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Is Descartes guilty of circular reasoning?


To: Christine W.
From: Geoffrey Klempner
Subject: Is Descartes guilty of circular reasoning?
Date: 16th October 2009 10:35

Dear Christine,

Thank you for your email of 12 October, with your essay for the University of London Modern Philosophy Descartes et. al. module, entitled, 'Is Descartes Guilty of Circular Reasoning?'

I am responding somewhat quicker than I would normally, as I am expecting a surge of essays as my new students start sending their work.

This is in many ways a model essay. I liked the way you analysed Descartes' argument from 'I exist' to 'The C&D (clear and distinct) rule is guaranteed', via his proof of God from the idea of perfection. This is something I try to get my students to do when the are faced with an argument like this. As a rule, if you can find extra premisses or steps (even if these are not explicit in the text) this can often greatly increase one's understanding of the argument in question, as well as helping to identify its weak points.

The first point I would make, which applies to all the work you send me, is that I would like you to respond to a specific examination question. 'The Cartesian Circle' is a topic which appears regularly in examinations, which means that it is a great temptation to write your 'model essay' then reproduce it in an examination when the question comes up. However, you will find that examination questions often have a twist or a dink; if you can address the specific question, exactly as it is worded, rather than just write on the topic this will impress examiners, who are looking for students who can show that they are 'quick on their feet'. The examiners want to you work in the examination, not just reproduce stuff from memory.

Another point which is a potential criticism of your answer is that there is no evidence that you have looked at discussions in the literature on Descartes dealing with the Cartesian Circle. Again, this is a general point, this time about the Modern Philosophy paper and other papers relating to the history of philosophy. You are required to show a thorough knowledge of the primary texts, but you are also expected to do your own research on the contemporary discussions relating to the philosopher in question.

As you admit, at around 1500 words this is rather shorter than the target length I would like you to aim at, 2000-2500 words. Yes, your answer is concise, and there is very little I would disagree with. However, if you find that you are running out of things to say then you need to dig deeper, do more research.

To get to specifics, one thing that your answer strongly suggests is that Descartes recognizes two 'tiers' of subjectively necessary truth: Truths which appear 'clear and distinct' but require God's guarantee in order for him to be able to conclude that they are true, and truths whose clarity and distinctness is such that they could not be false, regardless of whether God exists or not. In the latter category is the Cogito. Even if he is being deceived by an evil demon, Descartes knows that he exists.

You also put the case for the plausibility of the idea (one cannot say more than that) that the steps in the argument for God's existence have the kind of clarity and distinctness which the Cogito has; or, to put this more explicitly, an evil demon could not trick Descartes into thinking he has an idea of God when he hasn't.

It is worth remembering at this point that in Meditation 1 Descartes has already discarded a possibility which would threaten the entire foundational enterprise, namely, the thought that 'maybe I am mad'. If I cannot rely on my own sanity, my capacity to reason, then there is no point in going further. Similarly, when one considers the evil demon hypothesis in the light of the idea of God, to persist with doubt is simply mad, it is not something that a rational person can think. Descartes is asking the reader to *see* this for themselves.

I am not claiming that this line of reasoning is valid; only that it suggests a possible interpretation which avoids the Cartesian Circle objection, in a way which does not seem merely arbitrary.

You claim to have identified another case of circular reasoning, in the Cogito itself. One of the criticisms made of the Cogito is that Descartes is not justified in moving from the observation, 'I think, I exist is true whenever the thought presents it to my mind' to 'I exist as a temporally extended substance'. It would be perfectly possible for an evil demon to have created my consciousness ten second ago, along with all my apparent memories, and possible also that I will cease to exist in ten seconds time.

However, if we just consider the argument from the idea of perfection, does Descartes need the stronger claim? Why can't he say that 'I exist as a temporally extended thinking substance' is a justified inference, given that there exists a God who would not deceive me?

All the best,