Wolff’s twofold world may be thus compared with Kant’s threefold world:—
| Wolff. | Kant. |
|---|---|
| 1. Mind. | 1. Subjective states. |
| 2. Phenomena—the realm of knowledge. | |
| 2. Matter. | 3. Things-in-themselves. |
1. The realm of subjective states evidently is not a realm of knowledge. For it is the realm of intuition and immediate apprehension of the individual’s own ideas and sensations; and this is not what we mean by knowledge. This subjective world is that in which I live alone. It is a realm of which nobody else is conscious, a realm which gives to me my individuality. The only connecting linkage between my various purely subjective states is the accidental order of time in which, empirically or by association, they occur. Animal intelligencepossesses only such sense-perceptions and sensations, and these are modifications of its subjective consciousness. Such a mental constitution has not the capacity for knowledge, but only the haphazard association of ideas. Kant looked upon the content of subjective consciousness as the object only of psychological investigation.
2. The realm of things-in-themselves is not to Kant the realm of knowledge. By things-in-themselves Kant distinctly does not mean things-for-us, not material bodies, not nature objects. It must be remembered that Kant has plundered the material realm of the dualist. The things-in-themselves which are left behind as a residuum lie outside all sense-perception and so beyond all knowledge. A divine intelligence might have the things-in-themselves as objects of knowledge, but not we human beings. The thing-in-itself is the unknown and unknowable. But if this realm of things-in-themselves is so absolutely independent of us that we cannot in any way know it, how can we say that it exists? Kant replies to this: while we cannot say what a thing-in-itself is, we are obliged to say that it is. For although beyond even our sense-perception, it stands as a necessary postulate to perception, as a mere “problem.” Kant also calls things-in-themselves Noumena, and regards them as “limiting concepts” to the divine non-sensuous intelligence. Their reality is as little to be denied as affirmed.
3. Kant pointed out that between or beside the realm of subjectivity and that of the things-in-themselves lies the realm of human knowledge, which we in our every-day speech call physical nature, and to which he gave the name “the world of phenomena” or “theworld of experience.” The subjective world is apprehended by the individual alone, the world of things-in-themselves is known by no human being, but the world of phenomena is the common object of knowledge of humanity. Phenomena are not things-in-themselves, but things-for-us; they are physical nature, an interrelated totality for us. They constitute not absolute reality, but a reality relative to us. Phenomena are experiences in their relations; such related experiences are objects of knowledge, and in their thoroughly organized and systematic form they constitute nature.
Thus the dualism which we ordinarily meet, like the “two world” theory of Wolff, has many differences from this critical theory of Kant with its threefold divisions of one world. One of the most important is that in Kant’s theory the correspondence between states of consciousness and reality has disappeared. Reality touches consciousness only at one point,—at that point where sensations arise. Sensations mark the boundary between unknown reality and conscious life. On the side of reality all is darkness; on the side of conscious life all is the creation of our complex synthetic activity. With the boundary line of sensation as a base, the two realms extend in opposite directions. In value the realm of our conscious life is only relative; that of reality or things-in-themselves is absolute.
The World of Knowledge. There is this to be observed about the threefold realm of Kant: the realm of subjectivity and that of knowledge together make up our conscious life. One is the realm of the conscious individual, and the other the realm of the consciousness of humanity. Kant conceived this further distinction between the two realms: in a purely subjective statethe mind is entirely passive and its content is without control; in a state of knowing the mind is actively engaged in collecting and relating its ideas. This is called by Kant synthesis.
When Kant was formulating his problem, there gradually came to him in clearer outline the synthetic nature of the activity of the human reason. He felt more and more that the secret of the knowing process was to be explained by its function of combining many experiences into a unity. This conception of synthesis is what separates the Critique of Pure Reason from all the previous writings of Kant. Furthermore, the three books of the Critique are expositions of the different stages in which mental synthesis completes itself: in (1) perception, (2) understanding, and (3) reason. The knowing activity of man develops in these three different forms of synthesis, in which each lower stage is the content of the higher.
What, then, is the central factor in knowledge? It is the synthetic power of the mind. The mind is not merely passively aware of its sensations as they come seriatim, but it actively relates them and holds them together. The mind is a dynamic agent whose activity consists in synthesizing in the present moment its experiences of the past. The human mind is not like a curtain upon which stereopticon pictures appear and then disappear in turn. It retains its pictures, although they are no longer being thrown upon the screen. Suppose we hear the ticking of a clock. Now if we had no synthetic power, all we should apprehend would be one, one, one,—and so on. But we do have synthetic power, and we say one, two, three, and so on. We count in a series in which each term includes the precedingterm. Two includes one, and three includes two, etc. This is knowledge. It is cumulative experience. The experience of twenty animals, each having one experience, is not the same as the experience of one man having twenty experiences. In vain would nature act on man if the mind of man through memory and imagination did not carry over experiences. So the important thing is not what happens, but what power the human mind has. Knowledge, then, to Kant is the unifying of the manifold.
There are, therefore, two aspects to knowledge; the passive sensations and the active power of synthesis. Sensations, on the one hand, are the raw material out of which reason through its various forms creates the finished fabric of knowledge. Sensations are the content of knowledge. On the other hand, there is the active unifying power of the reason. Knowledge consists of sensations and synthesis in conjunction. Reason alone deals with “thought relations” or imaginations, whenever it tries to treat objects of which sensations are not the raw material. Sensations alone, however, are only subjective states. The oft-quoted sayings of Kant, that “Only in experience is the truth,” and that “Conception without perception is empty, perception without conception is blind,” refer to the restriction of knowledge to the sense-materials and to the synthetic function of the reason.