Is the self all that can be known to exist?

[Edwardo Piet]

I'm saying the self isn't the only thing we know exists because we also know that everything is what it is even if we were not to exist. And, in fact, we can't even know our own existence without knowing that. We can't have knowledge of self-identity without knowledge of identity. "I think therefore I am" presupposes "I think=I think" and "I am=I am".