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Brain in a vat argument for scepticism


To: Eric G.
From: Geoffrey Klempner
Subject: Brain in a vat argument for scepticism
Date: 8 February 2007 09:46

Dear Eric,

Thank you for your email of 29 January, with your University of London essay in response to the question, ''I cannot prove that I am not a brain in a vat. Therefore I do not know anything about the external world.' Discuss.'

This is an excellent piece of work. You report the arguments accurately and express reservations in the right places. Imagining myself as someone coming new to this subject, I feel that I would obtain a good grasp of at least one of the central issues from reading your essay.

Work of this quality in an exam would tend to be pushing for a first. What will make the difference is your ability to articulate your worries, reservations in a clear and meaningful way.

I often have the problem of UoL students sending me essays which do not respond to the actual question, paying particular attention to the way that it is worded. This is really the most important aspect of exam technique. Many of the questions are designed to get you thinking on your feet, upsetting students who have memorised standard essays (something which I never recommend).

In this essay, you have stuck to the question, so there can be no objection on that score. However, an examiner might well be disappointed that you have pushed the issues raised by Putnam to one side as being 'beyond the scope of this essay'. They are patently not beyond the scope of an answer to the question set. Therefore, you should say something about them. You don't have to give equal billing to Putnam and Nozick, you are allowed to some extent to pick and choose the arguments that most grip or interest you, but the examiner wants to know that you fully appreciate the relevance of Putnam's arguments to this question.

I would raise a different point. You express uneasiness about the externalist move, and I think that there is some justification for this. It just seems odd, or at least unconvincing, to offer a 'refutation' of scepticism about knowledge based on a redefinition of 'knowledge'. Intuitively, it is very disturbing to consider the BIV or evil demon scenario. It seems paradoxical to claim that this feeling is merely based on a fallacy or wrong understanding of knowledge.

What is needed is an examination of the concept of knowledge, not in terms of 'necessary and sufficient conditions' but rather in terms of *the point* of having a concept of 'knowledge' in our vocabulary.

It is not obvious (to me) that when an individual considers what is or may be the case, the term 'knowledge' has any contribution to make. Outside, it is snowing. I am concerned with whether the snow will get so bad that the traffic will get snarled up on the way home and I will end up being stuck in a bus for three hours, or face the alternative of walking two miles uphill through snowdrifts. So I switch on local radio, which is giving regular updates on the weather situation. I might or might not be convinced that the information is reliable, but either way my question is not, 'Do I KNOW that the snow will not continue through the day at the present rate?' but simply, 'WILL the snow continue or not?'

Needless to say, the question whether I might be a brain in a vat is completely irrelevant to this. Sceptical doubts are empty when no real practical consequences hang on the outcome.

When, if ever, do we ask ourselves, 'Do I know...?'? I would say, outside the philosophy class room, never.

However, as soon as one moves to the third-person standpoint then there is a very real and practical point in raising questions about what other people 'know'. Primarily, this is because of our interest in the reliability of testimony, and assessing who is or is not to be relied on for information on a given topic. So while, 'Do I know?' is rare, 'Does he know?' is common. When I say, 'My wife knows that the snow will continue,' there are two judgements, the judgement I made on the basis of the radio report and a judgement based on considerations of a broadly Nozickian kind. She heard the radio broadcast too, or saw the BBC weather on TV.

In other words, a complete answer to this question would not only outline the externalist objections to the BIV argument, but would also offer some kind of attempted justification for an externalist approach, heading off the worry that we have escaped the sceptical argument by 'changing the subject' and defining knowledge to be something other than what it in fact is, or what we intuitively take it to be.

All the best,