Concepts and ideas, then, though themselves part of the Given, yet at the same time take us beyond the Given. Thus, they make it possible to determine also the nature of the other modes of cognitive activity.

By means of a postulate, we have selected a special part out of the given world-picture, because it is the very essence of knowledge to proceed from a part with just this character. Thus, we have made the selection solely in order to be able to understand knowledge. But, we must clearly confess to ourselves that by this selection we have artificially torn in two the unity of the given world-picture. We must bear in mind that the part which we have divorced from the Given still continues, quite apart from our postulate and independently of it, to stand in a necessary connection with the world as given. This fact determines the next step forward in the Theory of Knowledge. It will consist in restoring the unity which we have destroyed in order to show how knowledge is possible. This restoration will consist in thinking about [320]the world as given. The act of thinking about the world actually effects the synthesis of the two parts of the given world-content—of the Given which we survey up to the horizon of our experience, and of the part which, in order to be also given, must be produced by us in the activity of cognition. The cognitive act is the synthesis of these two factors. In every single cognitive act the one factor appears as something produced in the act itself and as added to the other factor which is the pure datum. It is only at the very start of the Theory of Knowledge that the factor which otherwise appears as always produced, appears also as given.

To think about the world is to transmute the given world by means of concepts and ideas. Thinking, thus, is in very truth the act which brings about knowledge. Knowledge can arise only if thinking, out of itself, introduces order into the content of the world as given. Thinking is itself an activity which produces a content of its own in the moment of cognition. Hence, the content cognised, in so far as it has its origin solely in thinking, offers no difficulty to cognition. We need only observe it, for in its essential nature it is immediately given to us. The description of thinking is also the science of thinking. In fact, Logic was never anything but a description of the forms of thinking, never a demonstrative science. For, demonstration occurs only when there is a synthesis of the products of thinking [321]with a content otherwise given. Hence, Gideon Spicker is quite right when he says in his book, Lessing’s Weltanschauung (p. 5): “We have no means of knowing, either empirically or logically, whether the results of thinking, as such, are true.” We may add that, since demonstration already presupposes thinking, thinking itself cannot be demonstrated. We can demonstrate a particular fact, but we cannot demonstrate the process of demonstrating itself. We can only describe what a demonstration is. All logical theory is wholly empirical. Logic is a science which consists only of observation. But if we want to get to know anything over and above our thinking, we can do so only with the help of thinking. That is to say, our thinking must apply itself to something given and transform its chaotic into a systematic connection with the world-picture. Thinking, then, in its application to the world as given, is a formative principle. The process is as follows. First, thinking selects certain details out of the totality of the Given. For, in the Given, there are strictly no individual details, but only an undifferentiated continuum. Next, thinking relates the selected details to each other according to the forms which it has itself produced. And, lastly, it determines what follows from this relation. The act of relating two distinct items of the world-content to each other does not imply that thinking arbitrarily determines something about them. Thinking [322]waits and sees what is the spontaneous consequence of the relation established. With this consequence we have at last some degree of knowledge of the two selected items of the world-content. Suppose the world-content reveals nothing of its nature in response to the establishment of such a relation, then the effort of thinking must miscarry, and a fresh effort must take its place. All cognitions consist in this, that two or more items of the Given are brought into relation with each other by us and that we apprehend what follows from this relation.

Without doubt, many of our efforts of thinking miscarry, not only in the sciences, as is amply proved by their history, but also in ordinary life. But in the simple cases of mistake which are, after all, the commonest, the correct thought so rapidly replaces the incorrect, that the latter is never, or rarely, noticed.

Kant, in his theory of the “synthetic unity of apperception,” had an inkling of this activity of thought in the systematic organisation of the world-content, as we have here developed it. But his failure to appreciate clearly the real function of thinking is revealed by the fact, that he believes himself able to deduce the a priori laws of Pure Natural Science from the rules according to which this synthetic activity proceeds. Kant has overlooked that the synthetic activity of thinking is merely the preparation for the discovery of natural laws properly so-called. Suppose we select two [323]items, a and b, from the Given. For knowledge to arise of a nexus according to law between a and b, the first requirement is that thinking should so relate a and b, that the relation may appear to us as given. Thus, the content proper of the law of nature is derived from what is given, and the sole function of thinking is to establish such relations between the items of the world-picture that the laws to which they are subject become manifest. The pure synthetic activity of thinking is not the source of any objective laws whatever.

We must inquire what part thinking plays in the formation of our scientific world-picture as distinct from the merely given one. It follows from our account that thinking supplies the formal principle of the conformity of phenomena to law. Suppose, in our example above, that a is the cause, b the effect. Unless thinking were able to produce the concept of causality, we should never be able to know that a and b were causally connected. But, in order that we may know, in the given case, that a is the cause and b the effect, it is necessary for a and b to possess the characteristics which we mean when we speak of cause and effect. A similar analysis applies to the other categories of thought.

It will be appropriate to notice here in a few words Hume’s discussion of causality. According to Hume, the concepts of cause and effect have their origi............