Causation, then, and the other assumptions of the physical sciences, are shown by Kant to be "grounds of the possibility of experience." We cannot deny them without denying elementary distinctions in our experience, without which life would be a chaos, and which are assumed and justified every moment. While Kant thus demonstrates the validity of such principles, he is also insistent on the limitations of their application. They are principles which give consistency to experience, but must not be applied save in reference to what we experience. They apply, in his words, "only to phenomena." The purport of this limitation can, again, be most easily seen by examining the principle of causality. By means of that principle we connect one event with another, but the reality is not two different but connected events, but a continuous process. The continuous process escapes us, because our perception of it is fragmentary and discontinuous. Inasmuch as a judgment of causal connection asserts that the events we separately notice are connected, it is true, but it is false if taken to imply that reality consists of a series of discontinuous events or stages which are yet connected. Such an assumption would mean, in Kant’s words, that causation is applied not to phenomena (things as they appear to us), but to things in themselves (things considered apart from the manner in which they appear to us). If we realise its falsehood, we can, he thinks, evade the contradictions which he examines in the _Dialectic_. *CHAPTER V* *THE ANTINOMIES AND CRITICISM OF THE PROOFS OF THE EXISTENCE OF GOD* So far we have been considering the positive side of Kant’s argument, his attempt to confirm the validity of the principles of science. We must now notice the negative side, his attempt to limit the application of these principles, and his denial of the possibility of knowledge in certain spheres. We saw that Kant in his _Prolegomena_ summed up the argument of the three chief divisions of the _Critique_ as an answer to the questions: How is mathematics possible? How is pure science of nature possible? and, How is metaphysics possible? He qualified the last question by adding "as a natural disposition of the mind." The argument of the _Dialectic_ is that metaphysics, in the sense of inquiry into objects which transcend the bounds of experience, is not possible as a science, but that metaphysical questions arise naturally from the nature of human reason. They cannot be answered. All we can do is to see why we cannot answer them.