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Epistemology and Descartes' methodological doubt


To: Sean K.
From: Geoffrey Klempner
Subject: Epistemology and Descartes' methodological doubt
Date: 19th November 2008 12:43

Dear Sean,

Thank you for your email of 10 November, with your essay for the University of London Diploma entitled, 'Descartes' Methodological Doubt'.

This is an excellent essay, which offers an insightful reading of Descartes' strategy in his First Meditation, together with hints and pointers towards Descartes' use of 'methodological doubt' in his overall strategy of constructing a foundationalist epistemology.

I have no real criticisms of your exposition. It is for the most part accurate and fair.

However, as to why Descartes starts off relatively easily by considering reasons for doubting one's perceptions because sometimes our perceptions are false, I do think that more can be said than that this is merely a heuristic or rhetorical device, or even a strategy for softening up the reader.

One might think: why not just cut to the chase and start off with the dreaming or evil demon hypotheses? why waste time considering reasons for doubt which are less than persuasive? Admittedly, this is what philosophers often do. You give an argument to the effect, 'You might think that...' and then you counter it, before going on to give an argument which stands up to objections.

I take it that the main issue here -- a point which you make, although the point might have been made even more strongly -- is the idea of the existence of the subjective world of the mind, as a fully autonomous realm. We need this idea in order to raise Descartes' question about the existence of an external world. But why should we believe in it in the first place?

Before he gets to the cogito, Descartes has to convince the reader that a 'perception' is *never* what it seems, a direct link to the object perceived. Objects and 'perceptions' belong to two distinct realities. What shows this, initially, is the argument from illusion. If 'seeing' a tree involved somehow a direct relation between myself and the tree, then how could misperception occur? The very same experience, Descartes argues, obtains when I see a 'round tower' which is round, and when I see a 'round tower' which is square. By the logical law of identity, the object of 'I see...' cannot be the tower itself. It must be the perception, on the basis of which I form the judgement, 'There is a round tower over there,' a judgement which is true or false depending on objective fact.

A critic would argue that that is the 'decisive move in the conjuring trick', after which everything else is easy. We have fully bought the idea that we 'see' our own perceptions, not the things themselves. Dreams are a vivid example of how perceptions and things can mismatch. And so on.

Thus, once the reader reaches the 'cogito', they are already three quarters convinced. Descartes doesn't simply come out and say, 'I seem to see an 'I' therefore there is an I.' He says, when I seem to feel F, there is necessarily an F feeling, when I seem to judge, there is a judging; in general, every mental act is given incorrigibly as an item of direct inner awareness. Finally, what could these items belong to, but an 'I'?

There is one point where you link the evil demon with contemporary hypotheses like the brain in a vat. This is inaccurate, as applied to Descartes, because the point here is that we haven't got space. A brain in a vat, or a computer running the Descartes program, is an object in space. The evil demon hypothesis is the hypothesis of a reality of experiences caused by an entity which is not spatial, a world where space as such does not exist in any form other than as a subjective 'perception'.

There are other issues one could discuss: You are right about the profound effect of the idea that Descartes' thinking processes are themselves 'controlled' by an outside entity. Here, one could go into the difference between interacting with a virtual reality as an autonomous agent (e.g. Neo in his pod in the Matrix) and only 'thinking' you are autonomous when in reality your mental actions are themselves controlled. In the latter case, it would be like watching a movie of one's own life rather than living it. But is that hypothesis so much as conceivable? What would it mean to exist merely as a 'puppet' controlled from outside, so that every mental act is not 'mine' but that of another? In that case, is there anything left to serve the function of an 'I'?

Another issue, which relates to the question of God's 'benevolence' is the wider one of our faith in our capacity to reason to the 'best explanation'. Why should reality match up to our standards of best explanation? This is perhaps one example of a question which transcends the Cartesian foundationalist assumption of a world of incorrigible 'givens', and still has relevance today. One answer given is that of 'naturalized epistemology' (cf. Quine) and the idea that there is an empirical explanation -- e.g. based on the theory of evolution -- of why we are so good at constructing explanations. At this point, epistemology leaves behind the Cartesian world of 'first philosophy' and becomes continuous with science.

All the best,