The Incorrigibility of the Cogito

Abstract

There is a kind of sceptic who thinks that there is absolutely no proposition whatsoever that anybody knows. Such a sceptic is very likely to think that it is always possible that our cognitive capacities should lead us astray. Afortiori, he must hold (if he is logical) that it is always logically possible that our cognitive capacities should lead us astray. And it may be that this sceptic thinks it is because it is always logically possible for our cognitive capacities to lead us astray that there is absolutely no proposition that anyone knows. (It does not much matter for the purposes of the subsequent argument whether any sceptic actually has held the views I have just mentioned.) I think some philosophers have supposed that Descartes has refuted the view of the sceptic that it is always logically possible for our cognitive capacities to lead us into error. If Descartes is right, there are at least three beliefs, and perhaps more, which are such that it is not even logically possible for our cognitive capacities to have led us astray when we arrive at them. If I believe (i) that I exist, or believe (ii) that I believe something, or believe (iii) that I am mentally modified in some way or other that is not specified, what I believe must be true. Bernard Williams, in his book: Descartes: The Project of Pure Enquiry, puts this by saying that there is a class of logically incorrigible propositions. I think he, and I think Descartes also, thinks that it follows that there are some propositions which some people-i.e., anyone at all who believes these propositions, know to be true. However, I do not wish to get involved in questions about what either Descartes (or Williams) actually thought on these matters. What I wish to consider is whether there are any logically incorrigible propositions and whether it follows that, if there are, these propositions are known to be true by any person believing them. I doubt whether the word 'incorrigible' is a good one. One speaks of people as being incorrigibly wicked but not, except jokingly, as being incorrigibly good. Analogously, though one can have opinions which are incorrigibly false, one cannot have opinions