Sure, as I said, it's interesting that's how these analogies work — by inviting the reader to (for the sake of argument, of course!) zero out almost all of the salient real-world information about the act. They move us further from the real-world scenario and toward increasingly abstract contemplations of possible combinations of rights and obligations.
That's a wide-open invitation for bias — an invitation for each reader to pick and focus on whichever analogy fits their prejudices, instead of more closely examining the facts ... and in particular any facts that may be available about who chooses abortion, why they do that, and what the consequences of that choice are.
To me this suggests that using these analogies is likely to lead to worse decisions — policy decisions and personal decisions.
We want to figure out a head of time what we should do in morally ambiguous situations. An easy way to find discrepancies in our ethical framework is to invent thought experiments where some particular aspect of a scenario is made arbitrarily large or small. Would you kill a person to save two people? why? would you kill a person to save 200 people? why? what about killing a billion people to save two billion? If we actually have values which we'd actually like to maximize in the world around us, slight differences in the specific details of these values m...
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.