Kant, Immanuel (1724–1804)

6. Pure concepts of the understanding

The ‘Transcendental Analytic’ of the Critique breaks new ground, arguing that the most fundamental categories of thought as well as the forms of perception are themselves human products which are necessary conditions of the possibility of experience. Like the ‘Transcendental Aesthetic’, its first section, the ‘Analytic of Concepts’, is also divided into a ‘metaphysical’ and a ‘transcendental deduction’ (B 159).

In the metaphysical deduction Kant intends to provide a principle to identify the most fundamental concepts of thought, the categories of the understanding, and then to show that our knowledge of any object always involves these categories. The key to his argument is the claim that knowledge is always expressed in a judgment (A 68–9/B 93–4); he then argues that there are certain characteristic forms or ‘logical functions’ of judgment, and that in order for our judgments to be about objects, these logical functions of judgments must also provide the basic concepts for conceiving of objects. Thus Kant first produces a table of the logical functions of judgment, based on the premise that every judgment has a quantity, quality, relation and modality, and then produces a table of categories, under the same four headings, showing how objects of such judgments must be conceived. Thus, judgments may be universal, particular, or singular, and then their objects must be unities, pluralities, or totalities; judgments may be affirmative, negative, or infinite, and objects manifest either reality, negation, or limitation; judgments may relate a predicate to a subject (categorical judgment), or else relate one predicate-subject judgment to another as antecedent and consequent (hypothetical judgment) or as alternatives (disjunctive judgment), and objects may correspondingly manifest the relations of inherence and subsistence, causality and dependence, or community or reciprocity; finally, judgments may be problematic, assertoric, or apodeictic, thus their objects either possible or impossible, existent or non-existent, or necessary or contingent (A 70/B 95; A 80/B 106).

Kant’s scheme is intuitively plausible, and he makes use of it throughout his works. But philosophers as diverse as Hegel and Quine have questioned its coherence and necessity. What is troubling for Kant’s own project, however, is that he does not show why we must use all the logical functions of judgment, hence why we must use all the categories. In particular, he does not show why we must make not only categorical but also hypothetical and disjunctive judgments. Without such a premise, Kant’s arguments for causation, against Hume, and for interaction, against Leibniz, are not advanced. It is unclear whether Kant recognized this defect in the argument of the metaphysical deduction. But he addressed precisely this problem in the subsequent chapter on the ‘System of all Principles of Pure Understanding’, which does attempt to demonstrate the necessity of the use of each of the categories. This chapter will be discussed in the following section

Kant’s aim and his strategy in the transcendental deduction remain debatable, despite his complete revision of this section in the second edition of the Critique. Some view the transcendental deduction as a ‘regressive argument’ aimed at empiricism, meant to show only that if we make judgments about objects then we must use a priori concepts. But if Kant already established this in the metaphysical deduction, the transcendental deduction becomes redundant. It seems more natural to see the latter as intended to fix the scope of our use of the categories by showing that we can have no experience which is immune from conceptualization under them, thus that the categories enjoy universal objective validity. Because these categories originate in the logical structure of our own thought, Kant holds, we must conceive of ourselves as the autonomous lawgivers for all of nature (A 127–8, B 164).

There are many differences between the two versions of the transcendental deduction, but both employ the fundamental idea that we cannot have some form of self-consciousness, or ‘transcendental apperception’, without also having consciousness of objects, which in turn requires the application of the categories; then, since Kant holds that we can have no experience at all without being able to be conscious that we have it, he can argue that we can have no experience to which we cannot apply the categories. The success of this strategy is unclear. The first-edition deduction begins with a debatable analysis of the necessary conditions for knowledge of an object, which slides from the conditional necessity that we must use rules if we are to have knowledge of objects to an absolute necessity that we must have knowledge of objects, and then introduces transcendental apperception as the ‘transcendental ground’ of the latter necessity (A 106). In the second edition, Kant begins directly with the claim that self-consciousness of our experience is always possible, which has not met with much resistance, but then makes the inference to the necessity of knowledge of objects conceived of through the categories by equating transcendental apperception with a notion of ‘objective apperception’ that is equivalent to judgment about objects (B 139–40). This makes the connection between self-consciousness and the categorial judgment of objects true by definition, and undermines Kant’s claim to provide a synthetic rather than analytic proof of the objective validity of the categories.

In spite of these problems, the idea that self-consciousness depends upon knowledge of objects and thus on the use of the categories to conceive of objects has remained attractive; and some of the most interesting recent work on Kant has been reconstructions of the transcendental deduction, such as those by Peter Strawson, Jonathan Bennett and Dieter Henrich. Others have concluded that Kant only establishes a convincing connection between self-consciousness and categorial thought of objects once he shows that making judgments about objects, using the categories, is a necessary condition for making judgments about the temporal order of our experience. This is Kant’s project in the next section of the Critique.