Kant’s Critique of Pure Reason: Knowledge, Metaphysics, and the Subject
The proposed text is an excerpt from the introduction of Immanuel Kant’s fundamental work, Critique of Pure Reason, where he developed his theory of knowledge, which has become foundational to philosophy. The core problem addressed in this work, and clearly reflected in the text, concerns the possibilities and limitations of knowledge based on our cognitive faculties. In the introduction, Kant explores the viability of metaphysics as a science, comparing it to mathematics and physics.
According to Kant, metaphysics lacks the scientific rigor of mathematics and physics because it continuously debates the same issues raised by Plato and Aristotle. While scientists generally agree on their core themes and conclusions, metaphysics is characterized by persistent disagreement. Therefore, the central question is whether metaphysics can be a science: if so, it must progress beyond its current state; if not, we should abandon the illusion of constructing metaphysical systems that claim scientific validity.
Initially, Kant notes that all attempts to ground knowledge solely on experience have failed. This failure, according to both empiricists and rationalists, stems from focusing on the object of knowledge (ideas for rationalists, perceptions for empiricists) rather than the subject (the knower).
Inspired by Copernicus, Kant inverts this approach, shifting attention to the knowing subject. The subject becomes the organizer of cognitive experience, with objects depending on and adapting to the mind’s structure. The subject is the active element in knowledge acquisition, shaping the object by integrating it into their cognitive system.
Through this ‘Copernican revolution,’ Kant argues that the intuition of objects is not solely empirical but is structured by the subject’s intuitive capacity. However, for these intuitions to become knowledge, they must refer to an object. Thus, experience requires a priori concepts (space and time) that govern all objects of experience. Since space and time are properties of the subject, not the object, knowledge is inherently subjective, structured by these a priori forms.
Contextualization
Kant’s life (1724-1804) was set in Prussia during the Age of Enlightenment, a movement he epitomized. The Enlightenment’s emphasis on reason was not an endorsement of rationalism alone but transcended the differences between rationalism and empiricism. The focus shifted from the origin of knowledge to reason’s capacity to process it.
The diverse interpretations of reason necessitated clarification, primarily through the examination of reason itself. The problem was to understand the possibilities of knowledge given our cognitive powers. Kant found it astonishing that philosophers sought to know reality and humanity without first questioning the possibility of such knowledge. He argued that there were both historical and philosophical reasons to examine reason. Historical reasons arose from the antagonism between different philosophical interpretations (dogmatic rationalism, positivism, irrationalism, etc.). Philosophical reasons stemmed from how empiricists and rationalists conceived of knowledge, focusing on the object rather than the knowing subject.
Kant began as a rationalist philosopher, believing that understanding produces concepts not derived from experience. However, influenced by Hume, he shifted away from rationalism, concluding that knowledge cannot extend beyond experience. While he acknowledged that understanding has concepts originating from experience, their application is limited to the realm of experience. Kant disagreed with the empiricist thesis that all concepts come from experience; instead, he argued that while concepts originate in experience, their application is confined to it.
The text is a fragment of the Critique of Pure Reason, where Kant outlines a path to factual knowledge and, as far as possible, knowledge of objects. In the introduction, Kant addresses the possibility of metaphysics as a science. This requires examining the conditions (empirical and a priori) that make metaphysics possible and determining if it can meet these conditions. After identifying these conditions, Kant investigates the types of judgments used in science to understand the transcendental conditions that make them possible. Kantian judgments are categorized as analytic, synthetic a priori, and synthetic a posteriori. Kant argued for the existence of synthetic a priori judgments, which are expansive yet universal and necessary. The fundamental principles of science are of this type. Kant then explores how such judgments are possible in mathematics and physics and whether they are possible in metaphysics. In the Transcendental Aesthetic, he studies sensibility and synthetic a priori judgments in mathematics. Kant identifies two types of sensibility: outer sense (spatial representation of external objects) and inner sense (temporal intuition). Therefore, as reflected in the text, sensible knowledge requires space and time as necessary conditions.
Synthetic a priori judgments are possible in mathematics through space and time. Since space and time are properties of the subject, not the object, knowledge is inherently subjective, structured by these a priori forms. This initial knowledge comprises two components: the material element (sense impressions) and the formal element (a priori forms structuring reality). The result is the phenomenon, the sensory impression given through space and time (the noumenon is the thing-in-itself, which is unknowable).
In the Transcendental Analytic, Kant studies understanding and synthetic a priori judgments in physics. The intellect’s function is to understand what is perceived. Understanding phenomena involves forming concepts, an activity always carried out through judgment. Thus, understanding can be seen as the power of judgment. The a priori forms of understanding, which make comprehension possible, are concepts, either empirical or a priori (pure categories). Kant identifies twelve categories of understanding (corresponding to possible forms of judgments), based on quantity, quality, relation, and modality. The intellect can only think about phenomena if these categories are applicable, but the categories are only validly applied to realities within experience. Synthetic a priori judgments are the fundamental principles underlying physics.
In the Transcendental Dialectic, Kant examines reason and the possibility of metaphysics as a science. Reason’s function is to unify knowledge through ideas, reducing the variety of objects to the fewest possible principles. The principles of reason are pure, unconditioned ideas, not judgments but a priori concepts (pure concepts of reason or transcendental ideas) that unify phenomena. The transcendental ideas of pure reason are the Soul (unifying inner experience), the World (unifying external experience), and God (unifying both).
Metaphysics studies the universe, the Soul, and God using reason. Soul, world, and God are a priori forms of pure reason; we have no sense impressions of them, so we cannot form synthetic judgments (sense impressions without a priori forms are chaotic, and a priori forms are empty without sense impressions). Metaphysics as a science is impossible, yet it is an inevitable and natural tendency, as reason seeks the unconditioned, asking questions and formulating answers about God, the Soul, and the World. The ideas of pure reason have a regulative use in investigating nature: they set limits and drive the expansion of research into new experiences and greater connections between them.