I agree that the merits of any given social contract can be debated and shouldn't be taken as intrinsically ok, so I don't think I want to be relativistic in that sense. But if there is to exist a social contract at all (which I do think is a good thing), there has to be a way of removing people from it who can't uphold it, and perhaps helping them to get to a position where they can, if possible. (Ideally I think incarceration etc would be more about rehabilitation than anything else; in practice I don't think this is true at all, at least not where I live. That's somewhat beside the point, though.) And if the social contract includes capital punishment (which I don't support), then maybe that's not a good social contract, but it provides you with some rationale at least for executing people. Not for banning abortion, though, unless you see getting pregnant as a violation of the social contract --- which we don't. So I don't think you can regard them as equivalent.
I intended to cover taxation in my second paragraph, but the draft and duty to rescue are certainly more interesting examples in this context. I'm not that fond of the draft, either, but that may be an unsustainably idealistic position. As for duty to rescue, doesn't that have a clause about not having to endanger oneself? If so, it's not a particularly heavy imposition on autonomy.
I'm familiar with the violinist scenario but I definitely perceive it as supporting abortion; I'd find it morally abhorrent to argue that the kidnapped person should be forced to continue providing lifesupport. Do you think they should?
(Thanks for the discussion, incidentally!)
Not for banning abortion, though, unless you see getting pregnant as a violation of the social contract --- which we don't.
But where is this claim 'it is not a violation of the social contract' coming from? You say the social contract does not define what is moral, so presumably the social contract here matters as reflecting a consensus that something is moral or immoral - so now we need to justify the consensus. Buck-passing has to stop somewhere, and in abortion debates that's usually going to come back to personhood.
...As for duty to rescue, doesn't t
A few years ago, I wrote a little dialogue I imagined between 2 materialists, one of whom was for and one against abortion, centering on the personal identity question. I recently cleaned it up and added a number of references for the biological claims.
You can read it at An Abortion Dialogue.
Early feedback from #lesswrong is that it's a 'nicely enjoyable read' and 'quite good'. I hope everyone likes it, even if it doesn't exactly break new philosophical ground.