for this position by comparing the right to life with the right to vote: “If children are allowed to develop normally they will have a right to vote; that does not show that they now have a right to vote” (1995). According to this position, it is true that we once were embryos and fetuses, but in the embryonic and fetal stages of our lives we were not yet valuable in the special way that would qualify us as having a right to life. We acquired that special kind of value and the right to life that comes with it at some point after we came into existence.
We can begin to see the error in this view by considering Thomson’s comparison of the right to life with the right to vote. Thomson fails to advert to the fact that some rights vary with respect to place, circumstances, maturity, ability, and other factors, while other rights do not. We recognize that one’s right to life does not vary with place, as does one’s right to vote. One may have the right to vote in Switzerland, but not in Mexico. Moreover, some rights and entitlements accrue to individuals only at certain times, or in certain places or situations, and others do not. But to have the right to life is to have moral status at all; to have the right to life, in other words, is to be the sort of entity that can have rights or entitlements to begin with. And so it is to be expected that this right would differ in some fundamental ways from other rights, such as a right to vote.
In particular, it is reasonable to suppose (and we give reasons for this in the next few paragraphs) that having moral status at all, as opposed to having a right to perform a specific action in a specific situation, follows from an entity’s being the type of thing (or substantial entity) it is. And so, just as one’s right to life does not come and go with one’s location or situation, so it does not accrue to someone in virtue of an acquired (i.e., accidental) property, capacity, skill, or disposition. Rather, this right belongs to a human being at all times that he or she exists, not just during certain stages of his or her existence, or in certain circumstances, or in virtue of additional, accidental attributes.
Our position is that we human beings have the special kind of value that makes us subjects of rights in virtue of what we are, not in virtue of some attribute that we acquire some time after we have come to be. Obviously, defenders of abortion cannot maintain that the accidental attribute required to have the special kind of value we ascribe to “persons” (additional to being a human individual) is an actual behavior. They of course do not wish to exclude from personhood people who are asleep or in reversible comas. So, the additional attribute will have to be a capacity or potentiality of some sort.3 Thus, they will have to concede that sleeping or reversibly comatose human beings will be persons because they have the potentiality or capacity for higher mental functions.
But human embryos and fetuses also possess, albeit in radical form, a capacity or potentiality for such mental functions; human beings possess this radical capacity in virtue of the kind of entity they are, and possess it by coming into being as that kind of entity (viz., a being with a rational nature). Human embryos and fetuses cannot of course immediately exercise these capacities. Still, they are related to these capacities differently from, say, how a canine or feline embryo is. They are the kind of being – a natural kind, members of a biological species – which, if not prevented by extrinsic causes, in due course develops by active self‐development to the point at which capacities initially possessed in root form become immediately exercisable. (Of course, the capacities in question become immediately exercisable only some months or years after the child’s birth.) Each human being comes into existence possessing the internal resources and active disposition to develop the immediately exercisable capacity for higher mental functions. Only the adverse effects on them of other causes will prevent this development.
So, we must distinguish two sorts of capacity or potentiality for higher mental functions that a substantial entity might possess: first, an immediately (or nearly immediately) exercisable capacity to engage in higher mental functions; second, a basic, natural capacity to develop oneself to the point where one does perform such actions. But on what basis can one require the first sort of potentiality – as do proponents of the position under review in this section – which is an accidental attribute, and not just the second? There are three decisive reasons against supposing that the first sort of potentiality is required to qualify an entity as a bearer of the right to life.
First, the developing human being does not reach a level of maturity at which he or she performs a type of mental act that other animals do not perform – even animals such as dogs and cats – until at least several months after birth. A six‐week old baby lacks the immediately (or nearly immediately) exercisable capacity to perform characteristically human mental functions. So, if full moral respect were due only to those who possess a nearly immediately exercisable capacity for characteristically human mental functions, it would follow that six‐week old infants do not deserve full moral respect. If abortion were morally acceptable on the grounds that the human embryo or fetus lacks such a capacity for characteristically human mental functions, then one would be logically committed to the view that, subject to parental approval, human infants could be disposed of as well.
Second, the difference between these two types of capacity is merely a difference between stages along a continuum. The proximate or nearly immediately exercisable capacity for mental functions is only the development of an underlying potentiality that the human being possesses simply by virtue of the kind of entity it is. The capacities for reasoning, deliberating, and making choices are gradually developed, or brought towards maturation, through gestation, childhood, adolescence, and so on. But the difference between a being that deserves full moral respect and a being that does not (and can therefore legitimately be disposed of as a means of benefiting others) cannot consist only in the fact that, while both have some feature, one has more of it than the other. A mere quantitative difference (having more or less of the same feature, such as the development of a basic natural capacity) cannot by itself be a justificatory basis for treating different entities in radically different ways. Between the ovum and the approaching thousands of sperm, on the one hand, and the embryonic human being, on the other hand, there is a clear difference in kind. But between the embryonic human being and that same human being at any later stage of its maturation, there is only a difference in degree.
Note that there is a fundamental difference (as we showed above) between the gametes (the sperm and the ovum), on the one hand, and the human embryo and fetus, on the other. When a human being comes to be, a substantial entity that is identical with the entity that will later reason, make free choices, and so on, begins to exist. So, those who propose an accidental characteristic as qualifying an entity as a bearer of the right to life (or as a “person” or being with “moral worth”) are ignoring a radical difference among groups of beings, and instead fastening onto a mere quantitative difference as the basis for treating different groups in radically different ways. In other words, there are beings a, b, c, d, e, etc. And between a’s and b’s on the one hand and c’s, d’s and e’s on the other hand, there is a fundamental difference, a difference in kind not just in degree. But proponents of the position that being a person is an accidental characteristic ignore that difference and pick out a mere difference in degree between, say, d’s and e’s, and make that the basis for radically different types of treatment. That violates the most basic canons of justice.
Third, being a whole human being (whether immature or not) is an either/or matter – a thing either is or is not a whole human being. But the acquired qualities that could be proposed as criteria for personhood come in varying and continuous degrees: there is an infinite number of degrees of the development of the basic natural capacities for self‐consciousness, intelligence, or rationality. So, if human beings were worthy of full moral respect (as subjects of rights) only because of such qualities, and not in virtue of the kind of being they are, then, since such qualities come in varying degrees, no account could be given of why basic rights are not possessed by human beings in varying degrees. The proposition that all human beings are created equal would be relegated to the status of a superstition. For example, if developed self‐consciousness bestowed rights, then, since some people are
