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Quantitative Properties

Attacking the credibility of dualism is a somewhat surpising move by defenders of the conception threshold given the fact that, as I recounted, dualism is the only view about the nature of personhood that even appears to lend credence to the punctualist thesis, and hence, to the kind of arbitrariness critique of other personhood thresholds defenders of the conception threshold often put forward. If personhood is not an immaterial substance like a soul or an ego, but instead just supervenes on other physical or mental base properties, it ceases to be clear what reason anyone might have for suspecting that the beginning of personhood is an ‘existential pop’, rather than the gradual fading in of a quality. Whatever those base properties are believed to be, they certainly come into existence gradually, and this is as true of species membership as of anything else because of the progressive nature of conception. Unless some one is committed to the belief that persons begin when immaterial substances animate human material, what reason would he have to believe that they begin wholly and instantaneously? And if there is no good reason to accept punctualism, sorites-susceptibility will not be a legitimate critique of any theory of emerging personhood.

But George and Tollefsen may object that this misses the emphasis of their own argument. In fact, they state explicitly that to read their argument against all postconception thresholds of personhood as a form of sorites paradox is a misunderstanding.[1] They attribute this misunderstanding to Michael Sandel’s criticism of their position.17 Sandel suggests that their arbitrariness objection to post-conception thresholds of personhood mirrors the problem of the heap in which, we saw, someone is asked to specify which individual grain of sand makes the difference between a non-heap and a heapd8 Sandel rightly points out that the mere fact that the addition of one more grain cannot ever seem to make that difference does not mean that there is no difference between a grain and a heap, or that it is reasonable to say that the heap begins with the first grain of sand. By analogy, then, the continuity of human physiological and psychological development, and our inability to specify an exact threshold of personhood which is non-sorites-susceptible, are not a reason to hold that personhood begins at conception.

George and Tollefsen believe this misrepresents their argument. They write:

What the sorites analysis overlooks, however, is that we have specified a non-arbitrary difference in human development. For while it is true that there is no non-arbitrary difference between a blastocyst and a later embryo or infant, there is a non-arbitrary difference—a difference in kind—between male and female gametes and the single-celled human embryo. The embryo is a new human being—the same complete human organism, as Sandel himself seems to acknowledge, as the later child and adult. While subsequent changes exist on a continuum, the change from gametes to a new human individual does not. The union of gametes effects a substantial change that brings into being a new and distinct entity—in this case a human individual, a human being—in question.19

By claiming that they have specified a non-arbitrary point in human development, the authors seem themselves to miss part of the objection Sandel is raising. Sandel uses the sorites paradox to explain that, like in the problem of the heap, there is no reason to search for a beginning of personhood which is non-arbitrary in this particular sense—the sense of being non-arbitrarily distinguishable from its closest neighbouring points. There simply is no beginning of personhood which is distinguishable in this precise way, just as there is no sharp beginning of a heap of sand, unless, in the case of personhood, the punctualist thesis is true. Hence, the inability to specify such a point anywhere along the continuum of human development should not point in favour of the conception threshold.

Moreover, as we saw in the previous chapter, the claim that ‘the change from gametes to a new human individual’ does not exist on a continuum is false. The coming to be of a new human organism is a process, comprised of infinitely divisible successive points, none of which can be non-arbitrarily distinguished from their immediately adjacent points.

But George and Tollefsen might well interject here to charge me also with failing to understand the nature of their arbitrariness argument against all postconception thresholds of personhood. Perhaps their continuum problem is not at all as I describe it, and their sense of ‘arbitrary’ not the sorites sense that I am using.

The authors point out that qualities like consciousness and sentience exist on a spectrum in a way that the quality of ‘being a conceived human being’ does not. Late fetuses might well be conscious and sentient to a degree, but not enough to warrant personhood status, given a cognitive capacities-based view of personhood’s conditions. For that, conscious desires or rationality or self-awareness would be required on many accounts. Yet, as George and Tollefsen see it, the differences between these levels of mental functioning ‘is merely a difference between stages along a continuum’, stages which, moreover, may develop in the same creature gradually over time.20 Hence they describe such differences as merely ‘quantitative’, or differences in degree, which, they claim, cannot be the basis for treating creatures in different ways. Rather, moral rights, including the right to life, can only be possessed by a creature in virtue of the kind of being it is. ‘Human beings’, they say, ‘are intrinsically valuable and deserving of full moral respect in virtue of what they are’.2i

If George and Tollefsen are right in supporting the ‘animalist’ view that we are our human bodies, then it follows, for them, that all developmental changes subsequent to conception ‘exist on a continuum’ in a way that ‘the change from gametes to a new human individual does not’, even though it, too, comes about, like everything else, in non-arbitrarily distinguishable increments.22 The sorites problem here would be beside the point. It will not matter, on this argument, that the very coming-to-be of a new human organism is a continuous microphysical process

  • 19 George and Tollefsen (n 1) 123.
  • 20 ibid 119.
  • 2i ibid 123.
  • 22 ibid.

admitting of no non-sorites susceptible points. The argument is rather that we only possess moral rights in virtue of what we unchangeably are, that (according to animalism) what we are is human bodies, and that those bodies begin to exist, as individual organisms, at conception. Hence, the transition from gametes to zygote is non-arbitrary in a way that all subsequent changes are not, in that only it amounts to a ‘substantial change’—as they say, the kind of change ‘that brings into being a new and distinct entity, in this case, a human individual’^3 And it is only in virtue of being human individuals that we possess moral rights, since individuals can only possess such rights by dint of being the kind of things that they basically are.

I believe and hope that this is a fair rendering of George and Tollefsen’s argument at this point in the book. According to this argument, the issue with ‘quantitative properties’ is not that they represent some degree of a broader property, the way that consciousness might be expressed as a degree of sentience. The problem is rather that no post-conception developments, whether ‘quantitative’ or not, are developments that go to the substantial nature of personhood-possessing creatures. If the animalist criterion of numerical identity is true, only the quality of ‘being human’, established at conception, is part of our substantial nature.

George and Tollefsen define the view they are attacking at this juncture as ‘moral dualism’.24 Moral dualism is the belief that there is a difference between human beings and persons, and hence that not all human beings are necessarily rights-hold- ing persons. Perhaps all human beings begin their lives as non-persons. Understood as the idea that human beings and persons are analytically distinct, even if they overlap, moral dualism is a claim I have accepted from the beginning of this book. I take it that George and Tollefsen do not intend to challenge the analytical distinctness of humanity and moral personhood, because I think they would want to accept that the members of an intelligent alien species could be persons. It is clear, however, that they wish to challenge the view that there could be any instances of living human beings that are not persons. In other words, they may be distinct classifications, but their correspondence is complete.

For clarity, we ought to distinguish moral dualism from the kind of metaphysical dualism we were considering earlier. The dualist thesis I considered before holds that we are numerically identical only with an immaterial mind or essence which can inhabit a human body at one time but not another. The ‘moral dualist’ only claims that humanity and moral personhood are distinct properties, and that one may be a human without being a person. George and Tollefsen’s argument above is effectively meant to establish that moral dualism is incompatible with the animalist conception of numerical identity. The argument and its conclusion can therefore be broken down as follows:

P1. We are owed the moral rights associated with personhood only in virtue of what we are unchangeably, meaning our substantial properties.

P2. We are our human bodies (animalism).

  • 23 ibid.
  • 24 ibid 112.


C1. Our moral rights supervene on our human biology.

P3. We begin to exist as individual human beings at conception.


C2. All human beings from conception are persons (moral dualism is false).

From one angle, this seems to be just another iteration of the substantial identity argument considered above. As was the case there, I believe this argument pushes the conclusions of animalism too far. Even assuming that the animalist view of numerical identity is correct, it seems that personhood essentialism remains a core premise of the argument, and this is a claim the authors have not given us compelling reason to accept. A moral dualist who does not accept personhood essentialism might well agree with the animalist criterion of persisting identity— the view that we are identical with our bodies—but simply hold that ‘we’, human beings, do not possess the quality of personhood at all times in our existence. It is also still open to the moral dualist to deny the impossibility of substantial change and claim that even though personhood is an essential property, it is possible for individuals to change in respect of such properties and still remain the same numerical thing.

It is of course precisely the compatibility of moral dualism and animalism which the authors are contesting. On their view, moral dualism does not fit with the animalist view of numerical identity, since if both were true we would have to abandon the clearly correct proposition that creatures which are persons are worthy of moral respect only in virtue of the kind of things they are. Animalism says that all human beings are numerically and substantially identical with their human bodies, hence come into existence, as the thing that they are, at conception.

Yet the moral dualist might respond that it is not human beings that are persons in virtue of what they unchangeably are, but, rather, personhood-possessing creatures. If those creatures ceased to be persons, they would still be human beings, and still be numerically identical with the thing they have always been. It would remain true, then, that they are in possession of personhood by dint of the kind of thing that they are, even if that nature does not necessarily go hand in hand with the conditions for their persisting numerical identity. To be a person is, surely, to be a very particular (and special) kind of a thing, even if one could cease to be a person and still survive as the same identifiable individual.

Another questionable implication of George and Tollefsen’s argument can be brought out by considering the hypothetical case of zombies. The authors wish to claim both that we are numerically identical to our bodies and that we are persons at all times that we exist as the same living human organism. This seems to give a strange result in the zombie hypothetical. A zombie, we may suppose, is biologically continuous with the human being as she existed before she was zombified. Endorsing the animalist criterion of identity, we would have to say that the human and the zombie it turns into are one and the same thing. And this seems to make sense. When characters in zombie apocalypse dramas suffer the misfortune of being bitten, it strikes us as rational for the other characters to feel pity for the victim who has become something so loathsome, a reaction which would lack intelligibility if the zombie were not identical with the victim. But it seems clearly wrong to say that if the human being pre-zombification was a person, and identical with her human body, then the zombie is also a person. And this is what George and Tollefsen’s argument would apparently commit us to saying in this fantasy scenario.

Lastly, let me return once more to the issue of ‘merely quantitative’ characteristics. For those who believe that certain cognitive abilities or levels of biological development are the conditions for personhood, it will just be true that differences between creatures which are on one metric quantitative can add up to morally significant differences. George and Tollefsen compare a conception of personhood which rests on capacities such as these with the racist attribution of moral worth on the basis of skin colour. ‘The racist’, they say, ‘picks out a shade of skin as a more important characteristic than common humanity in deciding the worth of human beings’.25 However, they continue, ‘between any two human beings, the difference in colour will always be only a difference of degree, a difference that makes no difference to the sorts of beings that each is’. The authors propose that identifying personhood with the onset of developmental capacities which also exist on a spectrum is discriminatory in much the same way. Defenders of developmental thresholds are just like racists who wrongly regard someone as inferior by ‘picking out a characteristic that should be irrelevant to moral respect’^6

This, however, conflates the differences of degree issue—the continuum problem—with their argument about the sorts of morally intrinsic differences that can be relevant for moral status. It is not the fact that shades of skin colourings lack sharp borderlines which leads us to believe skin colour is irrelevant to moral status. It is the fact that we cannot see how skin colour is related to the strong moral considerability that personhood entails. George and Tollefsen seem to make use of the skin colour analogy in the service of arguing that any criterion of personhood which can be located on a wider spectrum (e.g. self-consciousness or rationality on a ‘Sentience Spectrum’) disqualifies that criterion as constitutive of personhood. So the right analogy with skin colour and racism would be to imagine that we did otherwise have sound reason to think that moral status supervenes on a particular skin colour, and then to argue that the fact that colour is a spectrum, or that shadings are never precise, precludes us from identifying personhood with white, black, brown, or yellow skin.

But the fact that all shades of colour exist on a spectrum and blend into one another is not the reason that grounding personhood in skin colour is so obviously erroneous. The reason is that skin colour has no bearing on any of the attributes or capacities which we believe generate moral rights. If, however, we did have sound reason for regarding skin colour as relevant to personhood, the fact that colours sit on a spectrum with no sharp boundaries would be no objection unless

2« ibid 121.

we were convinced that any property which is on some metric quantitative cannot be constitutive of personhood. As we have seen, George and Tollefsen’s main argument for this is that personhood can only supervene on substantial properties, of which, it seems, there is only one: the property of being an individual human organism. This argument I have found unpersuasive. None of this poses any problem with answering the racist of course, because we already know why skin colour has nothing to do with moral status.

  • [1] George and Tollefsen (n 1) 122. 17 ibid. 18 Michael Sandel, The Case Against Perfection: Ethics in the Age of Genetic Engineering (HarvardUniversity Press 2007) 118.
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