We assume a common sense as the necessary condition of the universal communicability of our knowledge, which is presupposed in every logic and every principle of knowledge that is not one of skepticism.
Upon the solution of this problem, or upon sufficient proof of the impossibility of synthetical knowledge a priori, depends the existence or downfall of metaphysics.
Ghost stories are always listened to and well received in private, but pitilessly disavowed in public. For my own part, ignorant as I am of the way in which the human spirit enters the world and the way in which he goes out of it, I dare not deny the truth of many such narratives.
Natural science physics contains in itself synthetical judgments a priori, as principles. ... Space then is a necessary representation a priori, which serves for the foundation of all external intuitions.
In the natural state no concept of God can arise, and the false one which one makes for himself is harmful. Hence the theory of natural religion can be true only where there is no science; therefore it cannot bind all men together.