After reading the entire debate this comment spawned... if the goal is to determine whether we should support abortion legalization and fewer restrictions (possibly up to infanticide? (!)), or perhaps support more heavy regulation, it seems like arguing over whether an action is reactive, proactive, etc can't possibly have any relevance, and seems like a particularly virtuist way of looking at things.
Are we not solely interested in consequences? What are our values and how do we maximize them? Clearly saying we value "human life" isn't enough, and we need to be more narrow. What do we actually value? If we say we value all potential humans, should we be spending all of our time impregnating women, being pregnant, or researching how to shorten pregnancy and/or grow humans in a test tube? If we draw the line in what we value somewhere else, do we end up with post-pregnancy abortions? Is that okay? I feel like there are real questions, and the reason those questions are interesting is because we can't just take the copout answer of "proactive actions bad, acts of omission okay" because consequentialism won't let us.
Are we not solely interested in consequences?
What you mean we, consequentialist?
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.