Categories

3. Three important systems of categories: Kant

The system of categories presented in Kant’s Critique of Pure Reason is a clear example of a categorial system based on the structure of our cognitive capacities. Kant identifies the categories as necessary preconditions for the application of judgment to objects. All judgments have to have four features: a quantity, a quality, a relation, and a modality. The quantity determines whether we are dealing with a judgment of all, of some, or of a single one (‘All swans are black’, ‘Some swans are black’, ‘There is a black swan’), while the quality tells us whether a judgment is affirmative (‘The swan is black’), negative (‘The swan is not black’), or infinite (an example of the this kind of judgment could be a judgment like ‘the soul is immortal’; it is not negative, since the copula is not negated, nor is it affirmative, since it contains a negative predicate). Relation settles whether a judgment is categorical (‘Swans are black’), hypothetical (‘If swans are black, ravens are white’), or disjunctive (‘Swans are black or white or blue …’), and modality distinguishes between problematic (‘Possibly, swans are black’), assertoric (‘Swans are actually black’), and apodictic judgments (‘Necessarily, swans are black’). These then give rise to four triples of categories: unity, plurality, and totality; reality, negation, and limitation; substance, causation, and community; and finally possibility, existence, and necessity.

The question whether this list picks out items in the world, mediated by a theory of very general structural features of our judgments of the world, is complex. This is largely due to the fact that ‘in the world’ in the Kantian case has to be understood as belonging to the noumenal realm of things in themselves. This noumenal realm constitutes the world as it is independent of the structuring activity of the human mind. For Kant such a realm has to exist, but there is not much else we can say about it. In particular the assumption that any categories at all can be applied to this realm is highly doubtful.

Nevertheless, the contrast between the Kantian system of categories and those of Aristotle and the Vaiśeṣikasūtra is striking: for them the ontological categories are clearly things in the world, while our grammatical, linguistic, and other epistemic abilities are routes to these categories, but not of primary interest themselves. For Kant, the position is reversed. Investigating the structure of our epistemic access to the world is primary, this is what delivers the contents of our theory of ontological categories. Whether these categories have worldly equivalents is, if it is answerable at all, of secondary importance. For Kant there is a significant chasm between the basic structural features of our mind, and basic structural features of the world that is simply not there for a philosopher like Aristotle. As such, the Kantian theory of categories is firmly located on the ‘mind’-side of this chasm.