[Wil]

But once we're wiped out, that doesn't matter anyway. I must say I'm edging on agreeing with Jacob and Bullet Magnet. I haven't got myself a donor card or given blood precisely because, as an environmentalist, I don't think helping more and more humans to exist is a good thing (and also the National Blood Service are prejudgemental morons).

But on the other hand, what you call looking at the long term I would identify as a slippery slope argument. You're talking of time scales we can't accurately predict. Besides, not preventing human death now doesn't actually address the rising birth rates. We should tackle the problem at the source instead of just raising these imperfect levées around the flood.

p.s. To address the question, I agree that putting embryos above living humans is silly and designed to appeal to popularity.