate boundaries for both sources of knowledge—thought and experience—and to impartially evaluate the significance of their contributions to any genuine understanding. To this end, he embarks on an investigation of the functions of knowledge, a task he believes has been overlooked by both rationalists and empiricists of earlier times; indeed, the mutual opposition arises from differing dogmatic presuppositions. Since the resolution of the problem of knowledge impacts our approach to other philosophical inquiries—metaphysical, ethical, and religious—Kant considers critical examination of our capacity for knowledge as a task that can ultimately unlock satisfactory resolutions to both practical and theoretical problems.

Kant employs a general criterion regarding the origin of the elements of knowledge: anything claiming general significance and necessity must derive from a priori functions of knowledge; conversely, anything characterized by contingency is deemed empirically given. Thus, in contrast to the preceding rationalism, which reduces all a priori knowledge to concepts, Kant distinguishes between two kinds of forms of knowledge inherent to us: forms of intuition—space and time—and forms of concepts or categories, such as reality, negation, substance, and causality, which find continuous application in our understanding, although they cannot be derived from the empirical content of perceptions. They possess the traits of general significance and necessity, which are never characteristic of the empirical, being contingent by nature. In contrast, the solely empirical and contingent aspect of perceptions is the content of sensation. For any actual knowledge, both components are required: the empirical material given in sensation and the form provided by the universal forms of intuition and concepts, with the intuitive form always presented in some order of time. For Kant, time is not merely, like space, a form of intuition that organizes external impressions but also a form of "inner sense" that accompanies our own thought; hence, all representations of external senses must be encompassed within it. Thus, time serves as a universal framework for the categories and the general laws resting upon them. For example, the fundamental law of the permanence of substance necessitates the contemplation of temporal duration; the law of the alternation of cause and effect within causality requires the perception of temporal succession, and so forth.

From this analysis of the functions of knowledge, it follows that, on one hand, all empirical knowledge is both empirical and rational, as the given material of sensations is always complemented by a priori forms of intuition and concepts that render this content genuine experience; however, on the other hand, no knowledge in the form of intuition or concept can exist without the empirical content of sensation. Thus, all our actual knowledge is constrained by experience. Kant's critique of knowledge resolves the dispute between rationalism and empiricism by acknowledging the former's right to recognize the involvement of rational elements in all knowledge while confining the latter to experience. By eliminating this fundamental opposition, which had sown discord in the philosophy of the preceding period, the other oppositions that characterized various philosophical worldviews also fall away, primarily the opposition between subjectivism and objectivism, between universalism and individualism, and between pantheism and theism. The overall position Kant occupies in the historical development of modern philosophy can therefore be more clearly elucidated through his relation to preceding directions than through his own systematic exposition of his system, which often suffers from an artificial schematism of concepts.

Subjective idealism, as propounded by Berkeley, reduces all knowledge to subjective representation, while materialism acknowledges reality only in objects existing outside of us; both, according to the tenets of critical philosophy, are erroneous. Subjective idealism is insufficient because, while it correctly asserts that all knowledge is a subjective process, the fact that the content of sensation is given to us rather than produced by our thought points to the "thing-in-itself" as the real condition of the objectively given object. Conversely, materialism not only overlooks the role of a priori functions of knowledge in every individual understanding, even in immediate sensory experience, but also denies the inherent nature of our reason, which, due to its innate inclination to transition from the conditioned to its conditions, cannot accept the ultimate condition of all thought and being as the empirically given reality. Rather, it inevitably leads to the idea of a higher condition that lies beyond the given reality, hence a transcendental condition. By recognizing the object as given to our knowledge, materialism thus disregards the fact that due to the nature of the functions of knowledge, we can only be presented with phenomena—i.e., the content of knowledge formed through our cognitive functions. Instead of phenomena, materialism dogmatically substitutes "things-in-themselves," which can never become objects of knowledge. Consequently, for materialism, the recognition of a super-sensory world as the ultimate necessary foundation of the sensory world becomes superfluous.

Considering both perspectives—the view of bare subjectivism and pure objectivism—as equally flawed due to their one-sidedness, critical philosophy resolves the dispute between universalism and individualism by asserting that both are indeed correct, albeit in different domains. Every act of knowledge originates from the "I": thus, individualism rightly perceives the functions of knowledge as the activity of individual self-consciousness. Conversely, every action pertains to the universal; hence, the law under which will operates cannot be individual but must instead be a universal law. In truth, Kant's moral law possesses this characteristic, existing in our moral conscience as a principle independent of individual inclinations and considerations of utility. However, since the universal transcends individual consciousness, the non-empirical nature of the moral law is revealed, alongside the transcendent, non-empirically conditioned character of the will, which acts under the postulate of its freedom.

Ultimately, the dispute between pantheism and theism is, from a critical standpoint, fundamentally irresolvable. While the moral law signifies the non-empirical nature of humanity and presents itself as an unconditional law, independent of empirical conditions, it simultaneously indicates a supersensible origin and thereby refutes atheism; however, it does not permit a more precise definition of the concept of God. Nevertheless, within Kant's exploration of religious philosophy, a tendency towards the idea of a personal originator of the moral law emerges, thus leaning towards theism. In any case, Kant had this in mind in his moral proof of the existence of God and in his arguments for the immortality of the soul. The moral law, demanding a legislator, must equally postulate, as an absolute command, the unconditional fulfillment of its edicts, thus necessitating moral perfection. Yet, since this perfection is unattainable in earthly life due to human sensual inclinations, the necessary assumption of the moral law's feasibility requires acknowledgment of immortality.

Consequently, the result of Kant’s philosophy is the delineation of the realms of knowledge and faith, which parallels the division between the two fundamental capacities of the human spirit: knowledge and will. It follows that our knowledge must inevitably prove inadequate if one attempts to derive judgments about the essence of the soul, the totality of the world, and the beginning of causality in nature, or, finally, the existence of God from pure concepts. Thus, rational psychology, cosmology, and theology of the preceding era—the era of dogmatic philosophy—are merely illusory sciences that either entangle themselves in false conclusions (psychology), or in contradictions, antinomies (cosmology), or rest upon an ontological confusion of simple concepts with reality (theology). In all these transcendental ideas, what is at stake are practical postulates: they thus pertain to the realm of will rather than knowledge, and the postulate from which all others flow, in a certain sense, is the postulate of free will, which exclusively relates to the will as a supersensory capacity. Thus, the first of the two mentioned functions—knowledge—belongs to the sensory nature of humanity, while the second—will—pertains to the supersensory, the "intelligible." Consequently, the will as such is not subject to natural causality; however, external volitional actions fall within the realm of natural phenomena, which are interlinked in causal dependency.

For this reason, knowledge branches into a multitude of sensory and intellectual functions, forms of intuition and concepts, to which correspond, in turn, a variety of universal a priori laws of knowledge. The will, however, indicating the unity of the supersensory nature of humanity, constitutes a singular capacity, possessing only one a priori, purely formal fundamental law of action: the moral categorical imperative, by which one should "act in such a way that the principle of one’s action could be made a universal law." Nevertheless, since the supersensory nature of humanity must be regarded as the ultimate foundation of sensory nature, the fundamental law of the will, according to Kant, thus holds an unconditional primacy over all fundamental laws of knowledge.