Quote Originally Posted by FoxyGrandma3000 View Post
"I think, therefore I am."

That is the currently accepted argument for your own existence.

From Wikipedia: "The very act of doubting one's own existence arguably serves as proof of the reality of one's own existence, or at least of one's thought."

So please don't use that argument again!
That word 'arguably' in the wikipedia quote you posted is there for a reason: it's okay to argue the point. And plenty of philosophers have done so - you'll find some examples under the Criticism section on that same wikipedia page.

(Though I don't think PostScript99 actually was arguing against his own existence, just questioning the nature of that existence - cogito ergo sum doesn't apply. But that aside.)

Cogito ergo sum's a great argument, but it's not some sacred truth set in stone, it's not meant to discourage people from questioning.