Tuesday, August 2, 2011

Kant's refutation of idealism

To: Jason I.
From: Geoffrey Klempner
Subject: Kant's refutation of idealism
Date: 9 February 2004 13:53

Dear Jason,

Thank you for your e-mail of 1 February, with your second essay for the Metaphysics program, 'Kant's Refutation of Idealism'.

The original question was, 'Give a careful account of the argument of Kant's second 'Refutation of Idealism.'

You are right to focus on what the Refutation of Idealism adds to what has gone before. However, you don't say much about this except at the beginning, where you contrast Kant's response to the 'dogmatic idealism' Berkeley with his response to the 'problematic idealism' of Descartes, and right at the end, where you contrast the claim that the existence of objects in space 'is presupposed a priori a necessary condition of determination of experience' (B278) with the claim made previously in the Analytic that objects exist 'a priori as a necessary condition' of experience.

One question which occurs to me is, Is Kant right about his own argument? Does it require or presuppose the previous demonstration of the incoherence of a Berkeleian theory according to which 'the very existence of an unthinking being consists in being perceived'? I am not so sure about this, having looked in vain through the transcendental aesthetic transcendental deduction for a convincing argument against Berkeley. What one does find is the claim that *if* one held a particular view of space (that space is a 'thing in itself') *then* you would inevitably end up in Berkeley's position. However, on the face of it that is not a refutation of Berkeley, merely a hypothetical explanation of where Berkeley goes wrong. It seems perfectly possible for Berkeley to respond, 'I made no such assumption!'

But let's stay with Kant. One might argue along the following lines. There are two questions to settle: the ontological question of whether we can so much as conceive of objects existing unperceived in space; and the epistemological question of whether I can know anything about these objects.

According to Kant, Descartes assumes that I have indubitable knowledge of my own subjective states, raising the question whether I can know anything about how things are in the external world. (Actually, Kant is wrong about this - Descartes was prepared to consider the possibility that there is no 'external world', that all my experiences are produced directly in me by an evil demon. Substitute 'God' for the evil demon and you have Berkeley's theory.)

One possible claim would be that *if* I cannot know, e.g. that I am sitting at a desk looking through the window at the trees outside, *then* I cannot know anything about my subjective states. Knowing 'about' my subjective states is knowing how they are determined (not in the sense of cause and effect but rather in the sense of the medieval proposition 'all determination is negation' - 'determined' means having this quality rather than that). Suppose I remember going for a walk yesterday. One question is whether I actually did go for a walk yesterday. But another question is whether I did actually have the *experience* of going for a walk yesterday. On this view, what Kant's argument in the Refutation of Idealism has shown is that I cannot have this knowledge of what I experienced yesterday, *if* I cannot have knowledge of things that actually happened in the external world yesterday, like my going for a walk.

Has he shown this? And so what if he has?

The reason for the second question is that the sceptic might be happy to give up belief that I can know anything about the 'determination' of my subjective experiences. If the sceptic says, 'I admit I know nothing, other than the content of the present moment' then Kant has no response.

Has Kant shown that self-knowledge presupposes knowledge of external objects? There are two issues here, one about the nature and order of my experiences, and the other about the time which they take. From what Kant actually says in the Refutation of Idealism, it looks as though one could argue that all that I lose, in being prepared to entertain scepticism about the external world, is the possibility of comparing my sense of subjective time with objective time. My Sunday walk seemed to go very quickly, while it took ages to wash the dishes after Sunday dinner. Assuming that I am really a prisoner of the evil demon and neither of these things really happened, there is no investigation I can undertake which will decide whether my impression of the relative duration of these two events corresponds to the truth or not. But that is not giving up very much.

It would be far more impressive if Kant could show that there is no way I can know that I experienced the walking or the dishwashing scenarios, if I cannot have knowledge of the external world.

I am happy that Kant is in a position to show this. What I am not so sure about is whether is can be derived from what he actually says in the Refutation of Idealism. I am confident, however, that Kant would agree with the argument which I give in the program as a refutation of the 'subjectivist' view (which neither the historical Berkeley nor Descartes held) according which envisages a solitary subject making judgements ('this is red, this is blue...' etc.) about an uninterpreted stream of subjective experiences.

All the best,

Geoffrey

(Factual note: my conscience requires that I own up to the fact that I did not, in fact, wash the dishes or go for a walk. I did go out to my office and I did, as it happens, prepare Sunday dinner.)