I can come up with a rough definition, but rough definitions fail in exactly those cases where there is potential disagreement.

Eh, functioning is a very rough definition and we've got to that pretty quickly.

So will we rather say that we include mentally disabled humans above a certain level of functioning? The problem then is that babies almost certainly fall well below that threshold, wherever you might set it.

Well, the question is whether food animals fall beneath the level of babies. If they do, then I can keep eating them happily enough; if they don't, I've got the dilemma as to whether to stop eating animals or start eating babies.

And it's not clear to me, without knowing what you mean by functioning, that pigs or cows are more intelligent than babies. I've not seen one do anything like that. Predatory animals - wolves and the like, on the other tentacle, are obviously more intelligent than a baby.

As to how I'd resolve the dilemma if it did occur, I'm leaning more towards stopping eating food animals than starting to eat babies. Despite the fact that food animals are really tasty, I don't want to put a precedent in place that might get me eaten at some point.

I assume you've granted that sufficiently advanced AIs ought to be counted as people.

By fiat - sufficiently advanced for what? But I suppose I'll grant any AI that can pass the Turing test qualifies, yes.

Am I killing a person if I terminate this script before compilation completes? That is, does "software which will compile and run an AI" belong to the "people" or the "not people" group?

That depends on the nature of the script. If it's just performing some relatively simple task over and over, then I'm inclined to agree that it belongs in the not people group. If it is itself as smart as, say, a wolf, then I'm inclined to think it belongs in the people group.

Really? It seems to me that someone did invent the taboo[1] on, say, slavery.

I suppose, what I really mean to say is they're taboos because that taboo has some desirable effect on society.

The point I'm trying to make here is that if you started with your current set of rules minus the rule about "don't rape people" (not to say your hypothetical morals view it as acceptable, merely undecided), I think you could quite naturally come to conclude that rape was wrong. But it seems to me that this would not be the case if instead you left out the rule about "don't kill babies".

It seems to me that babies are quite valuable, and became so as their survival probability went up. In the olden days infanticide was relatively common - as was death in childbirth. People had a far more casual attitude towards the whole thing.

But as the survival probability went up the investment people made, and were expected to make, in individual children went up - and when that happened infanticide became a sign of maladaptive behaviour.

Though I doubt they'd have put it in these terms: People recognised a poor gambling strategy and wondered what was wrong with the person.

And I think it would be the same in any advanced society.