There are three main divisions of the _Dialectic_. (The first Kant calls the paralogisms of rational psychology.) All knowing and experience imply the unity of the self which knows. In actual experience that unity is qualified by the nature of what it unites, but we may try to think of it apart from and independent of this. This leads to an attempt to know the self by asking what must be its nature if it has the unity implied in knowing, and to argue that the soul is a substance and simple, not affected by the changes in the matter which it knows and therefore immortal. The second division arises from the fact that in knowledge we are concerned with series--a series of addings together and a series of divisions, as of parts of space and time; a series of things arising one from the other, as in causation; and a series of things in dependence one upon the other. The _ideas_ of reason come from the thought of these series completed, and produce what Kant calls antinomies. For if we start with the thought that what we are trying to apprehend must be a whole, we get one series of results; if with the thought that we can only apprehend the whole by going from condition to condition indefinitely, we get another. Kant distinguishes four antinomies, each with thesis and antithesis. The thesis of the first is, "The world has a beginning in time, and is limited also in regard to space"; the antithesis, "The world has no beginning and no limits in space, but is infinite, in respect both to time and space." The thesis of the second is, "Every compound substance in the world consists of simple parts, and nothing exists anywhere but the simple or what is composed of it"; the antithesis is the contrary of this. The thesis of the third is, "Causality, according to the laws of nature, is not the only causality from which all the phenomena of the world can be deduced. In order to account for these phenomena it is necessary also to admit another causality, that of freedom"; the antithesis, "There is no freedom, but everything in the world takes place entirely according to the laws of nature." The thesis of the fourth is, "There exists an absolutely necessary Being belonging to the world, either as a part or as a cause of it"; the antithesis is a denial of this. The problems of the third division of the _Dialectic_ arises from an attempt to think of a whole which shall include both the known world and the mind that knows. This attempt, which Kant calls the ideal of pure reason, leads to proofs of the existence of God. As the _Dialectic_ proceeds, it becomes clear that Kant has another list to hand. He enumerates, as the three great objects of metaphysical inquiry, God, Freedom, and immortality, and in his discussion of the ideas of reason he treats them principally as attempts to give definite and dogmatic answers to the problems suggested by these three topics.