Wired’s Sarah Zhang has written a short article purporting to show that science cannot determine “when life begins.” But the article itself begins in a muddle about the concepts of life and personhood that makes its efforts hopeless. It is certainly true that science cannot tell us whether a human being deserves legal protection, or under what circumstances it deserves it. And if we define “personhood” as the status of deserving such protection, it follows that science cannot tell us when personhood begins.
Science is, however, capable of telling us that after fertilization creates a human embryo, that embryo is living rather than dead or inanimate, human rather than a member of a different species, and an organism rather than a cell or tissue of another organism. None of the issues Zhang raises—that fertilization takes time, or that many of the embryos formed by implantation fail to implant in the womb, or that they do not have brainwaves until later—change, or could change, that conclusion. There are people who argue (not, I think, well) that living human organisms don’t deserve legal protection until they have brainwaves: but it’s unquestionably living human organisms about which they’re talking.
Again, though, it is true that science cannot resolve the moral question. It cannot rule out the possibility that we should regard some living human organisms as human “non-persons” or “un-persons.” If we shudder at that concept, it’s not because of scientific knowledge.