There are many reasons I don't support the death penalty, but the primary reason -- the overwhelming reason -- is that I'm a skeptic. It's the same reason I'm an atheist, actually. I base my entire existence on the constant awareness that no matter how sure I am of a thing, I could be wrong. The death penalty is the only penalty for which there is no "undo" button. We can let wrongfully accused people out of prison. We cannot bring the dead back to life.