Vagueness and Redundancy
The foregoing suggests that there is a very strong case for thinking that argument about abortion must start, first and foremost, with the question of fetal personhood. But what about Dworkin’s deep scepticism concerning that question’s propensity to produce principled, reasoned argument? Is the personhood question ultimately, as Dworkin suspected, an argumentative black hole?
As was seen, Dworkin believed that the personhood question is altogether unfruitful for abortion argument because neither side can appeal to a fact or an argument which the other must accept. Whatever new is learned or argued about the fetus, it is always open to discussants to maintain that it still does or does not fit their concept of a person.
Some have argued that stalemate in argument about personhood is down to the fact that personhood is conceptually vague. The philosopher Jane English claimed that vagueness in the concept of a person means that any attempt to solve the abortion problem using that concept is to ‘to clarify obscurum per obscurius’ ?8 It is nowhere near ‘sharp or decisive’ enough to do that work, she wrote. And if our concept of a person admits of no clear boundaries, we may well be at a loss when it comes to arguing the case of the fetus. English was particularly concerned with vagueness at the margins of the concept—in the penumbral region which, she claimed, the fetus occupies.
Of course, all of our classifications, including even the scientific ones, are vague at the margins. The concept of a person is not, in this respect, any more nebulous or less usable than many of our everyday concepts. English’s view of personhood as too vague to be of use in abortion argument was tied to her belief that it admits of no decisive set of necessary and sufficient conditions—it is, in her words, a ‘cluster concept’. This absence of sharp conditions is what produces contestable cases about which it is difficult to know what to say.
Of course, English was wrong if she believed everyone agrees that the fetus is a marginal case of a person. For many discussants on both sides, the fetus is far from a borderline case: it falls squarely within the parameters of personhood, or squarely outwith them. To be sure, these completely opposed viewpoints emanate from deeper disagreements about the core conditions of personhood, which English claimed are 
ambiguous. But it is disagreement about these core conditions (and in particular, about whether personhood supervenes on human species membership or psychological capacities) rather than vagueness at the margins of the concept which is responsible for the fetus being such a contested case.
Importantly, however, none of this entails that argument about personhood, including fetal personhood, is unreasoned or ungoverned by rules. For one, there are still some clear limits on what sensibly can or cannot be deemed a person—rocks are certainly not people, and normal, mature human beings certainly are. Perceiving those limits and extrapolating from them can be the first step in arguing intelligibly about the concept of a person. One would simply be wrong to think that there are no convictions about personhood that we share. There are. And addressing one another with arguments that build on those convictions is precisely how discussants manage to have principled exchanges about the conditions of moral status.
Dworkin’s own scepticism about the personhood question stemmed from his worry that no fact or argument could ever settle the matter once and for all, to the satisfaction of everyone. The problem, for him, was that disagreement about the conditions of personhood is interminable. One question is of course why this robs the personhood question of its ethical or legal salience. But one might also question the standards of inquiry Dworkin was insisting upon on pain of dismissing a disagreement as unreasoned. There are few, if any, ethical disagreements about which we would insist on the theoretical possibility of universal agreement or else dismiss the entire debate as irrational and unprincipled; certainly, no one dismisses disagreement about whether a practice is ‘just’ or ‘democratic’ on that ground. The standards of argumentation that Dworkin seemed to demand of the personhood debate are never met outside the realm of science, and are not always met within it.
At another point in his argument, Dworkin described the personhood question as ‘too ambiguous to be helpful’, for the reason that ‘it has a great many uses and senses that can easily be confused’. For example, he explained, we might suppose that zoologists one day discover that pigs are far more intelligent and emotionally complex than we have until now believed them to be. The question might then be asked whether pigs should now be regarded as persons in the philosophical sense. But Dworkin argued that there is in fact no need to decide whether pigs qualify for personhood in order to answer the more ‘practical’ questions that are really of interest to us, such as whether, in light of our new knowledge, we should now treat pigs in many ways as we treat human beings, acknowledging their right not to be killed for food or imprisoned in pens. These answers, he said, do not follow directly from any conclusion about the personhood of pigs, since:
We might believe philosophically that pigs are persons but that human beings have no reason to treat them as we treat one another; or, on the contrary, we may decide that pigs are not persons according to our best understanding of that complex concept but that nevertheless their capacities entitle them to the treatment persons give one another.40
40 ibid 23.
As he thought was true of the example, Dworkin suggested that it would therefore ‘be wise to set aside the question of whether the fetus is a person’ and focus instead on the key moral questions in which we are interested, such as whether the fetus is owed the right to life or whether its life should be regarded as sacred.
Was Dworkin right to think that the personhood question is merely a distraction from the moral questions that should interest us in abortion? Perhaps the distinction between persons and non-persons cannot, as he suggested, withstand the moral weight we load upon it.
It cannot be doubted that creatures lacking personhood status on our reckoning can still possess a moral standing that is highly significant, especially in some contexts. It is morally impermissible to torture cats or to kill them needlessly just so as with human beings, even if humans are persons and cats are not. Moreover, one might think that it is wrong to torture or needlessly kill cats for much the same reasons that it is wrong to do so to persons: that such actions interfere with the creatures’ interests in freedom from pain and in continued life. If it is possible to possess high moral standing without qualifying for personhood, it might be indeed wondered what really turns on personhood status. Why, it might be asked, can the answers to specific moral questions about the treatment of creatures not be answered without recourse to the person/non-person distinction?
These are important challenges. But I do not think they go to show that the personhood inquiry is wrongheaded or redundant in argument about abortion. There exists a shared idea about a class of beings that are endowed, by virtue of their essence or attributes, with the highest moral standing we accord, one equal to that of our own, and which goes hand in hand with certain inviolable rights. So far as the concept of a person has a fixed meaning among its users, this is surely it, and this part of its meaning is unaffected by disagreement about the constitutive properties of a person.
Insofar as the concept of a person is just a placeholder for a kind of being possessing the highest moral standing we accord, it is hard to see why talk of personhood need be confusing or distracting in abortion debate. ‘Person’ is a classification in common use, one that is readily comprehensible, universal, and is uncontroversial in its invocation of a ready-made package of protections and rights, especially the fundamental right to life.
It is consistent with this common understanding that it is morally wrong to treat non-persons in any number of ways, and quite possibly for reasons that mirror the wrongness of treating persons in similar ways (presumably, we must not torture cats for the same reasons that we must not torture persons). However, it is a core normative implication of personhood status that status bearers are automatically owed strong moral protection against being killed, including in circumstances in which non-persons could not claim that protection. This is particularly true of personhood in its legal sense, recognition of which triggers a catalogue of legal rights and protections, including the almost unqualified right to life. While other normative implications of personhood status may be the subject of greater debate (e.g.: does personhood status entail that the bearer cannot be the object of a proprietary transaction? Does it mean that she may not be treated merely as a means to an end?), ramifications concerning the permissibility of killing are present on any plausible account of what it means to be a person.
When elaborating personhood status in terms of these normative implications, we may still keep as an open question the possibility that the personhood category extends to some non-human animals not generally recognized as such. Such questions will, of course, arise out of discussion about what the constitutive features of a person are. But asking whether the human embryo or fetus in particular belongs in the special moral category which ‘person’ commonly denotes remains a key question for abortion argument whether or not the class of persons stretches to nonhumans as well.