 Ultimately, Kant thought, reasons’ necessary, self-driving activity will lead it to produce contradictions—what he called the “antinomies”, which consist of a thesis and antithesis. Once reason has generated the unconditioned concept of the whole world, for instance, Kant argued, it can look at the world in two, contradictory ways. In the first antinomy, reason can see the world (1) as the whole totality or as the unconditioned, or (2) as the series of syllogisms that led up to that totality. If reason sees the world as the unconditioned or as a complete whole that is not conditioned by anything else, then it will see the world as having a beginning and end in terms of space and time, and so will conclude (the thesis) that the world has a beginning and end or limit. But if reason sees the world as the series, in which each member of the series is conditioned by the previous member, then the world will appear to be without a beginning and infinite, and reason will conclude (the antithesis) that the world does not have a limit in terms of space and time (cf. Critique of Pure Reason, A417–18/B445–6). Reason thus leads to a contradiction: it holds both that the world has a limit and that it does not have a limit at the same time. Because reason’s own process of self-development will lead it to develop contradictions or to be dialectical in this way, Kant thought that reason must be kept in check by the understanding. Any conclusions that reason draws that do not fall within the purview of the understanding cannot be applied to the world of experience, Kant said, and so cannot be considered genuine knowledge (Critique of Pure Reason, A506/B534).