Kant’s Critique: Limits of Rational Knowledge and Metaphysics
Kant’s Critique of Pure Reason
Kant devoted his major work, Critique of Pure Reason, to resolving the question of the limits of rational knowledge of reality. The problem was that metaphysics did not progress, unlike other sciences. The importance of these issues prevents us from dismissing its study due to this initial difficulty. The strategy: identify the conditions that enable mathematics and physics to be sciences, and then check whether metaphysics meets those conditions.
1 – Classification of Judgments
Kant believed that a correct classification of judgments must meet two different criteria:
- The relationship between subject and predicate:
- Analytical Judgments: The information given by the predicate is already contained in the subject.
- Synthetic Judgments: The predicate provides new information about the subject.
- The source of the judgment’s truth:
- Judgments a priori: Their truth can be known without conducting empirical tests.
- Judgments a posteriori: Their truth can only be established after an experimental test.
Combining the two classifications:
- Analytical a priori Judgments: Universal and necessary, but do not extend our knowledge.
- Synthetic a priori Judgments: Universal, necessary, and expand our knowledge.
- Synthetic a posteriori Judgments: Extend our knowledge, but are neither universal nor necessary.
2 – The Transcendental Aesthetic
When a sensation is captured by the subject, it becomes an intuition. The object captured by intuition is called a phenomenon. A phenomenon is composed of:
- Subject Matter: The content of the sensation, given a posteriori.
- Form: The way the subject matter is captured, which we have a priori. This form of sensible intuitions consists of two elements, space and time, which are a priori forms of our sensibility.
Geometry and arithmetic are the cornerstones of mathematics. Thus, the features we have discovered in space and time are the foundation of a priori synthetic judgments in mathematics.
3 – The Transcendental Analytic
The Transcendental Analytic is concerned with understanding. It builds judgments and forms chains of reasoning through concepts. Kant contemplates the existence of empirical and pure concepts:
- Empirical Concepts: Created by the understanding from what is captured in sensory experience.
- Pure Concepts (Categories): Exist in the understanding prior to any experience. There are as many categories as there are types of judgment. They are the foundation of synthetic a priori knowledge of physics because all experience must conform to the diagram provided by the categories.
4 – The Copernican Revolution: Phenomena and Noumena
What is known are phenomena, and the noumenon is, by definition, unknowable. Knowledge of mathematics and physics involves phenomena. No one knows reality as it is. The human being is forced to change reality so that it can be known. Kant suggested that the object adapts to the knowledge of the subject, so it can be known by it. He called this the Copernican Revolution, for the change of understanding that it made.
5 – The Transcendental Dialectic
This studies understanding as the faculty of forming judgments and chaining reasoning. Human reasoning uses syllogisms. A syllogism is a set of statements. From this set of statements, one of them, called the conclusion, is obtained from the others, called premises. If the premises are true, the conclusion will be true.
Conclusion: The Limits of Epistemology
Metaphysics acts on noumenal entities, obtaining a priori synthetic judgments by applying the categories to the ideas of God, soul, and world. But as sensuous intuition does not possess any of these three ideas, it does not produce true knowledge. Metaphysics cannot become a science because its objects of study are beyond the limits of human knowledge.