An analytic judgement is one whose predicate is contained in its subject, so that its denial is a self-contradiction. (Example: all mothers are female – analytic because ‘mother’ means ‘a female parent’.) A synthetic judgement is one whose predicate is not contained in its subject, so that its denial is not a self-contradiction: thus all judgements (propositions) which, in ordinary terms, ‘say something’ are synthetic. Now synthetic judgements are also of two kinds: a posteriori and a priori. A synthetic a posteriori judgement is one whose truth or falsity can be determined by experience. (Example: cake is fattening.) A synthetic a priori judgement is one which is independent of experience. (Example: every event has a cause – synthetic because its predicate is not contained in its subject, a priori because it is independent of experience, vide Hume.) And Kant maintains that scientific, mathematical and moral judgements are all synthetic a priori.

What he has done up to this point is to define the type of proposition asserted by Hume to be impossible. We cannot say ‘A causes B’, Hume had declared, because we cannot know it. Kant's retort is that we do say ‘A causes B’ and a great many more things of the same kind: and his concern is to discover how it comes about that we do so. How are synthetic a priori judgements possible? is the question he asks. His answer is as follows: The concepts – the objects of the understanding – are of three types: a posteriori (abstracted from sense perception and applied to it), a priori (applicable to sense perception but not abstracted from it), and a third type called Ideas, which are concepts neither abstracted from sense perception nor applicable to it. The a priori concepts of science and other forms of knowledge he calls ‘categories’. Consider ‘Every event has a cause’: this synthetic a priori judgement is not derived from sense perception, since causation cannot be perceived, but it is applied to the objects of sense perception: the concept of causation is thus an a priori concept, and causation is thus a category. There are twelve categories in all. Synthetic a priori judgements consist in applying the categories to the perceptions of sense in time and space. Sense perception in time and space he calls the perceptual manifold: the categories are not derived from the manifold but imposed upon it, and this – the imposition of the categories upon the perceptual manifold – constitutes ‘thinking’. It will now follow that an ‘object’ is that which is capable of conforming to the categories; if it cannot do so, it cannot exist for a human observer. The answer to the question ‘How are synthetic a priori judgements possible?’ is that they are the structure imposed by the mind upon the world.

But see what follows then: if the mind imposes a certain structure upon the world in order to apprehend it, this presupposes that the world upon which this structure is imposed exists independently of it, that there must exist something upon which to impose it: and this something Kant calls the ‘thing in itself’ – the object of perception as it ‘really’ is, before and independently of the imposition of the categories of reason. The object as perceived under the forms of the categories he calls ‘phenomenon’ or ‘appearance’. The ultimate conclusion is that there are two worlds: the ‘real’ world (the thing in itself) and the ‘apparent’ world (the world of phenomena).

I have recited all this Kantian jargon, and thus risked boring the reader unfamiliar with it, partly because Kant's ideas are essentially incommunicable without it and it is thus a paradigm of that technical vocabulary which has always hindered appreciation of German philosophy and concealed the personalities of German philosophers, but partly also to try to bring home the seeming inevitability with which, at the stage of thought we are concerned with, mankind must divide the world in which it lives into two worlds, the one immediate and visible but of an inferior degree of reality, the other hidden, requiring discovery, but more real. In its popular acceptance Kant's philosophy has always meant above all a rigorously scientific demonstration that appearance is not reality.

Now if he is able to remember all that has gone before, I believe the reader will not experience any sense of shock when introduced to a philosophy which begins with ‘The world is my idea’ and ends by asserting that the physical universe, with its stars and galaxies and Milky Ways, is ‘nothing’, but that the philosophy of Schopenhauer will, as metaphysics, seem to him no more than a natural continuation of the fundamental drift of the human mind.

The World as Will and Idea

 

Schopenhauer thought that he alone had understood Kant correctly, and he dismissed Kant's other successors, especially Hegel, as charlatans. His first act is to interpret Kant in a Berkeleian sense: he equates Kant's phenomena with Berkeley's ideas in the mind and says with Berkeley that the world as it is perceived is a creation of the intellect which perceives it. This he takes to have been proved by Kant, but in any case self-evidently obvious; so that he is able to open the book in which he expounds his philosophy, The World as Will and Idea, with the flat assertion ‘The world is my idea’. This takes care of ‘idea’: but what about ‘my’? what of the ‘I’ which has the idea? Schopenhauer thinks the existence of this ‘I’ an absolute necessity, in the same way as the existence of an ‘apparent’ world makes necessary the existence of a ‘real’ world: and in fact this ‘I’ is the real world, the substratum of the world of phenomena. Now it will be clear that if we have knowledge of ourselves, of this ‘I’, it will be a different kind of knowledge from that which we have of anything else. All other kinds of knowledge amount to establishing relations between ideas, but knowledge of oneself would be knowledge of immediate reality. And this is what Schopenhauer maintains knowledge of oneself actually is. We know ourselves objectively, in the same way as we know all other phenomena, as an object extended in space and time: we know ourselves as body. But we also know ourselves subjectively, we have an inner consciousness of our own existence, and we possess feelings and desires. This inner world Schopenhauer calls ‘will’: we know ourselves as will. And thus there follows the ‘single thought’ which, properly understood, Schopenhauer says constitutes the whole of his philosophy: ‘My body and my will are one’.