A Short History of Modern Philosophy: From Descartes to Wittgenstein, Second Edition (21 page)

Of diminutive stature and austere habits, Kant was nevertheless a gregarious man, a brilliant talker, and a loved and respected member of social and literary circles. He was a founding spirit of the German Romantic movement which was to change the consciousness of Europe, and also the father of nineteenth-century idealism. He was (and remains) the greatest philosopher since Aristotle, and his most important book— the
Critique of Pure Reason
—is of an intellectual depth and grandeur that defy description. Mme de Staël wrote of it thus:

His treatise on the nature of the human understanding, entitled the 'Examination of Pure Reason', appeared nearly thirty years ago, and this work was for some time unknown; but when at length the treasures of thought which it contains were discovered, it produced such a sensation in Germany, that almost all which has been accomplished since in literature as well as in philosophy, has flowed from the impulse given by this performance.

I shall devote this chapter to a discussion of that work, leaving the ethics, the aesthetics and the vagaries of Kant’s immediate influence to the chapter which follows.

Kant’s early philosophical inspiration had been the system of Leibniz, as expounded by Wolff (see chapter 6). But despite this influence—which is everywhere apparent in the
Critique of Pure Reason
—Kant’s philosophy is unique, both in its methods and in its aims. In order to understand those aims we must again consider the impact, during the seventeenth and eighteenth centuries, of the rise of science. Science presented itself as a universal discipline, the premises of which were certain, and the methods of which were disputable only by the adoption of a stance of philosophical scepticism. No one could engage in science without accepting both the established results of his predecessors, and also the empirical methods that led to their discovery. Science presented a picture of unanimity and objectivity which no system of metaphysics could rival. Forced by this fact into unnatural self-consciousness, philosophy found itself with no results that it could offer as its own peculiar contribution to the fund of human knowledge. The very possibility of metaphysics was thrown in doubt, and this doubt was only exacerbated by Hume’s radical scepticism—a scepticism which, according to Kant, aroused him from his ‘dogmatic [by which he meant Leibnizian] slumbers’. All philosophy, then, for Kant, must begin from the question ‘How is metaphysics possible?’

In answer to that question, Kant attempted a systematic critique of human thought and reason. He tried to explore not just scientific beliefs, but all beliefs, in order to establish exactly what is presupposed in the act of belief as such. He wished to describe the nature and limits of knowledge, not just in respect of scientific discovery, but absolutely: his metaphysics was designed, not as a postscript to physics, but as the very foundation of discursive thought. He hoped to show three things:

1. That there is a legitimate employment of the understanding, the rules of which can be laid bare, and that limits can be set to this legitimate employment. (It is a striking conclusion of Kant’s thought that rational theology is not just unbelievable, but unthinkable.)
   
2. That Humean scepticism is impossible, since the rules of the understanding are already sufficient to establish the existence of an objective world obedient to a law of causal connection.
   
3. That certain fundamental principles of science—such as the principle of the conservation of substance, the principle that every event has a cause, the principle that objects exist in space and time, can be established
   a priori.
   

Kant’s proof of these contentions begins from the theory of ‘synthetic
a priori
’ knowledge. According to Kant, scientific knowledge is
a posteriori
: it arises from, and is based in, actual experience. Science, therefore, deals not with necessary truths but with matters of contingent fact. However, it rests upon certain universal axioms and principles, which, because their truth is presupposed at the start of any empirical enquiry, cannot themselves be empirically proved. These axioms are, therefore,
a priori,
and while some of them are ‘analytic’ (true by virtue of the meanings of the words used to formulate them), others are ‘synthetic’, saying something substantial about the empirical world. Moreover, these synthetic
a priori
truths, since they cannot be established empirically, are justifiable, if at all, through reflection, and reflection will confer on them the only kind of truth that is within its gift: necessary truth. They must be true in any conceivable world. (Kant’s idea of necessity is here weaker than that of Leibniz, for whom necessity meant truth in every
possible
world; see pp. 69-70.) These truths, then, form the proper subject matter of metaphysics; the original question of metaphysics has become: ‘How is synthetic
a priori
knowledge possible?’

Kant compared his answer to that question (to which he gave the vivid name ‘transcendental idealism’) to the Copernican revolution in astronomy, because, like Copernicus, he had moved away from the narrow vision which sees one thing as central, towards a wider vision from which that one thing (in this case the capacities of the human understanding) can be surveyed and criticised. There is an immediate intellectual difficulty of which Kant was aware, and which provides the explanation of the word ‘transcendental’ (a technical term which has as little to do with ‘Transcendental Meditation’ as with Liszt’s
Transcendental Studies).
Consider the question ‘How is logic possible?’ What argument could there be for the principles of logic that did not already presuppose them? Analogously, if the synthetic
a priori
principles of the understanding are as fundamental to thought as Kant asserted, then the very attempt to establish their validity must at the same time assume them. It was for this reason that Kant called his philosophical method ‘transcendental’, since it contained an attempt to transcend through argument what argument must presuppose. Not surprisingly, the possibility of such ‘transcendental argument’ has been the object of continual scepticism. Nevertheless, the individual conclusions of the
Critique of Pure Reason
are of such interest, and often of such intrinsic plausibility, that Kant’s own theory as to the nature of his method has dissuaded only the most fatuously common-sensical from trying to reconstruct his argument.

Kant believed that neither the empiricists nor the rationalists could provide a coherent theory of knowledge. The first, who elevate experience over understanding, deprive themselves of the concepts with which experience might be described (for no concept can be derived as a mere ‘abstraction’ from experience); while the second, who emphasise understanding at the expense of experience, deprive themselves of the very subject matter of knowledge. Knowledge is achieved through a synthesis of concept and experience, and Kant called this synthesis ‘transcendental’, meaning that it could never be observed as a process, but must always be presupposed as a result. Synthetic
a priori
knowledge is possible because we can establish that experience, if it is to be subject to this synthesis, must conform to the ‘categories’ of the understanding. These categories are the basic forms of thought, or
a priori
concepts, under which all merely empirical concepts are subsumed. (For example, the concept ‘table’ is subsumed under ‘artifact’, which in turn is subsumed under ‘object’ and hence under ‘substance’; the concept of ‘killing’ is subsumed under ‘action’, which falls under ‘cause’. The categories are the end-points of these chains of subsumption, points beyond which one cannot proceed, since they represent the most basic operations of human thought.) Thus we can know
a priori
that our world (if it is to be
our
world) must obey certain principles, principles implicit in such concepts as substance, object and cause, and that it must fall under the general order of space and time.

The cornerstone of this anti-sceptical proof occurs in a famous, but extremely obscure, passage of the
Critique of Pure Reason,
known as ‘The Transcendental Deduction of the Categories’. This exists in two versions, corresponding to the two editions of the
Critique of Pure Reason,
and it is hard to say which version is to be preferred, since neither is fully intelligible. But the outline of the argument can be displayed, and it can be seen that, if valid, it is one of the most important arguments in the whole of philosophy.

Like Descartes, Kant begins from an examination of an aspect of selfconsciousness. But, unlike Descartes, he uses his arguments in order to reject what I have called ‘the priority of the first person’. In other words, he removes the privileges from subjectivity, and in doing so destroys the possibility of an empiricist theory of the mind. The immediate result is that epistemology becomes secondary to metaphysics; for without metaphysics the deliverances of the senses become impossible to describe.

Kant’s near contemporary Lichtenberg remarked that Descartes should have said not, ‘I think’, but only, ‘It thinks in me’. However, as Kant recognised, there is contained in the idea of a thought, as of every mental content, the notion of a subject. Moreover, this subject has an immediate and intuitive apprehension of its own unity: I know immediately of my present mental states that they are mine, and in the normal case I cannot be wrong about this. (In other words, in the case of the present contents of the mind, the distinction between being and seeming evaporates. This is what is meant by the ‘subjectivity’ of the first person.) It is impossible that I should be in the position of Mrs Gradgrind (in
Hard Times),
who, on her deathbed, knew only that there was a pain in the room somewhere, but not that it was hers. Nor do I have to
find out
that my pain and my thought belong to a single consciousness. My having these states presupposes my ability to assign them to the single subjective unity of the self.

Kant refers to this unity as the ‘Transcendental Unity of Apperception’, ‘apperception’ meaning self-consciousness, and the word ‘transcendental’ indicating that the ‘unity’ of the self is not known as the conclusion of an argument but as the presupposition of all self-knowledge. Now this unity is not a mere ‘binding force’ among mental items; it is what Kant calls an ‘original’ unity. It consists, in other words, in the existence of a thing (the subject), which bears its mental states not as adjuncts but as properties. The very idea of self-knowledge leads us therefore to the unity of the self, as an entity over and above the totality of its mental contents. It follows that there is more to the self than present selfknowledge can offer. The self has an identity (and in particular, an identity through time) beyond the mere collection of its present thoughts and feelings. Hence, while I may have immediate knowledge of my present mental states, there are other aspects of myself about which I might be mistaken, and about which I might have to find out. I might have to discover the truth about my past and future. Hence the self as subject presupposes the self as object. While there is an area of self-knowledge which is subjective (where the distinction between being and seeming evaporates), this is possible only because the self has an enduring, objective identity, in other words, only because it may also be other than it seems. So a subject of experience, if it is to have knowledge of itself as subject, must inhabit an objective world, a world in which the general concept of an object finds application. Radical scepticism, which can be stated only from the premise of self-knowledge, therefore presupposes its own falsehood.

According to Kant, the Transcendental Deduction establishes the validity (in some sense) of the general concept of objectivity. It remains to discover what that concept contains, and it is here that we must turn again to the theory of the categories. Kant argues that all knowledge involves the application of concepts to experience. Having shown that no knowledge is possible, not even self-knowledge, without the general concept of an object, we can at once conclude that experience must conform to the strictures which that concept contains. In other words, experience must conform to the categories; for these are nothing more than a working out in detail of all that is contained in the abstract concept of objectivity. Thus I cannot think in terms of objects without thinking of entities that endure through change; this requires that I apply to my experience the concept of substance. But substance, in its turn, involves the idea of something that sustains itself in being, and that idea involves the notion of causality (or causal explanation). Causality in turn requires the idea of a law of nature, and hence the notions of necessity, possibility and actuality. And so on. Thus we see that, from the assumption that experience falls under the concept of an object, we arrive at the conclusion that it must fall under all the categories in turn.

There is a further step in Kant’s argument. For, having shown (as he thinks) that experience conforms to the categories, he feels that he must show that the categories conform to experience. That is, they cannot denote mere abstractions, but must have their primary application in experience; and that means (as he argues at the very beginning of the
Critique)
in space and time. (Kant’s thesis in the first section—the Transcendental Aesthetic—is that space is the ‘form’ of ‘outer sense’, time is the ‘form’ of ‘inner sense’. This means, roughly, that the idea of experience is inseparable from that of time, and the idea of an experienced
world
is inseparable from that of space.) In this way, he tries to show that the rationalist view of knowledge is as mistaken as the empiricist view. For rationalism assumes an understanding of such categories as cause and substance independently of any actual or possible experience to which they might be applied. Through the process of ‘fit’ between concept and experience, Kant argues, the whole of scientific knowledge is generated. And it is through examining the structure of this ‘fit’ that the synthetic
a priori
principles of the understanding may be expounded and justified. For example, if we are to understand how it is that the category of cause gains application in experience, we must see experience itself as already restricted by a general principle of causality, the principle that every event has a cause. By elaborating the system of ‘principles’ Kant hoped to establish that the fundamental axioms of science are synthetic
a priori.
In this, while he was partly influenced by the parochial conceptions of Newtonian physics and Euclidean geometry, he was also able to argue in abstraction from those sciences, and to deliver results which might well be accepted by many contemporary scientists. For example, Kant attempted to provide a proof of the unity of science (the theory of all events as falling under a law of mutual influence), of the necessity of a principle of conservation of ‘substance’ (mass for example, or energy), of the need for both intensive and extensive magnitudes in the formulation of scientific laws. All these proofs carry persuasive weight beyond the limitations implicit in eighteenth-century scientific thought.