| The implicit assumption is: Vx [x thinks > x exists]. You also seem to think that Descartes needs to provide an accont of what it means to exist. Why think that? You speak English. 'Exists' is a perfectly intelligible English word. And so we can understand the conclusion and the explicit assumption. Of course, it is an interesting philosophical question as to what existence amounts to. Quite a hard one. But it's a different philosophical question. You seem to be criticising Descartes for not answering that question, but that's just to conflate distinct issues. It's also a little incoherent to say that philosophy is useless because it ignores certain questions, which then turn out on inspection to be further philosophical questions. And philosophers do grapple with what existence amounts to. Go read some Quine if you're actually interested. In fact, Quine provides an account of existence which vindicates teh implicit premise I've outlined above. But Quine is writing 400 years after Descartes, after the great philosophical revolution brought about by the logical developmenets of the philosopher Frege (which incidentially had an impact on computing and so on). So we might say that Descartes doesn't answer the questions you raise fully. But only someone a little up their own arse would criticise Descartes for failing to deal with questions it took 400 years of philosophical, logical and mathematical development to make substantive progress on. |