1. Equal Consideration

Let us agree that we have reason not to harm nonhuman animals and that our reasons are not merely instrumental. In that sense, animals are not things with which one may do as one likes. It is a further question whether we should end factory farming of the sort opposed by Singer and others. And it is a further question whether we should refrain from killing animals in order to eat them at all.

That we have noninstrumental reason not to harm nonhuman animals is a relatively modest claim. It is not about reasons to prevent the suffering of nonhuman animals, but about reasons not to cause it. The claim is about suffering or harm, not about reasons to confer additional benefits. And it says nothing about the relative strength of reasons not to harm nonhuman animals and reasons that concern our treatment of one another. Singer goes much further, to a principle of equality we can state as follows:

In his words, ‘the interests of every being affected by an action are to be taken into account and given the same weight as like interests of any other being’ (Singer Reference Singer1975: 5). Though it may seem admirably impartial, this claim is problematic.

To begin with a clarification: is it a consequence of this view that, faced with the prospect of saving a human infant or a drowning fox, one might reasonably save the fox? The advocate of equal consideration will insist that it is not because the interests at stake are not alike. The death of the child is a destruction of potential far more harmful than the drowning of the fox; the benefits of which the child is deprived are much greater, as is the corresponding reason. Equal consideration is not subject to such easy refutation.

There is, however, reason to pause over what is assumed by this response. It assumes, along with most advocates of equal consideration, that we can sensibly compare the magnitude of harms and benefits across species or forms of life. We can say, for instance, that the harm to the infant is much greater than the harm to the drowning fox, and that is why the former counts for more than the latter. According to equal consideration, if a harm or benefit to a nonhuman animal is of the same magnitude as a harm or benefit to a human being, this harm or benefit provides a similar reason. The weight of the reason is fixed by the size of the benefit or harm. It is not clear, however, that such comparisons make sense.

In defending equal consideration, Singer admits that ‘comparisons of suffering between members of different species cannot be made precisely’, but contends that ‘precision is not essential’ (Reference Singer1975: 16). This underestimates the difficulty. The problem is not that comparisons of well-being across species are imprecise but that there is no common scale on which to make them. Comparing harms and benefits to a fox and to a human being is less like comparing the genius of artists, where precision is often lacking, and more like comparing the strength of an argument with the strength of a bridge. There is a standard of flourishing for each kind of living thing, determined by how it lives; there is no common standard of flourishing, or conception of benefits and harms, that can be applied to all living things. Being unable to appreciate art, or interact socially, is a serious deprivation for a human being, an impediment to flourishing. It is no impediment for a fox, even if the fox could be trained to do these things. As Elizabeth Anderson writes in a similar context:

The absence of a nonrelative standard of well-being that determines ‘like interests’ can be obscured in several ways. One is the tendency to focus on suffering and more broadly on hedonic benefits and harms, where there may seem to be a common currency: the duration and intensity of pleasures and pains. At least sometimes, it makes sense to say that a nonhuman animal is in more pain than a human child. But unless we are hedonists about well-being, this will not provide the common standard required by equal consideration. First, its scope is limited. It gives us no basis on which to weigh the magnitude of nonhedonic benefits and harms, the child's future relationships against those of the fox, for instance, or their knowledge of the world. (This limitation is especially obvious if we acknowledge benefits and harms to living things that are not animals. Does it make sense to compare the magnitude of the harm involved in an animal's suffering to the harm of a plant's dehydration?) Second, even in the case of hedonic benefits and harms, the magnitude of the benefit or harm is not determined by duration and intensity alone, but by the content of the experience and its relationship to the relevant form of life. The pain of grief at the death of a loved one plays a very different role in our well-being than the pain of a recurrent migraine. The existence of a rough scale of magnitude for the duration and intensity of pleasure and pain does not suffice for a common scale of benefits and harms, even when we restrict ourselves to benefits and harms that essentially involve experience. We cannot make the comparisons required for equal consideration to apply across species or forms of life.

The fact that there is no common scale of well-being, only the flourishing of different kinds of living things, is obscured not just by hedonic myopia but by related comparisons. For instance, we are able to compare proportional well-being across species, as when a given fox is in the 90th percentile of well-being for foxes and a given human is in the 10th percentile. In one sense, the fox is better off. This is not the sense invoked by equal consideration, as we can see when we consider implications for whom to save. Suppose a drowning man would live five more happy years if you saved him from death and a drowning fox would live two years. In proportional terms, the benefit to the fox of being saved is very much greater than the benefit to the human being. It had better not follow that you should save the fox.

We can also compare the weight of practical reasons. Even if we cannot place the interests of a fox and a human child on a common scale of benefit and harm, it makes sense to ask whether we have more reason to care about the social and artistic limitations of a fox than about the social and artistic limitations of a human being. Should we care more about what happens to whales or carp? The answers may be imprecise, but the questions make sense, at least in context. The weight of reasons is a common scale. Again, this is not the scale assumed by equal consideration, which is a scale of well-being, benefit and harm, that is supposed to fix the weight of reasons. If there were such a scale, it would make sense to compare the level of well-being enjoyed by a flourishing whale with the level enjoyed by a flourishing carp. The question here is not which you should rather be, or become, but which is better off, period. That question does not make sense.

If we cannot make cross-species comparisons of well-being, equal consideration may be true, but it will not conflict with humanism because only human beings will have comparable interests. For the rest of this section, I assume, for the sake of argument, that we can make sense of cross-species comparisons of benefit and harm. Serious puzzles remain. They turn on the contrasts between equal consideration and the modest claim that we have noninstrumental reason not to inflict suffering on nonhuman animals.

Both contrasts were signaled above. First, according to equal consideration, we should care not just about the harm we cause to other animals, but about animal suffering as such, and we should care about it as much as we care about the suffering that other animals or accidents of nature cause to us. From this perspective, the suffering of prey animals as they are mauled by predators is ethically akin to the suffering of human infants in an orphanage attacked by wolves. They differ only in the magnitude of harms involved. If equal consideration holds, we have very strong reason to intervene in order to prevent or reduce this suffering if we can. While this idea has been embraced by some, the notion that we should attempt to police the natural world strikes me as bizarre and not just because it would be difficult or cause more harm than it prevents. Like Bernard Williams, ‘I find it hard to avoid the feeling that those answers are pallid and unconvincing rationalizations of a more basic reaction, that there is something altogether crazy about the idea, that it misrepresents our relations to nature’ (Reference Williams2006: 146). Even if we waive this point, the ethical implications of equal consideration for suffering we do not cause seem wrong. Equal consideration implies not just that we have reason to care about the suffering of nonhuman prey but that we have no more reason to care about human suffering as such. Where the harms are of similar magnitude and no other reasons apply, it conflicts with the claim that we should prevent the suffering of human children, not nonhuman animals, if we can prevent only one.

The second contrast is that equal consideration makes us responsible not just for harm to other animals, but for benefits that go beyond the prevention of harm: in general, their interests count as much as ours. This claim interacts with principles of beneficence to generate yet more outlandish results. If we have reason to benefit the less well-off, and we believe, like most proponents of equal consideration, that nonhuman animals are worse off than healthy human beings, we have reason to direct resources to improve their lives, even before those of other humans. That is hard to accept.

In ‘Cognitive Disability, Misfortune, and Justice,’ Jeff McMahan confronts a similar argument that compares nonhuman animals with humans born with severe cognitive disabilities (Reference McMahan1996: 8). He contends that the severely cognitively disabled are not unfortunate in the relevant sense because, while they have low levels of well-being, their native potential for well-being is also low. (I will come back to this claim in section 2.) Likewise, nonhuman animals are not unfortunate in being less well-off than healthy human beings because they lack the potential for more. This mutes the force of the argument for aid if the basis for intervention is not one's level of well-being, as such, but misfortune relative to one's native potential. All the same, McMahan admits that, given equal consideration, animals who fail to realize their potential for well-being make claims on us akin to those of disadvantaged human beings. Rejecting this conclusion, McMahan is led to a bifurcated view on which nonhuman animals and human beings with severe cognitive disabilities fall outside the scope of justice (Reference McMahan1996: 28–31). Equal consideration is false.

What leads Singer and others to equal consideration is not the plausibility of its consequences for animal suffering we do not cause or for actions that benefit nonhuman animals who are less well-off, but the idea that what matters about a benefit or harm is its magnitude, not the kind of creature to which it occurs. To think otherwise, giving more weight to human well-being, is to risk a form of speciesism that gives to sameness of species the role that biological racists give to sameness of race. In section 2, I consider alternatives to speciesism on which our standing is greater than that of other animals. Section 3 asks whether the risk is one we must avoid.

2. Person Species

The sensible thought that we have noninstrumental reason not to harm nonhuman animals does not commit us to equal consideration even if we allow comparisons of well-being across species or forms of life. There is room for a view, or family of views, on which we have a special status for one another: we have reason to minimize each other's suffering, not just the suffering we cause; we have reason to promote and protect each other's interests, especially the interests of those who are less well-off; and we have rights against each other that nonhuman animals do not possess. The nature and content of these rights is a matter of dispute. However, it might be permissible to kill one fox in order to save five foxes where it would be wrong for me to kill you in order to save five other people. You have a right not to be killed even for the sake of saving more lives.

The formulations in the previous paragraph are studiously quiet on the scope of the special status, on who, beyond you and me, it ought to include. For humanists, the scope extends to every human being. We can state this view schematically as follows.

It is humanism that attracts the charge of being speciesist, of giving ethical weight to brute biological difference, to DNA or lineage or the capacity to interbreed, as biological racists give weight to racial differences conceived in brute biological terms.

As a matter of fact, actual racists, even biological racists, do not treat the ethical significance of race as nonderivative. They trace it to the association of race with meaningful capacities: rationality, intelligence, subservience, aggression (Williams Reference Williams2006: 139–40; Kagan Reference Kagan2016: 8). But this is a red herring. It is not as though biological racism would be more defensible if it were less articulate, if racists were to insist that while biological race is unrelated to anything else of value, we have special reason to care about those who share our race, that they have rights against us that others lack. That is an outrageous falsehood. How is humanism different?

Moved by this rhetorical question, most critics of equal consideration try to derive the special significance we have for one another from a related property, not shared by other animals, that correlates with being human. But the correlation is often imperfect: some human beings are excluded. In this section, I criticize alternatives to humanism that exclude some human beings, formulate a view on which all human beings count, argue that it is more defensible than is often supposed, and explain why I think it is false.

It has become standard in philosophy to use the term ‘person’ in a way that does not apply to every human being. Shelly Kagan is representative in defining a person as ‘a being that is rational and self-conscious, aware of itself as one being among others, extended through time’ (Reference Kagan2016: 9). Imagining Superman, a nonhuman person who was born on Krypton, Kagan suggests that most of us are not really speciesists, holding that Superman's interests count for less than ours, but ‘personists’ who think that persons have special significance. Adapting the schematic formula above, we can state the basic idea.

It is worth noting a gap in Kagan's reasoning. It does not follow from humanism that Superman counts for less than us, at most it follows that if he counts as much or in the same way, he does so for a different reason. That does not strike me as implausible. It is not at all obvious to me that the reason I have to care about Superman is the same reason I have to care about human beings as such. I might have reason to care in a special way about fellow human beings and a reason to care about persons like him.

Still, personism has definite appeal. Critics who object to humanism as speciesist typically concede that, unlike being human, being a person is an ethically relevant property. The problem is rather that the view is too restrictive. Human infants are not persons in the philosophers’ sense nor are those at the end of life who have lost their capacity for reason, self-conscious thought, or awareness of others. Yet, they have distinctive rights nonhuman animals lack: they share our special status even if what it calls for in their case is different from what it calls for in relation to us—hence, attempts to expand the scope of personism to include those who have lost personhood or have yet to acquire it. If we define a potential person as someone who has or had the potential to become a person, we can formulate the corresponding view.

Potential personism needs a suitable theory of potential. To say that a human infant has the potential to become a person is not to say that she can do so without assistance from others. What sorts of external intervention count as helping something to realize its own potential? What sorts confer a potential it did not already have? (McMahan [Reference McMahan1996: 21–29] has anxieties on these lines, though he continues to employ the concept of potential.)

Some will object to potential personism because it suggests that an early embryo, with its potential to become a person, has the same rights we do and that this has questionable implications for the ethics of abortion. (The same could be said of humanism and species personism, to be discussed below.) I think this is a mistake. To say that early embryos have equal rights is not to settle the content of those rights. Do we have a right not to be killed or a right not to be killed when we have reached a certain level of sentience or biological development? To accept the equal and distinctive worth of all human beings, including the unborn, is to leave this question unresolved.

The more basic problem is that the view is too restrictive. As McMahan notes, humans born with severe congenital cognitive disabilities are not potential persons (Reference McMahan2008: 88). If the basis of their cognitive limitations is genetic, present from conception, they never had the potential to become persons. According to potential personism, they lack the special significance shared by you and me. They may have derivative significance because of their relationship with other people, in particular, their parents. But in themselves, they are equivalent to other animals.

This consequence is unacceptable. Even if the reasons that derive from relationships are weighty, treating them as the only reasons to care about children born with severe congenital cognitive disabilities more than we care about other animals is to deny them the distinctive status of human beings. I worry that philosophers have forgotten how disturbing this view is. Its advocates will insist that the ethical equivalence of nonhuman animals and those with severe congenital cognitive disabilities can be combined with a revisionary account of our treatment of other animals on which their interests matter more than we had previously supposed. But unless we move to equal consideration, with its implausible implications, our view will give too little weight to suffering we do not cause and to the positive interests of those with severe congenital cognitive disabilities. According to potential personism, if human beings with such conditions are killed by wolves, then, apart from their relation to other people, that is no more important than the suffering and death of other prey. Likewise if they die by natural causes, however painful. We might have thought that their unfortunate condition demands compassion, that we should strive to make their lives as fulfilling or at least as comfortable as we can. For potential personists, we have, in general, no more reason to do this than we have to benefit nonhuman animals whose flourishing is impaired. What reasons we do have derive from their relationships with other people, not the claims they make on us themselves.

If you do not recoil from these conclusions, the argument ends here. If you do, the question is how to avoid them. How to extend the scope of our special status to encompass those with severe congenital cognitive disabilities without falling into an illicit speciesism? In a recent discussion, Kagan offers a distinctive variant of potential personism that appeals not to potential but to metaphysical possibility. If a potential person is one who has or had the potential to become a person, a modal person is one who could have been a person. Hence the following position.

To the extent that those with severe congenital cognitive disabilities could have developed differently, modal personism finds them ethically equivalent to you and me. But the improvement is limited, in that it is hostage to the metaphysics of identity. As Kagan concedes, if our genetic endowment is essential to us and a human is born with a genetic program for severe cognitive disability, modal personism denies her special status (Reference Kagan2016: 16–18). Kagan accepts this implication, but in my view, it is comparable to the implications of potential personism. The fact that the implication concerns a smaller group of individuals and that it turns on difficult questions of metaphysics does not make things better: these questions are irrelevant to the ethical status of humans born with severe cognitive disabilities. At the same time, modal personism threatens to be too inclusive. If it is metaphysically possible to ‘personize’ nonhuman animals, intervening in their genes so that they develop into persons without loss of identity, these animals are modal persons. If modal personism is true, then, even when this possibility is unrealized, we have reason to care about these animals that we do not have to care about other animals, and they have rights against us that other animals lack (McMahan Reference McMahan2016: 29). Again, this seems wrong. It does not make a difference to the ethical status of nonhuman animals whether it is possible to intervene in their development in this way.

On the way to proposing modal personism, Kagan mentions what I think is the most plausible alternative to humanism. He defines a person species as a species whose normal adult members are persons (Reference Kagan2016: 12). Using this concept we can state a final personist claim.

‘Species personism’ is a new name for a traditional view. Although Stanley Benn is sometimes misread as a humanist, this was his view in a classic essay: ‘we respect the interests of men and give them priority over dogs not insofar as they are rational, but because rationality is the human norm’ (Reference Benn, Pennock and Chapman1967: 71; for the misreading of Benn, see Waldron Reference Waldron2017: 229–30). Species personism gives no special weight to being human or to those who share our species. It dignifies the members of any person species, including Superman and the rational Martians of philosophical science fiction. Still, like humanism, and unlike every other view considered so far, species personism gives special status to all human beings, including those with severe congenital cognitive disabilities and ones who are not potential or modal persons.

If species personism is not speciesist, giving weight to brute biological difference, why do critics of humanism reject it? Some are moved by attachment to a ‘moral individualism’ on which the ethical status of an individual supervenes on its intrinsic properties (see, for instance, McMahan Reference McMahan2005: 353–55). The property of belonging to a species whose normal adult members are persons is not intrinsic. But this objection is question-begging. Why accept moral individualism in the first place? Defenders of species personism will regard their view as a refutation of it. They may add that it is not an implication of their view that a personized chimpanzee does not warrant special concern or have distinctive rights, only that it does so on different grounds. Like humanism, species personism describes a sufficient reason, not a necessary one; it is not inconsistent with personism.

Instead of assuming individualism, it is more fruitful to focus on a challenge from Kagan. He points out that any individual is a member of many groups, social, biological, and otherwise. The question thus arises, ‘what's so special about one's species? Why is this group the one particular group that we should focus on, when looking for morally relevant properties possessed by typical members of the group?’ (Reference Kagan2016: 14)

It makes sense to ask why merely being a member of a species whose normal adult members are persons is enough to give one special status. But there is a plausible answer that goes back to an issue raised and set aside in section 1. In discussing Singer's view, I questioned the intelligibility of cross-species comparisons of well-being, urging instead that standards of flourishing are relative to kinds of living things. What counts as benefit and harm, flourishing and failure for an individual creature depends on its species, on what kind of creature it is. That is why species is an ethically relevant category in a way that genus, family membership, race, and sex are not. The first thing to say about human beings born with severe cognitive disabilities is that their condition is a tragedy, as similar cognitive potential would not be in a creature of a different kind. (This is consistent with the view that some disabilities are not essentially harmful and that the harms they generate turn on imperfect social conditions [Barnes Reference Barnes2016]; I doubt that this applies to the disabilities at issue here.) As Rawls remarked in A Theory of Justice: ‘When someone lacks the requisite potentiality [e.g., for personhood] either from birth or accident, this is regarded as a defect or deprivation’ (Reference Rawls1970: 506). That the proper response to this misfortune is pity or grief reflects the fact that we have reason to care about those with severe cognitive disabilities that we do not have to care about other animals with similar capacities and that they make claims on us that those animals do not.

In a challenging treatment of related questions, McMahan agrees that it is not a misfortune for a nonhuman animal that it cannot become a person. But he argues that the same is true of a human being born with severe congenital cognitive disabilities. If McMahan is right, this undermines the proposed defense of species personism. McMahan argues for his surprising claim about the cognitively disabled by criticizing what he calls the ‘Species Norm Account’. On this account, ‘an animal is not unfortunate for having a low level of well-being if that level is characteristic or appropriate for beings of its kind … how well off a being is depends on how its level of well-being compares to the levels accessible to those with cognitive and emotional capacities that are the norm for the species of which it is a member’ (Reference McMahan1996: 10). McMahan makes two main objections. First, contrary to the species norm account, it is not a misfortune for an infant to be born without cerebral hemispheres because ‘it is not the sort of being that can be badly off’: ‘It makes no more sense to say that an anencephalic [infant] is unfortunate or badly off, than it does to say these things of a plant’ (Reference McMahan1996: 13). Second, if a chimpanzee were genetically engineered to have the cognitive and emotional capacities of a ten-year-old human being and it were to lose these capacities, that would be a grave misfortune even if it were to live the rest of its life at a level of well-being that is the norm for its species (Reference McMahan1996: 13). The species norm account conflicts with this assessment. In its place, McMahan proposes a native potential account, on which fortune is measured by how one's well-being compares to highest levels one has the potential to achieve (Reference McMahan1996: 18–24). On this account, human beings with severe congenital cognitive disabilities are not unfortunate or badly off since they never had the potential for significantly higher levels of well-being.

There is a lot to say about McMahan's intervention. First, it is not a datum that those born anencephalic are not unfortunate or badly off. In fact, I am sure that it is false. In any case, it is not a suitable premise in this debate but a conclusion in need of argument. Second, the species norm account is definitely wrong. We do not need to imagine genetically engineered chimps to see that there is misfortune in being reduced from a condition of exceptional flourishing to a level of flourishing that is the species norm. Third, the claim that human flourishing is relative to species or form of life is consistent with the claim that McMahan's chimp is harmed. If nothing else, the desires it forms in its modified condition go largely unsatisfied, and the satisfaction of innocent desire is of benefit to chimpanzees. At the same time, I hesitate to say that the genetic engineering that gave the chimpanzee its ‘enhanced’ capacities was beneficial because it threatens to exclude the chimp from its characteristic species life. Finally, despite a superficial similarity, the species norm account is not only different from but inconsistent with my position that welfare cannot be understood except in relation to species or form of life. McMahan assumes the opposite. He appeals to nonrelative levels of well-being, first for an individual, then for typical members of a species, and he compares the two. If there were a common scale of this kind, it would make sense to ask whether a flourishing whale is at a higher level of well-being than a flourishing carp or to assert, with McMahan (Reference McMahan1996: 9–10), that we enjoy more well-being than nonhuman animals. But it does not make sense.

The upshot is that while we should reject the species norm account, there is no reason to doubt that human beings born anencephalic or with severe congenital cognitive disabilities are unfortunate in being badly off. McMahan's argument does not speak to the view that standards of flourishing are kind-relative. He gives no reason to doubt that species or form of life is ethically relevant in a way that distinguishes species personism from ethical principles that appeal to membership in groups of other kinds.

Despite this, I do not accept species personism. One way to approach my doubts is through a familiar concern about personism, namely, that the capacities constitutive of personhood form a spectrum (recent discussions include McMahan Reference McMahan2008: 93–104 and Waldron Reference Waldron2017: 113–23). On Kagan's definition, a person is rational, self-conscious, and aware of itself as one being among others extended through time. A standard objection to personism is that the definition of ‘person’ cites a cluster of semi-independent properties, each of which comes by degree. Individuals differ in their levels of rationality, self-consciousness, consciousness of others, and conceptions of time. It is tempting to make additions to Kagan's list: why not focus on the capacity for love, respect, or reciprocal recognition? The more gradual and various the capacities involved in personhood, the more questionable it is why and how a particular threshold or region in this space should mark a difference in ethical kind.

A similar question can be put to species personists. If the capacities that constitute personhood form a spectrum, why should species whose normal adult members have those capacities to a given degree or in a given formation be ethically distinguished from others? Why should they have rights against us that others lack and interests that count for more? The problem is not that ‘person’ is vague but that ethical discontinuity has been imposed on, and must somehow be justified by, capacities whose variation is scalar and multivalent.

Faced with this apparent discrepancy, the species personist can go either of two ways. One is to conclude that ethical status comes by degree, proportioned to the capacities characteristic of a species. The other is to find a meaningful discontinuity among the relevant capacities that could ground a special status. Working through the defects of the first response will help us see why there is a problem with the second.

On the gradualist approach, degrees or variations in ethical status turn on degrees or variations in the rational capacities characteristic of a species: the capacity to act for reasons, to be self-conscious, to be aware of others, to comprehend one's persistence in time, capacities for love, respect, and mutual recognition. Members of species whose rational capacities are inferior to ours count proportionately less and have fewer rights than we do against one another. The scales at work here are suspiciously anthropocentric, organized by similarity to us. But they also raise the opposite concern. If there are species whose rational capacities exceed those characteristic of humanity, gradualism would imply that we have more reason to care about them than we do about one another, and they might have rights against us that we do not possess.

The basic objection to gradualism is that it conflates one form of merit, the excellence of rational capacities, with ethical worth. Our ethical equality with one another does not rest on equality of merit in any form, nor does it rest on the more indirect relation to equal merit of belonging to a species whose normal adult members have rational capacities of the same description and degree. At the root of gradualism is a conflation of the two kinds of respect distinguished by Stephen Darwall (Reference Darwall1977): appraisal respect and recognition respect. Appraisal respect is a response to admirable qualities, a response merited to different degrees and in different ways by different individuals. Recognition respect is the respect we should have for every human being, regardless of his or her particular merits. In effect, gradualism treats recognition respect as if it were an appraisal of the kind of creature one is. One's ethical significance depends on the form and degree of appraisal respect appropriate to one's kind.

Understood in this way, recognition respect is fundamentally incoherent. It is a mistake to appraise an individual not on the basis of its own qualities but on the basis of its species norm. We should be individualists about appraisal respect. But to adopt an individualist form of gradualism, on which degrees or variations in ethical status turns on degrees or variations in an individual's rational capacities, so that some of us are more important than others, is to give up on the idea of recognition respect. A failure to grasp the distinction between appraisal and recognition respect is hidden by the indirectness of species personism in its gradualist form, but it remains at work. The idea of recognition respect is antithetical to the hierarchy of merit invoked by gradualism, a hierarchy that echoes anachronistic images of the Great Chain of Being and survives in McMahan's belief that our level of well-being is greater than that of nonhuman animals.

Species personists should not be ethical gradualists. They must point to a discontinuity in the spectrum of rational capacities, definitive of personhood, that gives us and others like us special status. There are views that take this shape. Suppose that, while nonhuman animals engage in purposive action, they lack the capacity to act for reasons. To act for reasons is to act on what one takes to be a reason for acting; it calls on capacities for self-knowledge and self-reflection. Then assume a form of Kantian constitutivism on which one cannot have these capacities without being such as to respect the rights and interests of others. A sensitivity to other people and to members of person species is contained in the capacity to act for reasons; justice and benevolence are entailed by the perfect exercise of this capacity. In failing to respect the rights and interest of others, one falls short of standards internal to its proper functioning. (The most influential development of this idea in recent years is due to Korsgaard Reference Korsgaard1996, Reference Korsgaard2009.) On these assumptions, it would make sense to associate a distinctive ethical status with the capacity to act for reasons and thus with being a member of a species of which that capacity is characteristic. The capacity to act for reasons contains the capacity to live on decent terms with those who share it.

As I have argued elsewhere, however, constitutivism about practical reason is false: although it involves self-knowledge, the capacity to act for reasons is too minimal a ground for the derivation of rational norms, let alone a sensitivity to the rights and interests of others. (See Reasons without Rationalism [Setiya Reference Setiya2007] and for revisions and extensions, Setiya Reference Setiya and Tenenbaum2010 and Setiya Reference Setiya, Vargas and Yaffe2014b). I will not repeat these arguments here, but I will note that Kantian constitutivism is widely thought of as implausibly ambitious. This matters because its truth, or the truth of something like it, is not just sufficient but necessary for species personism in its nongradualist form. If the capacity to act for reasons is a mere capacity for cognitive control of what one is doing and not a foundation for ethics—if it is consistent with complete indifference to the rights and interests and even the existence of others—it has no more claim on our ethical attention than any other form of intelligence. It is a suitable basis for positive appraisal, perhaps, but not for recognition respect. That the property in question is not scalar does not save the species personist from a basic conflation of the two.

We can generalize the point. The question for the species personist is why being a member of a person species grounds a distinctive ethical status. Why is it a basis for recognition respect, not just a reason for admiration or positive appraisal? The only adequate response is that belonging to a person species makes one part of the ethical community. It can do so only if sensitivity to the rights and interests of others is characteristic of such species: it is only through imperfect development or misfortune that members of person species lack this sensitivity. Since the defining feature of a person species is that its mature, adult members are persons, this can be true, in turn, only if being a person entails being sensitive to the rights and interests of others, as in Kantian constitutivism. The species personist need not identify personhood with the capacity to act for reasons or derive the standards of practical reason from this capacity, but she must adopt a structurally similar view, subject to similar objections, on which the standards of practical reason derive from the nature of personhood as such. The answer to the question why belonging to a person species grounds recognition respect is that the capacity for ethical recognition is characteristic of such species. The species personist needs Kantian constitutivism or something comparably ambitious in order to account for the ethical significance of personhood and thus of person species.

This argument shows the entanglement of a substantive ethical question, about the special status of human beings, with the foundations of practical reason. There is a path from species personism to a form of constitutivism on which the standards of practical reason derive from the nature of personhood—as, perhaps, from the capacity to act for reasons—and from the failure of the latter to the failure of the former. There is no separation here between normative ethics and metaethics. An adequate defense of humanism will reflect this interaction, too.

3. Humanism

The argument so far is that bifurcated views of ethical status are beset by problems. Humanism is charged with giving illicit significance to brute biological difference in a way that is akin to biological racism. In its individualist forms, personism excludes those with severe congenital cognitive disabilities. Species personism does better on this count, but without appeal to a dubious and disputed view in the foundations of ethics, it fails to identify a proper ground for recognition rather than appraisal respect. Unless it has ethical implications, belonging to a species whose normal adult members have particular rational capacities is not a source of distinctive rights or a basis for special concern.

If we reject bifurcated views, we will be pushed back to equal consideration with its attendant difficulties. Proponents of equal consideration motivate their view in part by pointing to the defects of others. They are especially apt to object to humanism as speciesist. Having criticized alternatives, it is to time to examine this objection in more depth.

Like the other principles we have considered, humanism is framed in the first person plural. These principles make claims about the reasons we have, where we are human beings capable of responding to reasons. They do not say whether these reasons apply to other rational beings, should they exist. In some cases, proponents of a principle may be tempted by that stronger claim. Personists may believe that every rational being has reason to care about other rational beings that they do not have to care about nonrational animals. But humanism is not plausibly interpreted that way. The idea is not that every rational being has reason to care about humans as such so that human beings have a kind of absolute value. It is that rational human beings, in particular, have reason to care about other human beings. The distinctive worth of humans as such is a value they have for us.

In saying this, I agree with Williams's view in ‘The Human Prejudice’ (Reference Williams2006: 137–38) though I think his presentation is potentially misleading. Williams seems to conflate a normative question about the scope of certain reasons with a metaphysical question about the very idea of absolute worth. We need not doubt the cogency of this idea or the concept of a reason that applies to every rational being in order to make the normative point that humanist reasons are not of this kind. Williams describes such reasons in terms of a ‘loyalty to, or identity with, one's species’ akin to that of ‘a human group defending its cultural, possibly ethnic, identity’ (Reference Williams2006: 150, 149). Humanist reasons are akin to reasons of loyalty in being relational: reasons we have, as human beings, to care about other human beings. But the analogy is imperfect. Humanism is quite different from loyalty of other forms. Loyalty to a cultural or ethnic group could not justify the attribution of distinctive rights or the kind of concern that humanists defend.

More helpful is Williams's blunt insistence that unlike appeal to race or sex as a basis for special treatment, appeal to another's humanity does not stand in need of further reasons (Reference Williams2006: 139–40). The latter claim is disdained by critics as speciesist for giving weight to brute biological difference. The claim improves on biological racism only in being less articulate. But while it is true that a refusal to give reasons would not save the biological racist, that is not because humanity and biological race belong to a common pool of biological concepts whose ethical significance cannot be nonderivative, but because that is true specifically of race.

It is vital here to distinguish the concept human being from conceptions of biological species defined by genetics, evolutionary lineage, or, in the case of sexually reproducing organisms, the capacity to interbreed. This distinction has been obscured in part because it is associated with more contentious claims (as, for instance, in McMahan Reference McMahan2005: 371–72, 379). Thus Cora Diamond suggests that human being is not a ‘biological notion’ and that to grasp this concept fully is, in part, ‘to know what it is to look at another human being with … recognition or with its denial’ (Reference Diamond1988: 265). In distinguishing the concept human being from concepts of scientific biology, one need not deny that it is in some sense a biological concept, a concept of ‘folk biology’ that picks out a kind of living thing. One need not insist that ‘life with this concept’ entails an ethical sensitivity, as Diamond does. The point is simply that the concept human being is one we had before we had any conception of genetics or evolution or a scientific theory of speciation.Footnote ¹

This situation is commonplace. We had the concept water before we had any inkling of its chemistry, the concept heat before we knew about molecular kinetic energy. The concept heat is not the concept mean molecular kinetic energy even if heat is mean molecular kinetic energy. The same applies to the concept human being and concepts involved in the scientific biology of species. This modest point is enough to disrupt the allegation of speciesism. To take a recent example, McMahan writes: ‘Mere co-membership in the human species is … like co-membership in a racial group in being a purely biological relation: a matter of genealogy, genetics, or capacity for interbreeding, depending on one's favored understanding of the concept of a species. It is hard to see how this could be intrinsically significant’ (McMahan Reference McMahan2005: 361; see also Waldron [Reference Waldron2017: 87–88] on appeal to human DNA, which he associates with humanism). Set aside whether membership in a racial group really is a purely biological relation. We can agree with McMahan that facts about genealogy, genetics, and interbreeding are not reasons for special concern or respect for rights. We could even agree that for N to be a fellow human being is for some relation of genealogy, genetics, or interbreeding to hold between us.Footnote ² It would not follow that the fact that N is a fellow human being is not a reason for special concern or respect for rights.

Reasons are facts in that they are true propositions: they are the sort of things that can be known or believed and by which it is rational to be moved. (This follows from a conception of reasons as premises of sound reasoning, as in Setiya Reference Setiya2014a, but it is consistent with other views.) It is not in general true that when the fact that p is a reason to ϕ, and for it to be the case that p is for it to be the case that q, the fact that q is a reason to ϕ. The proposition that p need not be the same as the proposition that q. Suppose it is true that pain is C-fibres firing. Other things being equal, the fact that someone is in pain is a reason to help them. By hypothesis, for them to be in pain is for their C-fibers to be firing. But if I am ignorant of this identity, facts about C-fibers will not provide me with reasons to care. I might be rationally indifferent to the discovery that your C-fibers are firing, as I could not be rationally indifferent to the fact that you are in pain. (We must not be misled here by the presence of related reasons. The conjunctive fact that your C-fibers are firing and that pain is C-fibers firing is a reason to help you even though its first conjunct is not.)

What happens if I learn that pain is C-fibers firing? Should I cease to care about pain on the ground that the state of someone's C-fibers has no significance of its own? Not at all. I should not lose my aversion to pain on the ground that I have no prior reason to care what your C-fibers do. Instead, I should gain a derivative interest in C-fibers. In just the same way, the humanist does not give ‘intrinsic’ or nonderivative significance to genealogy, genetics, or the capacity to interbreed, but to humanity. At most we can say that humanists give derivative significance to biological science insofar as it bears on being human. But then they are not subject to McMahan's complaint.

Of course, McMahan and others may flatly insist that the concept human being, while distinct from the concepts of scientific biology, is equally insignificant, that the truths in which it figures—for instance, that a baby born anencephalic is still a human being—are not reasons for respect or concern. But it is hard to see an argument behind this insistence except by mistaken inference from the ethical insignificance of genealogy, genetics, and interbreeding.

This is not to deny the force of the question why being human counts as an ethically relevant property in a way that race and sex do not, a question that persists even when we extricate the concept being human from scientific theories of species. This is the question asked, in section 2, about being a person or a member of a person species. There I argued from species personism to Kantian constitutivism. Unless it plays a role in the foundations of ethics—explaining the standards of practical reason or our knowledge of them—being a person or a member of a person species is worthy of appraisal not recognition respect. It involves an admirable form of intelligence, perhaps, but is not the ground of our ethical recognition of one another.

Parallel reasoning applies to humanism, though the foundational commitments of the humanist are, I believe, more plausible than those of the species personist. In order to affirm that being human is ethically significant, an appropriate ground of recognition respect, humanists must follow the tradition that descends from Aristotle, which gives a constitutive role in ethics to the facts of human life. That a human response is rational or justified is not independent of the fact that this response or affirmation of this response is functional for us, where the standards of functioning derive from the natural history of human beings in a way that is akin to standards of human flourishing, as conceived above.

The details are contentious. We need an account of proper functioning for the parts and operations of living things that can extend to human life, and we need to locate the standards of practical reason within it. On the simplest view, the trait of practical rationality is the perfect functioning of human psychology with respect to practical thought (see Foot Reference Foot2001; Thompson Reference Thompson, Hindrichs and Honneth2013). On a view I find more plausible, we begin with ethical judgment as a capacity that regulates human life. Practical rationality is what such judgment tracks when it functions well. (For a defense of this approach, under the heading of ‘Natural Externalism’, see Setiya Reference Setiya2012: ch. 4.) Either way, being human is not of mere natural-historical interest. For Kantian constitutivists, the capacity to act for reasons contains the capacity to live on decent terms with those who share it. That would explain why this capacity, or membership in a species of which it is characteristic, grounds a distinctive ethical status. Likewise, for Aristotelians, the standards of ethics are internal to the natural history of human life. It belongs to their proper functioning that human beings conform to or recognize these standards. That is why the fact that N is a fellow human being is a ground of recognition respect.

As before, the substantive question of our distinctive ethical status, our reason to respect and care about other human beings, is entangled with the nature of practical reason. Humanism needs Aristotelian foundations. This is not the place to develop a specific version of Aristotelian ethics though I have begun to do so elsewhere.Footnote ³ My contentions are more modest: that there is an approach to practical reason and ethical knowledge, inspired by Aristotle, that is congenial to humanism and that humanism cannot survive without it.Footnote ⁴

The Aristotelian premise of humanism helps to show why it is different from sexism or biological racism. For there is no credible theory of ethics on which its foundations appeal to race or sex nor is there reason to believe that human beings are by nature racist or sexist in ways that might support an Aristotelian defense of such repugnant views (Setiya Reference Setiya2012: 142–58). The entanglement of normative ethics and metaethics thus points back to the question of speciesism. Why is being human ethically relevant where biological race is not? In part, because the concept being human, while broadly biological, is distinct from conceptions of species in scientific biology whose significance is derivative at best. In part, because it plays a role in the metaphysics and epistemology of ethics that could be played by race only if Aristotle were right about the existence of natural slaves.Footnote ⁵