Another email in response to this post:
You wrote something a long time ago that has stuck with me. I can’t find it but I think it was during a stem-cell debate. It was something like: If we didn’t have motives for deciding that human embryos were not human beings, if we were disinterested, it would be obvious that they are. It’s only because we have reasons for wanting to make them expendable that we pretend it’s a mystery.
Thanks! That was a good point that past-me made. (I can’t find it either, but I’m sure others have made it too.) And to restate the point, we would not have any difficulty in figuring out when the life of a human organism began.