The problem of personal identity centers around the question of what makes me, me. We tend to identify one another by our physical appearances or by our personalities and behavior. But my physical appearance changes (I don’t look much at all like I looked when I was five), and our behaviors and attitudes can change as well. So, what makes me, me?

Some suggest our memories are central to who we are— nobody else has my memories of passing my driver’s test or making the winning shot in a basketball game — such that these memories form the basis of my personal identity.

Imagine the following: while committing a bank robbery, I slip and bang my head on the curb. I wake in the hospital with no memory of the robbery. In fact, I have no memory of my previous life whatsoever. I can engage in the normal activities but my doctors conclude I do indeed (I’m not faking it) lack all recall of my life before the accident. I am not expected to recover any old memories.

The question is this: am I guilty -- not legally speaking, but metaphysically speaking -- of the crime? That is, is the amnesiac in the hospital bed the same individual who committed the crime? If so, what exactly is it that makes me the same person over time?