Kantian Epistemology in the Critique of Pure Reason

The Structure of the Critique of Pure Reason

The Critique of Pure Reason is divided into three parts: transcendental aesthetics, transcendental analytic, and transcendental dialectic.

Transcendental Aesthetics: Space and Time

In Kant's transcendental aesthetics, he examines the possibility of sensitive knowledge (asking: is mathematics possible as a science?). He establishes the a priori forms of sensibility, which are pure intuitions known as space and time.

By sensibility, we mean the power of humans to be affected by impressions. We receive these impressions in a disorderly manner; it is by filtering them through space and time that we can sort (synthesize) and, therefore, know them. In this way, sensitive knowledge occurs when we know through impressions, which are the material, and the a priori forms of sensibility (space and time).

That is why Kant draws a boundary between what we can know objectively and what we cannot. That is, the boundary between science and metaphysical speculation is experience.

Transcendental Analytic: Judgments and Categories

The transcendental analytic questions the possibility of understanding and intellectual knowledge (asking: is physics possible as a science?).

In this section, there are two types of judgments:

• Analytical judgments: The predicate is contained in the subject and does not provide new information.
• Synthetic judgments: The predicate is not contained in the subject and, therefore, provides information about the world.

These can also be divided into two groups: a posteriori, whose validity depends on experience, and a priori (independent of experience), which are both informative and compelling. Kant based his studies on the latter.

The Twelve Categories of Understanding

In the transcendental analytic, Kant distinguishes between two types of concepts: empirical concepts and a priori concepts. The latter are independent of experience and are what Kant calls categories. These are twelve in total, divided into four groups:

1. Quantity
2. Quality
3. Relation
4. Modality (Manner)

The categories, being a priori, are not derived from any experience; rather, they are conditions of the possibility of all experience and learning. Thus, criticizing David Hume, Kant denies an empirical self and defends the existence of a transcendental self. Through pure apperception, this self can synthesize information and thus be aware that not everything can be an object of experience.

Transcendental Dialectic: The Limits of Reason

However, there may be an illegitimate use of the categories when they are not used correctly—that is, when we apply categories to things that cannot be perceived or intuited, such as the concepts of metaphysics: God, the soul, and the world. Hence, Kant enunciated his famous phrase: "Sensible intuitions without concepts are blind, but concepts without intuitions are empty."

Finally, in the Critique of Pure Reason, we find the transcendental dialectic, in which Kant examines the third power of the mind, reason, questioning whether metaphysics is possible as a science.