The Philosophy of Immanuel Kant

by A. D. Lindsay

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.

Kant thought of knowledge as a process of extending the bounds of perception, of piecing together the fragmentary glimpses we get of the world, stretching them out in spatial and temporal determinations that go beyond what we have actually experienced, connecting and linking up the events which we perceive discontinuously. As science extends, the range of our knowledge widens, but the process of extension never reaches its completion. There are always more facts to be discovered and explained. Science, therefore, can never rest content with its achievements, but must always demand that the investigation of conditions should be pushed further back and on. From this sense of the incompleteness of all actual knowledge, and of all there is that might be but is not known, arises what Kant calls an ideal of reason, a demand that, in all investigation into the conditioned, we should go on till we come to the totality of conditions. This ideal he holds to be serviceable and necessary. It has, however, a natural tendency to pass from an ideal to an idea, and in so doing it gives rise to the contradictions with which the Dialectic is concerned. If all our investigation is governed by the thought that it must go on until it reaches completion, we naturally speculate on the fulfilment of that ideal, and try to form an idea of that totality of conditions, of how we should think the world if we knew it in its completeness. Herein we hypostatize the ideal or make it an idea, and we fall into contradiction; for we cannot really know the whole without knowing all its parts. If we give up the slow and never-completed process of knowing one part after another, and try to jump to the idea of the whole, we reach quite contrary results, as we apply to the conception of the whole one or other of two assumptions implied in our investigation of the parts.

Kant sharply distinguishes between the principles of the pure understanding and the ideas of reason. The former are implied in all our knowledge, and the fact that experience is not chaotic confirms them at every moment. The second are ideals which guide knowledge, but are never realised. He calls them ideas of reason, because it is the special task of reason to lay down rules for the proper and complete working of the understanding. This task, he thinks, is exemplified in the logical nature of the syllogism which brings into unity the judgments of the understanding. As he used the forms of judgment as a guiding thread to discover a complete list of categories of the understanding, so he uses the forms of syllogism to discover a complete list of the ideas of reason. In both cases Kant's reference to logical forms is far-fetched. Actually the list in the Dialectic seems to be influenced by a number of considerations not always consistent.

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.

Immortality is the subject of what Kant calls the paralogisms of rational psychology. He argues that all attempts to prove the immortality of the soul by a priori arguments involve an argument of this kind: they begin by noting that death is always dissolution of some kind, that, therefore, what is not made up of parts and cannot be dissolved, cannot die. Then they urge that the soul is not made up of parts, and therefore cannot die. The fallacy in this argument is that it treats the unity of the self as though it were an object of knowledge. We can show that knowledge is only possible if the self has a unity other than that of a spatial whole, but we cannot therefore argue that it must be exactly like a spatial whole, in the sense that death in it can only be brought about by dissolution, but unlike a spatial whole in that in it there is nothing to be dissolved. The real nature of the unity of the self, Kant argues, cannot be known. All we can do is to reject a priori arguments either for or against its immortality.

Freedom is treated in the third antinomy of pure reason, and to that Kant devotes most attention, but others of the antinomies are concerned with the difficulties arising from the application of spatial and temporal determinations to reality as a whole, and to the category of necessity. Kant makes a distinction between the first two and the second two antinomies. It is the first two that express the inadequacy of temporal or spatial determination to reality as a whole. All such determination implies measurement, and measurement is always a relation of part to part. The antitheses of both antinomies express the inadequacy of any number to the expression of the nature of the whole, the thesis the inadequacy of regarding reality as an aggregate or addition of any kind. Each is strong in what it denies, and Kant's solution is that both thesis and antithesis are false, because you cannot apply spatial or temporal determination to the world as a whole.

In contrast the solution of the other antinomies is that both thesis and antithesis are true, and that is possible because they are concerned with different things. The third antinomy arises from the difficulty of applying the category of causation to the world as a whole. The assumption underlying the thesis is not, as is sometimes asserted, merely that the notion of infinity in itself implies a contradiction, but that a determinate result must have a determinate cause. If we think of what actually exists now as having been caused by what has preceded it, we must think of that which has had a determinate result being itself determinate. It is the familiar argument for a first cause. In causation we seem to be relating one event to another event, and are really only putting the question of origination further back. Yet, if we say that therefore we must suppose an absolute origination of change, a beginning of the series, we have to answer the question, How is it possible to think of the originating number of the series? For to think that something can arise from nothing is to contradict the principle of causation.