I've made a lot of mistakes in my mind

The writers of Ghost in the Shell really could have skipped all the animated robot nudity and phoned-in plot, and boiled that film down to a very thought-provoking introductory philosophy lecture.

It got me thinking, though, that's the point. If you replace every constituent part of a human being one by one, do you still have a human being? And is it the same human being? You don't need cybernetic implants to face that paradox, though; all the cells in my body die and regenerate at regular intervals, and even they are composed of circulating molecules that are broken, reordered, replaced, recirculated constantly within and among the cells.

As far as anyone can prove, I am a chemical process between trillions of organic molecules, regulated by a self-replicating chemical "program". Under an electron microscope, you can't see the forest for the trees; but that's because a forest is just a word we use to describe a whole lot of trees all together.

If I am only the sum of my constituent parts, then the oldest part of me is seven years old; and what am I, if not a thief, a usurper? My infant body has been dead for fifteen years, flushed out piece-by-piece and excreted by a different sort of body, which was gradually rejected and destroyed by another, and another, and then I killed that one and here I am.

My memories of being fifteen, or eleven, or five, then, are just the ghosts of those dethroned kings, haunting me on the periphery of my thoughts. I didn't do any of that; I stole it from the old and dying neurons I replaced. And when this body dies, you won't notice; but will I? And will I haunt the new possessor of my identity with vague memories of "his" ill-spent twenties?

I reject all these suppositions, but it's a good thing to scare yourself with before bed. A scientist from the 1700s, knowing nothing about radio waves or satellites, might empirically examine a cellular phone in the middle of a call and determine it to be a sentient thing, as he could find no external source for its intelligence. The only evidence he would have against this hypothesis would be the voice's own insistence. Likewise, I believe I am more than just an elaborate, self-amplifying chemical reaction; but my own insistence is all I have to go on.

--Kevin