Immanuel Kant (1724-1804) is one of the most influential of ‘modern’ philosophers, covering a lot of ground in an impeccably fine-tuned and systematic manner. Offering any kind of summary of his works in a thousand or so words is impossible, so I may err on the side of profligacy on this occasion. But I’m assisted as ever by commentaries. Particularly helpful in this instance are Roger Scruton’s writings on Kant. I was taught philosophy by him briefly at Birkbeck College in 1971 before I switched to the study of sociology. He was an accomplished philosopher, especially on aesthetics, for all that he morphed into an apologist for outdated forms of conservatism. So here goes.
Kant owed much initially to Leibniz but came to be challenged in particular by David Hume’s radical scepticism. Thus provoked, he set out to develop a systematic critique of human thought and reason. His aim was establish the nature and limits of knowledge. As Scruton notes, he wanted to devise a metaphysics that exposed the very foundations of discursive thought. He wanted to show that:
- there is a legitimate employment of understanding, the rules of which can be laid bare, and that limits can be set to this legitimate employment (he went on to conclude that rational theology is not just unbelievable, but unthinkable).
- Hume’s scepticism is impossible since the rules of understanding are sufficient to establish the existence of an objective world obedient to a law of causal connection.
- certain fundamental principles of science – for example, that every event has a cause, that objects exist in space and time – can be established a priori.
For anyone unfamiliar with the terms ‘a priori’ denotes knowledge gained through reason alone, independently of sensory experience; while ‘a posteriori’ denotes knowledge gained from empirical evidence acquired through observation and sensory experience of the physical world.
Kant’s proof of (i) to (iii) begins with his theory of ‘synthetic a priori’ knowledge. Scientific knowledge, he asserted, is ‘a posteriori’ – in other words, it arises from and is based in actual experience. Science deal with matters of fact. But science rests on certain universal maxims and principles which, because their truth is presupposed at the start of any empirical enquiry, cannot themselves be the outcome of such an enquiry. These maxims/principles are therefore ‘a priori’. Some of them are ‘analytic’ (that is, true by virtue of the meanings of the words used to formulate them), others are ‘synthetic’ (that is, say something substantial about the empirical world). Moreover, these synthetic a priori truths, since they cannot be established empirically, are justifiable, if at all, via reflection; and reflection will confer on them the only kind of truth that is ‘within its gift’, namely, ‘necessary truth’. Such truths form the proper subject matter of metaphysics.
Knowledge for Kant is achieved through a synthesis of concept and experience: he called this synthesis ‘transcendental’. 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. He argued that neither the empiricist nor the rationalist can provide a coherent theory of knowledge.
Kant also postulated a single subjective unity of self. After all, I immediately know of my present mental states that they are mine. He referred to the ‘Transcendental Unity of Apperception’ (transcendental because the unity of self is presupposed in all self-knowledge). Thus the unity of self is a totality over and above the totality of its mental states. But while there is an area of self-knowledge which is subjective, one can always be mistaken, for example about the past. Therefore the self as subject presupposes the self as object. This gives the lie to radical scepticism, which can only be stated from the premise of self-knowledge.
This ‘Transcendental Deduction’ establishes the validity of a general concept of objectivity. But there is more to say. Kant contends that all knowledge involves the application of concepts to experience. He wrote here of a ‘theory of categories’. One cannot think in terms of objects without thinking of entities that endure through change; and this requires one to apply to one’s experience the concept of ‘substance’. Scruton writes:
‘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.’
Having satisfied himself that experience conforms to the categories, he then sought to show that the categories conform to experience: that is, they don’t merely denote abstractions but have their primary application in experience, namely, in space and time. Time, he argued, is the ‘form’ of the ‘inner sense’, while space is the ‘form’ of the ‘outer sense’. What does this mean? He seemed to be saying that the idea of experience is inseparable from that of time, and the idea of an experienced world is inseparable from that of space. He was attempting to show that the rationalist view of knowledge is as mistaken as the empiricist view. Rationalism assumes an understanding of categories like substance and cause which is independent of any actual or possible experience to which they might be applied. However, 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 fundamental axions of science must be seen as ‘synthetic a priori’. Why Kant called this a form of ‘transcendental idealism’ remains much debated.
There is space enough for an equally truncated precis of Kant’s discussion of ethics. Once more, Hume’s scepticism was in his firing line. ‘Theoretical reason’ guides belief and ‘practical reason’ guides action. The first, properly used, Kant called ‘understanding’, and when improperly used ‘pure reason’. Reason can be properly used, but it must then be subjected to those determinations which transform it into practical reason. To clarify, understanding issues in judgements which might be true of false. Practical reason issues in imperatives which might be acted upon but which cannot be called true. Practical reason consists in the justification of imperatives; and the challenge therefore is to define and validate a concept of objectivity which will both apply to such imperatives and generate a recognisable system of morality.
Imperatives are of two kinds, the ‘hypothetical’ and the ‘categorical’. Hypothetical imperatives are those with conditional antecedents – ‘if’ … referring to some condition, need or desire. They provide reasons for action only to the person who has the condition, need or desire mentioned in the antecedent. Categorical imperatives contain no ‘if’ antecedents. They assume the form of ‘do this’, or ‘you ought to do this’. They claim, in short, a genuine objectivity, independent of theoretical reason. Kant’s formulations include: ‘Act so as to will the maxim of your action as a universal law in a ‘Kingdom of Ends’.’ Two principles are at work here. The first is that in the ideal of the Kingdom of Ends what is, ought to be and what ought to be, is. As Scruton puts it (if in sexist terminology):
‘in positing such a realm, and himself as part of it, the agent sees himself in relation to other rational beings as one among many, of equal importance to them, deserving and giving respect on the basis of reason alone, and not on the basis of those empirical conditions which create distinctions between men.’
The second principle implies that rational beings are constrained by reason not to bend others to their own purposes. These two principles constitute the central Kantian idea that moral law is founded in, and expressive of, the ‘respect for persons’.
How is the categorical imperative to be defended? No moral law, indeed no practical reasoning, is intelligible without the postulation of freedom. And the free agent is distinguished by the constraint imposed by reason. Freedom is subjection to the moral law. Scruton again:
‘It seems … said Kant, that I know myself in two ways, theoretically, as part of nature, and practically, as agent. And bound up with these two forms of knowledge are two forms of law which I discover through them: the laws of nature and the laws of freedom, the latter being … the categorical imperative.’
In theoretical knowledge, Kant went on to contend, we know ourselves as ‘phenomena’, in practical knowledge we know ourselves as ‘noumena’. The world of noumena is here understood to be open to reason, but solely in relation to practical reason.
This is of course no more than a snapshot, a dip into an elaborately argued system of throught.
References
Scruton,R (1981) A Short History of Modern Philosophy. London; Routledge and Kegan Paul.
Scruton,R (1982) Kant. Oxford; Open University Press.