Pro-life nation, take 2

An alert reader sends this article from the the March 24 issue of Commonweal (free registration required) about a disagreement between two pro-life philosophers:

. . .for about two weeks after fertilization, that embryo may split, resulting in identical twins. Less commonly, two embryos may combine, resulting in one individual. As Ramsey notes, “there is fluidity and indeterminacy in either direction during the earliest days following conception.” So how do we think about the various entities involved in twinning and combination?

An interesting question, on which people of good will can disagree. Paul Ramsey (1913-88), a pioneer in the field of bioethics, thought it plausible:

that an individuated human life does not begin until the possibility for twinning and combination has passed, a stage called restriction, about two weeks after fertilization. Assuming Ramsey was right, what does that mean for research on human embryos that destroys them in the process? If the embryos have not reached the stage of restriction, such research would not count as homicide, because it wouldn’t involve killing a human being.

If it’s not homicide, is such research morally permissible? Perhaps, given its potential benefits. But not necessarily.

And does this have an impact on the use of the "morning after pill"? We suggest you read the entire article.