A category is a pure concept of the understanding . It is a product of the understanding, yet is applicable to objects. This can be the case only if the categories make the objects possible, rather than having to conform to objects. The application of categories to their objects is made through pure principles of the understanding.
Kant listed twelve categories, divided into groups. The main division is into mathematical and dynamical categories. Mathematical categories are single and delineate the properties all objects of experience must have. The categories of quality and quantity are mathematical. Dynamical categories are pair-wise and concern the existence of objects of experience. Categories of relation and modality are dynamical. The full table of categories, based on the table of judgments, is as follows:
Unity
Plurality
Totality
Reality
Negation
Limitation
Relation
Community (Reciprocity between agent and patient)
Possibility and Impossibility
Existence and Non-existence
Necessity and Contingency
