Does not Descartes beg the question when he argues "I think therefore I exist?" My problem with Descartes' argument arises from his attempt to treat "existence" as a predicate that can be applied to subjects. When he says "I think", the word "I" will have a referent if and only if I exist. So, if the proposition "I think" is meaningful -that is, if it succeeds in attributing the property of thinking to a subject "I"-, it is trivial that I exist. However, in order for the proposition "I think" to be meaningful, I must exist in the first place. So, Descartes seems to beg the question of "my" existence. One might just as well assert, "I dance the funky chicken therefore I exist" or my favorite "I outgrabe therefore I exist" (a reference to Lewis Carroll). Thanks...