1 July 1997
Thanks for your letter of 22 June, with your thoughts on unit4 of The Ultimate Nature of Things...
Are you struggling with subjectivism? It was his 'robust sense of reality' i.e. believability which led Russell, or so he claimed, to reject Meinong's theory (which he had advocated in his early Principles of Mathematics) that everything that can be referred to, including round squares, must have 'being' in some sense. It must be admitted that the theory he was rejecting sounds pretty whacky. However, Russell's appeal to the 'robust realism' of common sense is a million miles away from the reality principle. It cannot be emphasised enough that in metaphysics one cannot be guided by gut reactions like these. If you can't 'believe', then at least try to imagine.
All this applies to your criticisms of Lewis' possible world theory, of course. My objection to the theory is not, 'Where are all these other spaces and times then?' That kind of question (or, rather, begging of the question) cuts no ice. Lewis has just said: 'Where?' and 'When?' are questions that relate meaningfully only to our space and our time. My objection is rather that the reality of now, of our being here or my being here cannot be accommodated on Lewis' ultra-realist view. If possible worlds are 'real' as Lewis says, then the claim I am leading up to is that there must be alternative perspectives, alternative ways of comprehending reality, one of which displays our world as the unique actual world, while the other perspective reduces all possible worlds including this world to the same ontological level.
I liked Wittgenstein's On Certainty. Contemporary philosophers working in epistemology would do well to study that book. But I must stress that the pursuit of 'actuality' has nothing to do with the problem of scepticism, in the epistemological sense; even though they both lead the sense datum theory! Descartes is the key here. Worrying whether I might not wake up the next minute on a laboratory bench is epistemological scepticism. Worrying about the relation between what objectively exists and this... is a problem of metaphysics. Descartes is asking both questions at the same time: that is one of the things that gives the inquiry undertaken in the Meditations such depth.
On Kant's 'Refutation of Idealism': The important thing here is that, despite what he says, Kant is not arguing against Berkeleian immaterialism. (Don't be surprised that Kant misunderstood Berkeley: misunderstanding each other is something that philosophers do all the time, and the 'great' philosophers do most frequently.) 'Dogmatic idealism' the target of his attack is the theory I call naive or 'unrefined' subjectivism; a far cry from Berkeley. The naive subjectivist makes the fundamental error of thinking that one could have a coherent notion of a 'subject' or 'self' without a correlative notion of 'world'. If there is nothing to judge or say but how things subjectively are, then there is nothing to judge or say, period. You can't piece together a self that makes judgements without the notion of correct/ incorrect memory. But the notion of correct or incorrect memory presupposes an account of personal identity or continuity, which in turn presupposes a theory of a world within which the continuing self is located.
The theory of phenomena and noumena is a very different kind of 'rejection of idealism'. Here Kant is rejecting Berkeley, but his reason for doing so is that while Berkeley rightly recognises the necessity of a distinction between our perceptions and what those perceptions are ultimately of (for Berkeley, the mental 'archetypes' or blueprint in the mind of God) where Berkeley goes wrong is in supposing that we can have positive knowledge of such 'things in themselves'. For Kant, noumena are not 'material' or 'mental': we cannot know what they are (or what it is: as Schopenhauer later pointed out, even talk of number is unjustified here).
The difficulty reading the Critique of Pure Reason is partly accounted for by the fact that it was patched together in six months, then hastily revised for the second edition. Apparently, German philosophy students prefer the English translation by N.K. Smith to the German original, with its page long sentences!
You don't like noumena: then why not be a simple materialist or, failing that, a mind-body dualist? One thing I am trying to show is that it is not quite so easy as one might think to be either of those two things.