Kant’s Critique of Pure Reason: Limits of Metaphysics as Science
Kant’s Critique of Pure Reason: Exploring the Limits of Knowledge
The Copernican Revolution in Epistemology
The fundamental problem of the Critique of Pure Reason is to determine the limits of human knowledge. Kant’s epistemological approach centers the subject as an active constructor of concepts and judgments, expressing genuine scientific knowledge. This has been called the “Copernican Revolution” in philosophy.
The Truth of Scientific Statements and the Role of Metaphysics
Kant doesn’t question the truth of scientific statements. His critique takes scientific truth as a given, aiming to elucidate whether and how metaphysical judgments can achieve the same degree of truth as scientific propositions. A central objective of the Critique of Pure Reason is to determine if metaphysics can be considered a science.
Universality and Necessity as Criteria for True Knowledge
To answer this question, Kant first defines the conditions for true scientific statements and then defines the concept of metaphysics, considering previous philosophical models. For human knowledge to be considered scientific, it must meet the criteria of universality and necessity. “False knowledge” fails to fulfill these characteristics, representing an illegitimate operation of reason.
Analyzing Judgments: A Priori vs. A Posteriori, Analytic vs. Synthetic
Given that universality and necessity characterize true knowledge, Kant explores how these characteristics are expressed in judgments. All knowledge is expressed in judgments, which link subjects with predicates. Judgments can be true or false. Kant classifies judgments into two categories: a priori and a posteriori, and also into analytic and synthetic.
- Analytic judgments: The predicate is included in the subject (e.g., relations between ideas). Analyzing the subject reveals the predicate without needing experience.
- Synthetic judgments: These broaden the field of experience but alone cannot provide the necessity and universality required for scientific truth. According to Kant, this knowledge relies on empirical generalizations and needs further augmentation to be considered scientific.
- A posteriori judgments: Their truth is established through experience, meaning they can be corroborated or falsified by it (e.g., “The table is green”).
- A priori judgments: Their truth is independent of experience, existing prior to and independent of it. These judgments express pure reason—the innate capacities of reason before any empirical operation.
Synthetic A Priori Judgments: The Foundation of Scientific Knowledge
Kant argues for the existence of synthetic a priori judgments, which form the basis of scientific knowledge. These judgments provide necessary and universal knowledge while also being connected to experience. Mathematics and theoretical physics exemplify this type of judgment.
Reason’s Construction of Judgments: Matter and Form
Kant explains that every judgment comprises matter and form. Matter is the empirical content, while form is how reason organizes and structures the judgment. In sensibility, impressions are the matter, and space and time are the forms. The synthesis of intuitions creates phenomena. In understanding, phenomena are the matter, and categories are the form. The synthesis of matter and form (experience and a priori categories) produces concepts and judgments. Intuitions without concepts are blind, and concepts without intuitions are empty. Sensibility creates phenomena, and understanding synthesizes them with categories, leading to concepts.
The Impossibility of Metaphysics as a Science
Synthetic a priori judgments cannot exist in metaphysics because the constitution of metaphysical concepts doesn’t consider experience. There’s no experience of the soul, freedom, or God, so judgments containing these concepts cannot extend our knowledge of them. In a judgment like “The soul is immortal,” the concept of “soul” doesn’t refer to sensory data but to a supposed essence. Metaphysics operates on alleged underlying realities (noumena), which are beyond our sensible experience. Metaphysical judgments mimic scientific judgments but are ultimately pretense.
The Role of Metaphysics in Practical Reason
Metaphysical judgments have no place in pure reason, but due to reason’s tendency to produce them (metaphysica naturalis), they cannot be eliminated. Kant’s solution is to relocate them to practical reason, where they serve a regulatory function, guiding our moral lives.
Conclusion: The Enduring Legacy of Kant’s Critique
Kant concludes that metaphysics as a science is impossible because it transcends the limits of possible knowledge. However, due to reason’s structure, we inevitably encounter metaphysics. Kant proposes a regulative use of pure reason’s ideas as guides for knowledge and scientific research. Kant’s philosophy has had a profound and lasting impact. His work influenced 19th-century philosophy, his theories on knowledge structures were validated by 20th-century biology, and despite his critique, metaphysics persists. His postulates of practical reason influenced Romantic and Hegelian idealism, and his concept of man as an end in himself impacted Marx’s political theories.