To: Kathleen C.
From: Geoffrey Klempner
Subject: Kant's refutation of idealism
Date: 26 January 2006 12:42

Dear Kay,

Thank you for your email of 15 January, with your second essay for the Metaphysics program, in response to the question, 'Give a careful account of Kant's second 'Refutation of Idealism'.'

You have given an accurate, concise account which closely follows the text of Kant's argument, but also expands on the crucial points.

At the end of your essay, you recognize that there is an issue concerning - as I would put it - whether Kant has in fact proved the existence of something independently 'real' existing outside me, or merely described the parameters to which any possible experiences must conform.

Any possible experiences must be experiences 'as of' a world of objects existing outside of me. What this means, as you explain in your essay, is that the objects I perceive have a certain 'permanency', or 'the ability to move about so providing different perceptions'. In effect, what the argument shows to be necessary for 'the... empirically determined consciousness of my own existence' is my belief in a theory which describes an arrangement of moving or stationary objects in space, a theory which I am able to continually test against my perceptions.

There is no way to talk about experiences except as houses, trees, the sky etc. Unlike, say, a scientific theory, the 'theory' of space and time is located at the root level of perception, there is no theory-free way to describe the data upon which the theory is based.

Perhaps you can see why some commentators, notably P.F. Strawson, have taken the view that noumena are completely dispensable, in fact, otiose. The notion that when I look out of my window, all I see is a 'merely phenomenal reality' only has weight so long as I am contrasting 'phenomenal' with something that exists beyond the phenomena. In the absence of such a contrast, there is simply empirical reality, just as Kant claims.

In that case it really would be the case that the conclusion of Kant's Refutation of idealism is that my mere consciousness of my own existence proves the 'real existence' of objects outside of me, in the only sense of 'real' that I am able to understand. Hence, Wittgenstein's observation that 'a nothing would serve as well as a something about nothing can be said,' which Strawson fully endorses, far from showing that 'we seem not to have left the idealist far behind' demonstrates (in Strawson's view) quite the opposite.

I do heartily recommend P.F. Strawson 'The Bounds of Sense' which is one of the best books ever written on Kant, even though ultimately I disagree with Strawson.

Why do I disagree? The short answer is that Kant's refutation of idealism is available to the 'transcendental subjectivist'. Kant was aware of the existence of a crucial gap in the argument, a gap which he plugged with the notion of noumena.

This is not apparent in the text of the Critique of Pure Reason. All that Kant offers in the way of argument for noumena is 'there cannot be appearances without something that appears'. In Kant's vision (one may surmise) transcendental subjectivism is not even considered as an option, despite the fact that it would be consistent with the Refutation of Idealism. He is thinking of a plurality of subjects, each of whose experiences meet the conditions described. But there is no coherent way to describe how this plurality can exist without leaving the phenomenal world and ascending to the noumenal level. Your experience, as such, does not appear in the world of my possible experience.

The alternative way of plugging the gap, as we know, is Wittgenstein's private language argument. This is the crucial possibility that Kant missed.

In writing your account of Kant's argument, you might have considered the other things that Kant's says in this section, before and after he gives the argument itself. For example, he says that his argument is directed against the 'problematic idealist' such as Descartes, directly answering Descartes' question about the 'cogito'. If I know that I exist, then I know that the world outside me exists also. Kant dismisses the 'dogmatic idealist' as not worthy of serious consideration.

My view is that is in fact not an accurate representation of what Kant's argument achieves. It does refute the 'dogmatic subjectivist' (naive subjectivist or egocentrist). It does not refute either the 'problematic idealist' or the 'dogmatic idealist'. You can't use the Refutation of Idealism to disprove the hypothesis that we live in a Matrix world, or even the evil demon hypothesis. (Kant admits as much when he discusses the question of dreams.) Nor can you use it to disprove Berkeley's idealism. It is worth thinking about what would be sufficient to refute either of these two 'theories'.

All the best,

Geoffrey