Descartes famously argued that the one undoubtable truth is that when he is thinking he exists. This idea, I think therefore I am, is clear and distinct, which are the marks of self-evident necessary truths. Descartes’ idea still has a lot of pull, but isn’t there an obvious kind of counter-example to it?
Couldn’t it be the case that the Evil Demon has multiple personality disorder and that I (or you) am a figment of this fragmented consciousness? Couldn’t it be the case that the Evil Demon has made me up in the telling of some story to ease his boredom? Or maybe the Evil Demon is a Solipsist. In reality He is the only thing that exists and all of us are just a backdrop his all-powerful mind has concocted…It would then be the case that I wonder whether I exist and yet I do not exist…aren’t these kinds of things counter-examples to the Cogito?
One response that might be made is that, while it is the case that I do not technically exist as I thought I did (as a mind-independent entity), I still exist (as a fictional mind-dependant entity). So, I still exist, just not in the way that I thought I did. This would allow us to keep the general truth that whenever there is some thinking there has to be a thinker (it would just be the Evil Demon himself who is actually doing the thinking), but it does seem to do violence to clearness and distinctness as a criterion of self-evident necessary truths.
Does anyone know if this kind of objection is ever dealt with by Descartes or any of his objectors/commentators?