In my opinion, the author of “Science and abortion” has missed the point by opting to “talk about personhood later” in favour of a discussion of the “scientific method” and “human life.”
I really don’t think that it’s at all contentious that an embryo is “a life” in the sense of being alive — that is, a scientifically observable biological entity that is growing, subsists on nutrients and water, exists from the point of fertilization etc.
Pro-choicers would be wasting their time to champion any scientific evidence to the contrary, and so they don’t; the science is simply not in contention. What is contentious, however, is when the embryo becomes a person in the legal sense, having its own rights and entitlements, separate and apart from those of its mother. The mother, we know with certainty, is fully entitled to all the rights and protections of other distinct persons under the law. This has not been established in the case of foetuses, and whether a foetus ought to be afforded such rights is a matter best left to philosophical, moral or legal debate, not the scientific method. As such, the author’s discussion of “scientific” vs “subjective” truth is totally missing the point, and therefore utterly unconvincing.
The whole article without the cuts might show some insight to why I focused on science for my discussion: http://umscl.wordpress.com/2012/04/03/commentary-science-and-abortion/