Critique of Pure Reason

Nonfiction | Book | Adult | Published in 1781

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Summary

Chapter Summaries & Analyses

Prefaces and Introduction

Part I: “Transcendental Aesthetic”

Part II: “Transcendental Logic,” Book I, Chapter I

Part II: “Transcendental Logic,” Book I, Chapter II

Part II: “Transcendental Logic,” Book II, Chapters I-II

Part II: “Transcendental Logic,” Book II, Chapter III

Part II: “Transcendental Logic,” Division II, Books I-II, Chapter I

Part II: “Transcendental Logic,” Division II, Book II, Chapter II

Part II: “Transcendental Logic,” Division II, Book II, Chapter III

Transcendental Doctrine of the Method

Key Figures

Themes

Index of Terms

Important Quotes

Essay Topics

Part II: “Transcendental Logic,” Book II, Chapters I-IIChapter Summaries & Analyses

Transcendental Doctrine of Elements

Part II: Transcendental Logic, Book II: Analytic of Principles, Introduction - Chapter I Summary

Kant transitions to Book II of the “Transcendental Analytic,” the “Analytic of Principles.” Book I dealt primarily with categories of understanding. Now Kant turns to the other fundamental aspect of understanding: the power of judgment. Through an analysis of the principles of judgment, Kant will complete a “canon” of understanding, which includes all its fundamental and basic components and excludes the illusions of reason. Judgment is a unique ability. Some people are better at making judgments than others, though all are equally equipped with the categories of pure understanding. Kant writes that this portion of the transcendental analytic will be divided into two chapters. The first deals with “the schematism of pure understanding” and the second with the principles of understanding.

The so-called “schematism” explains how objects of experience come to be identified with particular concepts. To do this, diverse objects must be made homogenous, or the same as one another, so they can be grouped under one concept. The schematism should show how the concepts of understanding are “applied to appearances as such” (210). Kant makes a distinction between the schema and the schematism. The schema is given by the objects of sensation. Kant writes, “ a schema is, properly speaking, only the phenomenon of an object, or the sensible concept of an object, in harmony with the category” (218). These are the limits on conceptualization received by the mind from the sensible world.

The schematism is the procedure through which the schema is actively adopted by the understanding and appropriately categorized (212). To bridge the divide between the schema and the schematism, Kant invokes the notion of the “schema of imagination” (213). The application of the schema by the imagination is fundamental to the possibility of experience. The categories of the understanding cannot produce objects themselves, though they are the constraints through which objects are possible in experience. Kant muses that the means through which the schematism applies to the schema through the imagination is a “secret art residing in the depths of the human soul,” and speculates that we will never know how this operates (214).

Kant ends this chapter by defining the schema of many important philosophical concepts including substance, reality, causality, actuality, and necessity.

Part II: Transcendental Logic, Book II: Analytic of Principles, Chapter II Summary

In this section, Kant creates a canon of the principles of the categories of pure understanding. These refer to the power of judgment, of which there are two kinds: analytic and synthetic. Each has its own supreme principle on which all others depend.

The supreme principle of analytic judgments is the principle of contradiction, which simply states that any analytic judgment must not contradict itself. The production of synthetic judgments is much more involved and requires the syntheses of sense, imagination, and apperception. The supreme principle of synthetic judgments states that every judgment requires the conditions of unity in possible experience (as were articulated in the previous chapters). The synthetic principles that follow this supreme principle are “universal rules,” Kant writes, “and the objective reality of these rules as necessary conditions can always be shown in experience” (227).

Beginning in Section III, Kant explains the system of these synthetic principles. These principles supersede the laws of nature because they are conditions for the possibility of nature whereas the “laws of nature” are empirically derived rules. Kant divides these synthetic principles (“for the objective use of the categories”) into four distinct kinds: 1. Axioms of intuition 2. Anticipations of perception 3. Analogies of experience and 4. Postulates of empirical thought.

Kant articulates the unique principles of each of these, providing proofs and detailed explanations when applicable. For instance, during his explication of the analogies of experience, he presents a fundamental principle to which all the analogies must conform and then a principle for three distinct analogies. The fundamental principle in this case is that “Experience is only possible through the presentation of a necessary connection of perceptions” (247). The second analogy is the “Principle of Temporal Succession According to the Law of Causality,” and its principle states that causality (from cause to effect) is necessary for the presentation of any change (259). Kant provides a proof why this must be so and how it refers to the fundamental principle of all analogies. He does this for each synthetic principle in the canon until he provides a satisfactory system of principles, which will nearly complete the transcendental analytic.

This protracted section ends with the famous “Refutation of Idealism,” which was added in the second edition in 1787. The idealism Kant is refuting is “material idealism,” which he divides into two types: dogmatic idealism and problematic idealism. Material idealism is the view that the material of the world either does not exist or cannot be proven to exist. The dogmatic idealist, represented by 18th century Irish philosopher George Berkeley, denies the possibility of material reality. The problematic idealist, represented by 17th century French mathematician and philosopher Rene Descartes, thinks that the existence of material reality is doubtful. Kant’s “theorem,” which he uses to challenge idealism, is that material reality is proven by the very fact of self-consciousness.

Part II: “Transcendental Logic,” Book II, Chapters I-II Analysis

In these sections Kant wants to provide a clear and systematic picture of how the concepts of the understanding are applied to experience. To do this, he must show how understanding and sensation are connected. As he’s already noted, without both faculties human experience would not be possible. Kant develops the notion of a strange intermediary faculty called the productive imagination that bridges concepts of our understanding to our sensations, thereby producing the objects of our experience.

The imagination can produce an image of an object through a mysterious power that takes the general concepts of understanding and applies it to the “schema” of sensibility. Kant writes, “we cannot have insight into the possibility of any thing according to the mere category, but must always have available an intuition by which to display the objective reality of the pure concept of understanding” (298). In other words, our faculty of understanding is useless unless it can be united with sensible intuition. This is what the imagination does. In his invocation of the concept of the imagination, Kant is aware that he has reached a point of philosophical explanation past which he cannot progress. The “secret art” of the imagination is hidden from philosophical reflection. All Kant can do is show that there must be such an art, or productive imagination, to link understanding and sensibility, but he cannot show how this art operates.

He will, however, go on to systematically present all “synthetic principles of pure understanding” (229). Recall that synthesis requires uniting different concepts under one object and that experience is predicated on the ability of the mind to perform synthesis. The systematic, i.e., complete, presentation of all these fundamental principles is necessary because Kant’s project is to determine the boundaries of possible experience. It is necessary, then, to classify, present, and prove all these principles since he is not just sketching the limits of experience but striving to totally articulate them.

The principles contained in this section (for instance, the law of causality) are absolute constraints on understanding. Therefore, they cannot be avoided or overcome. By systematically ordering and appropriately organizing them, Kant shows that they are not merely necessary for experience (the ultimate arbiter of any possible truth) but also for any coherent philosophy. For Kant, these principles are “nothing more than a priori principles of the possibility of experience; and all a priori synthetic propositions also refer solely to this possibility” (302). This means that any supposed principle of understanding that cannot be exhibited in actual experience is nonexistent. Any propositions we think up based on these principles must be determinable in actual experience to be legitimate.