I turn now to the question of upper time limits for legally permissible abortion practice, the main regulatory question in which I believe most people are interested. Should there be an absolute cut-off for abortion? And if so, when should that be? Disappointingly, my arguments in Parts I and II do not provide a definitive answer to this question. I argued that the constitutive traits of personhood emerge gradually in human beings, but that there is nonetheless good reason to recognize the value in growing human embodiment, including in the womb, and that, as a matter of moral necessity, personhood must be regarded as all or nothing past a minimum threshold. I also argued that there are compelling reasons to recognize birth as that threshold past which the moral status of humans is full and absolute. But a range of absolute cut-off points for abortion could be consistent with these claims. Here, then, I will focus only on what my arguments do clearly suggest on the matter of upper limits, both in terms of the kinds of constraints they place on legal cut-off points and criticisms of abortion law which they might be used to counter.
The ubiquitous ‘arbitrariness’ complaint against any absolute cut-off is one criticism which, by now, we should be able to dismiss fairly quickly. Whether it is the absolute upper limit or the ‘working gestational limit’ (such as the twenty-four- week limit under the Abortion Act 1967) that is in question, this ‘arbitrariness’ complaint against legal line-drawing is not a sustainable criticism of any threshold where the arbitrariness impugned is that of the sorites kind. Not only does that complaint neglect the fact that resolution by clear stipulation is a function of the law, it also implies something about the nature of personhood which I argued there was little reason to believe, and good reason to disbelieve. It implies that the beginning of personhood is a sharp borderline, or, what I called the ‘punctualist’ thesis. I argued that, particularly given the falsity of punctualism, the inability to nonarbitrarily distinguish a twenty-four-week fetus from a fetus at twenty-three weeks and six days is not a reason to lower an abortion limit.
It is clearly incumbent on the law to stipulate a threshold of fully recognized personhood. I argued that birth is a particularly appropriate threshold for the law to use, owing to the significance of separate embodiment in the world for everything it means to be a person. Birth also has the legal virtues of clarity and recognizability. It has a universal social salience, high visibility, and unmistakability that make it especially suitable as a legal boundary-line. The birth threshold is not susceptible to reckless or negligent errors or accidents, and hence also does not encourage the kind of defensive or cautionary practices by healthcare professionals that might threaten to scale back abortion access far behind the permissions of the law were the threshold to be placed somewhere in gestation. Birth is not a matter of speculation, diagnosis, or disagreement. Settling on birth as an absolute cut-off allows for no ignorance of the upper limit, especially given the widespread cultural use of birth as an unequivocal marker of fully realized personhood outside of the law. Although there is still widespread disagreement about the fetus, it is universally understood that newborns are members of the human community, and, indeed, they are immediately treated as such: they are washed, wrapped up, embraced, and (usually) named, all within minutes of emerging from the womb. The extra-legal significance of birth is an added virtue of birth as a legal cut-off, since it leaves scant room for ambiguity, confusion, or ignorance.
But stipulating birth as the threshold for legal personhood status is not inconsistent with drawing an upper limit on abortion sometime before birth. Neither British nor American law recognizes the personhood of the early human being before it is born. But even if it is not equated with homicide, some might think there are compelling reasons to protect the life of the late fetus with an upper limit on abortions performed in late pregnancy in all but perhaps the most dire circumstances. The argument for an upper limit might be bolstered by the fluidity of human development and the close resemblance of late fetuses and neonates. It is not wholly unacceptable, on my account, to impose near-absolute cut-off some time before birth. The question, again, is simply what that upper limit would need to be like. First and foremost, it must be administrable. It is a rule of law requirement that there be a clear and practicable boundary-line for abortion, a boundary that is completely perceptible, that is enforceable, that treats like cases alike, that is supported by reason to the extent that it is within the range of reasonable cut-off points, and that there is no conclusive reason against adopting. This said, is not incumbent on lawmakers to provide reasons why the threshold is preferable to its closest neighbouring points. Not only is this obligation in tension with the aim of practical resolution as an end in itself, it falsely assumes that there exists, either biologically or morally, a non-arbitrary threshold of the kind.