Persons and Human Beings
But we may be getting ahead of ourselves already. It might be asked what the category ‘person’ even means in the context ofthis discussion, especially in relation to the separate category ‘human being’. Most moral philosophers distinguish these two classifications.
The ascription ‘human being’ is taken to be a biological category, encompassing any living creature that is genetically a member of the human species. Any human fetus, or, for that matter, newly formed zygote, is at least a human being in the bare sense that it is an individually identifiable human life. It is definitely not a frog, or a cat.
The ascription ‘person’, on the other hand, denotes a category of beings which possess a certain kind of moral status, typically elaborated in terms of interests or rights, and yielding a cluster of normative implications concerning how it is morally acceptable to treat such beings. Precisely what all of these normative implications are is a matter of some dispute. At the very least, however, personhood status is taken to entail strict rules about the permissibility of killing the bearers of that status. It is never permissible to kill persons, no matter how painlessly, for reasons of convenience or (on most views) even to promote an appreciable level of welfare among other creatures or persons. The same kind of strict prohibitions on killing are not generally believed to apply to non-persons. The normative classification captured by the term ‘person’ has, in different places, been expressed in terms of ‘moral status’, ‘metaphysical status’, or, in Mary Anne Warren’s description, humanity ‘in the moral sense’.3 As I see it, all these terms grasp at more or less the same notion. To ask whether a fetus is any of these things is simply to ask whether it is something that, by virtue of its essence or attributes, is akin to fully matured human beings in the thing that endows them with their special status, interests, and rights.
The analytical distinctness of human beings and persons is apparent from the fact that we can at least conceive of non-human persons. Intelligent aliens, angels, and perhaps even some non-human animals could all fit our concept of a person without being biologically human. So ‘human being’ and ‘person’ do not mean the same thing. It may be true, nevertheless, that all human beings are, necessarily, persons. This would be so if all members of the human species also happened to meet the conditions for personhood, making overlap between the categories 100 per cent. The analytical separateness of the two just means that it is an open, and, hence, an intelligible question whether or not this is so.
Having noted this important distinction, let us turn to the prima facie case for placing the question of prenatal personhood at the forefront of our ethical and legal investigations about abortion. For many, that case is clear and simple. Our moral norms prohibit the intentional killing of other persons in all but the most exceptional circumstances. Without adequate justification or excuse, such killing is legally classified as murder. If a fetus is a person, then, abortion is, on the face of it, in the same moral category. At best, defensible homicide. At worst, murder. This sets the stakes high when it comes to the moral status of the fetus. Perhaps even the real possibility that a fetus is a person, morally on a par with you and me, is enough to alter the whole structure of the abortion debate. That possibility might prompt us to ask whether abortion could perhaps be subsumed into a moral or legal category ofjustified homicide, or to think about whether abortion is correctly analysed as an instance of intentional killing.
It should be acknowledged at this point that not everyone engaged in discussion about abortion concedes that the embryo or fetus is a human being, where
Mary Anne Warren, ‘On the Moral and Legal Status ofAbortion’ (1973) 57(1) The Monist 43—61.
‘human being’ is taken to mean ‘full member of the human species’ rather than a form of human life, or human biological material. As can also be true of other animal species, one might argue that there is a difference between what counts as human biological material and what counts as an individual member of the human species. A cow fetus is certainly a cow in one sense, that is, it is bovine, but perhaps it is not yet an identifiable instance of a cow.
Some philosophers have appealed to the consensus among embryologists when asserting that a new, individual human being is present by the end of conception, when a zygote possessing a complete set of human DNA comes to exist. However, the degree of developmental completeness that is required before a life form may count as a new member of the human species is an evaluative question, not a scientific one. No embryological facts can tell us whether a single-celled zygote properly counts as a whole member of the human species (albeit an immature one), rather than as biological material that is the precursor to a new member, since the idea of a full and complete member of a species is not itself strictly scientific. Returning to the cow example above, a group of zoologists might agree about every biological fact concerning cows and yet disagree about whether a cow embryo should be considered a complete species member.
So the fact that human beings begin to exist at conception is by no means a given, depending on what precisely is meant by that designation. I will say nothing further about this issue, however. The distinction between human beings, a biological category, and persons, a moral and evaluative one, is a sufficient primer for my arguments throughout this book without any need to challenge the claim that embryos and fetuses are human beings. In everything that follows, therefore, I am willing to concede that human beings begin to exist at conception.
-  See Robert P George and Christopher Tollefsen, Embryo: A Defense of Human Life (Doubleday2008) chapter 5, citing Bruce Carlson, Human Embryology and Developmental Embryology (CV Mosby2004) 58 and Keith L Moore and TVN Persaud, The Developing Human (7th edn, WB Saunders 2003)40; Patrick Lee, Abortion and Unborn Human Life (1st edn, The Catholic University of America Press1996) chapter 3; Christopher Kaczor, The Ethics of Abortion (1st edn, Routledge 2011) 127—9. Othershave attacked the proposition that all zygotes and embryos count as individual human beings on theground that an entirely individualized human being doesn’t emerge until some days or weeks after conception, either because some parts of the early embryo (or ‘blastocyst’) eventually become the placenta,or because monozygotic twinning is still possible before the ‘primitive streak’ (the earliest precursor ofthe spinal cord) is formed at fourteen days (see: Mary Warnock, An Intelligent Person's Guide to Ethics(Overlook 2004) 65—6; Ronald Green, The Human Embryo Research Debates: Bioethics in the Vortexof Controversy (Oxford University Press 2001) 31; and Joseph Donceel, ‘Immediate Animation andDelayed Hominization’ (1970) 31 Theological Studies 76, 98—9).