It is here that the usefulness of a system of categories shows itself so plainly and unmistakably, that, even were there not several other proofs of it, this alone would quite sufficiently demonstrate its indispensableness in the system of pure Reason. There are not more than four of these transcendent ideas, as many as there are classes of categories; but each of them is only concerned with the absolute completion of a series of conditions to a given conditioned. In accordance with these cosmological ideas there are four dialectical assertions of pure Reason, which, inasmuch as they are dialec- tical, show that to each one is opposed a contradictory assumption, on equally plausible principles of pure Reason; and this is a conflict no metaphysical art of the subtlest distinction can avoid, but which compels philosophers to go back to the primary sources of pure Reason. The above antinomy, which is not arbitrarily invented, but has its basis in the nature of human Reason, and is hence unavoidable and never-ending, contains the following four theses together with their antitheses:
- The world has a beginning in time and space
- Everything in the world consists of simple[parts].
- There are in the world causes through freedom.
- In the series of world-causes there exists a necessarybeing.
- The world is infinite in time and space
- There is nothing simple, but everything is composite.
- There is no freedom, but all is Nature
- There is nothing necessary, but in this series alliscontingent.