(from: Schopenhauer: Essays and Aphorisms, Introduction, translated and edited by. R.J.

Hollingdale, Penguin, 1970, pp. 18-20)

On Kant, Critique of Pure Reason

… Kant’s undertaking is a new description of the human mind. It falls, he says, into two

parts: the part which receives and the part which thinks (vide – see – Locke’s ‘ideas of

sensation’ and ‘ideas of reflexion’ and Hume’s ‘impressions’ and ‘ideas’). The perceiving

part of the mind receives the impressions conveyed by the senses, and Kant calls these

impressions ‘particulars’; the thinking part is the organ of the understanding and the

objects of the understanding he calls ‘concepts’. The application of concepts to

particulars constitutes ‘synthetic judgments.’ What is a synthetic judgment? ‘Judgment’

is Kant’s term for ‘proposition’, and he first classifies judgments as being either analytic

or synthetic. An analytic judgment 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 judgment is one whose predicate

is not contained in its subject, so that its denial is not a self-contradiction: thus all

judgments (propositions) which, in ordinary terms, ‘say something’ are synthetic. Now

synthetic judgments are also of two kinds: a posteriori and a priori. A synthetic a

posteriori judgment is one whose truth or falsity can be determined by experience.

(Example: cake is fattening.) A synthetic a priori judgment 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 judgments are all synthetic a

priori.

What he has done up to this paint 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 a

priori synthetic judgments 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 judgment 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 judgments consist in applying the

categories to the perceptions of sense in space and time. 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 judgments 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 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).