To: Charles C.
From: Geoffrey Klempner
Subject: Descartes Meditation 1: the case for universal doubt
Date: 25 May 2007 10:11

Dear Stephen,

Thank you for your email of 20 May, with your University of London Diploma Essay in response to the question, 'In his First Meditation, how does Descartes attempt to show that there is reason to doubt everything one believes?'

A lot of thought has gone into this essay and it is a good piece of work. On this basis, I am confident that you will do well in this module if you continue in this way.

First, about the title. You are right, there is no excuse for misreading the question. However, in the present case it would have been possible to make exactly the same point whether the question used 'his' or 'ones'.

Suppose I wrote an essay, explaining why I have come to doubt most of what I believe. In my teens, I joined the Moonies. Then I spent a couple of years with the Scientologists. When I saw David Icke on TV I was convinced that he is right about the Illuminati, and so on. I could make a pretty convincing case. But it would not convince you to entertain similar doubts, unless you made the exceedingly dubious judgement calls that I made.

By contrast, when Descartes talks about all his former beliefs, he is not alluding to his Jesuit education or to any aspect of his personal history or psychology. He expects the reader to nod in assent. This is a special 'voice' in philosophy which appears also in St Augustine and Montaigne. In speaking apparently for himself he is building a case which demands assent from anybody.

The difference between expressing personal belief and making a case extends in particular to the issue of God, which seems to have caused you a bit of trouble. Descartes makes it clear that one must prepared to consider the possibility that there is no God but instead an evil demon (more on that in a moment). His own personal belief is that there is a God. Even though he may drop hints about this, these are irrelevant to the case he is making. (Later in the Meditations, he goes on to attempt two proofs of the existence of God, clearly acknowledging that so far as his project of building secure foundations for knowledge is concerned, this is something which requires proof.)

In discussing the point that we are sometimes deceived in what we think we perceive, and again when you talk about the inevitability of human error, you miss a point that Descartes was keenly aware of. As he says, we are only aware of our errors in perception because of the possibility of taking a closer look. The round tower may look square in the distance, but we have no difficulty in general in telling apart things that are square and round. No-one seriously entertains the possibility that they can't tell a round tower from a square one when they are standing ten feet away.

The argument that we sometimes make mistakes and errors, therefore we can never be sure in any case whether we are making an error is weak and unconvincing. So long as the basic principles which we rely on in building up our knowledge are sound, we can take errors in our stride. That is why Descartes crafts his argument as an attack on those basic principles.

The two fundamental principles are that experience has something to teach us about objective reality, and we have the capacity to reason about what we perceive. The principle about experience is smashed when one considers, not the fact that we never seem able to tell whether we are awake or dreaming - which as you point out is far from being the case with actual dreams - but rather that what we are given in a dream is essentially the same as what we are given when we perceive, viz. subjective experience. Subjective experience taken as such does not carry on its 'face' any objective meaning. We have to give it that.

This point is forced home with the thought experiment of the evil demon. Not even my belief that there is such a thing as space or spatio-temporal objects (which still exist in a Matrix scenario) can withstand the counter-hypothesis that my experience of seeming to perceive objects in space is caused directly by an evil demon with Godlike powers.

The principle that we have the capacity to reason about what we perceive is similarly undermined by the evil demon hypothesis.

But what about the evil demon? Isn't Descartes still assuming something, viz. that there is such a thing as objective reality, that there is more to reality than just my subjective experience? I think he is. For the purposes of his project of building foundations for knowledge this assumption - effectively, the rejection of the solipsist view that 'the world is my world' - is acceptable. There is an objective story. That goes without saying. We have beliefs about what that story is, which talk about a world of objects and other people and God. But those beliefs cannot be knowledge, so long as we lack a firm grip on the foundational principles upon which those beliefs are constructed.

All the best,

Geoffrey