> Is it really living if you don't have anything worth dying for?

Biologically--of course, as gremlinn answered. But I doubt you meant it that way. Is it really a life worth living? Of course not. If one did not value anything so highly that he would die for it, that would imply that he valued his life above all else. It's a purity of selfishness that I doubt many people can muster without years of practice. To actually live that way would be extraordinarily miserable, not only for psychological, social, and spiritual reasons but even for simple physical reasons: extending one's life at all costs requires an almost joyless existence.

-Gabe