To: Tony B.
From: Geoffrey Klempner
Subject: Why is the objective reality of the world in doubt?
Date: 2 April 2001 12:54

Dear Tony,

Thank you for your e-mail of 25 March, with your piece for the Associate Award, 'Why is the objective reality of the world in doubt?'

I like the way your argument is clearly laid out. Thank goodness it isn't 'Tractarian'! It is succinct and to the point. - I can't remember if I told you that for my B.Phil thesis at Oxford, which is normally 30,000 words, I submitted a thesis of 11,000 words which had been composed on slips of paper two inches wide. (I know that Wittgenstein used to cut his notebooks up into 'Zettel', keeping the bits he thought worth keeping and discarding the rest, but I don't think he ever used this method to compose a work from scratch.) I used to go around Oxford with the sheaf of slips held together by a bulldog clip and sit in coffee bars shuffling them, occasionally putting in a word here, a comma there! I have never been tempted to repeat the experiment, but I believe it was well worth making.)

I do not accept that you have succeeded in demonstrating that 'the objective common view described in §1 is not just doubtful, but either quite meaningless or reduces to solipsism.' I am talking about the argument you actually give. I am not denying that there might be an argument to be had in this area. (In 'Naive Metaphysics', and also in the Pathways Metaphysics program, I try to present a case for anti-materialism. My case against turns ultimately on considerations related to pragmatism and the alleged primacy of physical agency.)

Let me first state what I take to be Berkeley's line of thought. *If* it makes sense, as Descartes believed, to hypothesize that it might be the case that my perceptions are produced, not by objects in a material world, in which I exist as an embodied subject, but by an X (whatever X might be) which possesses mental but no material existence, *then* we ought logically to deny that any sense can be given to the notion of a 'material world'. In other words, if reference to space and matter is not an essential part of the very description of the world as I experience it, but merely a hypothesis put forward as one possible explanation for my experience, then according to the empiricist principle of significance the very idea of 'matter occupying space' is without content. For a hypothesis has significance, according to the empiricist principle, only if the condition under which it would be true can be specified in terms of experience.

Laid out in this way, it is clear what the strategy for the materialist should be. Deny that it makes sense to conceive of a purely mental reality.

A crucial, unexpressed step in the above argument is the argument from illusion. According to the argument from illusion, the immediate object of my awareness, when I perceive a tomato (to use the famous example of H.H. Price) cannot be the tomato itself, because I could be enjoying the very same experience even though no tomato was there, for example, if I were hallucinating. On its own, however, that step does not get you to where you want to go. This is a point I've made before about the difference between the 'evil demon' and the 'evil scientist' scenarios. In contemplating the evil scientist or brain in a vat scenario, we grant the possibility that the way things are in the material world may be radically different from the way we perceive it. In contemplating the evil demon scenario, we grant the possibility that there may be no such thing as a 'material world'.

What reason can be given for accepting the more radical hypothesis? None that you have given. The crucial step 6. in your argument happens all too quickly!

All the other things you say, rebutting the objection to the evil demon hypothesis on the grounds of its 'absurdity', or 'improbability', or on the basis of the 'scientific account of perception' are exactly what a Berkeleian should say. But this is all after the decisive move has been made. And a critic will simply deny your right to make that move.

There are a couple of books which have been on my desk for quite a while now, which I have not mentioned because I have been meaning to read them. One is Mark Sacks 'The World We Found: The Limits of Ontological Talk' (Duckworth 1989) and the other is A.W. Moore 'Points of View' OUP 1997. I really should have read Adrian Moore's book because I knew him at Oxford, and the book was given to me to review! (Moore lists 'Naive Metaphysics' in his bibliography.) From a survey of Sacks book, it seems very much a book you should try to see, if you can, dealing with issues relating to Kant, Strawson and transcendental idealism. Moore's covers some of the same ground, but particularly in relation to Nagelian themes.

If you can get hold of these works then that will provide me with a powerful motivation to read them!

All the best,

Geoffrey