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Viewed from a distance, the natural world often presents a vista of sublime, majestic placidity. Yet beneath the foliage and hidden from the distant eye, a vast, unceasing slaughter rages. Wherever there is animal life, predators are stalking, chasing, capturing, killing, and devouring their prey. Agonized suffering and violent death are ubiquitous and continuous. This hidden carnage provided one ground for the philosophical pessimism of Schopenhauer, who contended that “one simple test of the claim that the pleasure in the world outweighs the pain…is to compare the feelings of an animal that is devouring another with those of the animal being devoured.”

Theologians’ labors will not be over even if they are finally able to justify the ways of God to man. For God must answer to animals as well.

The continuous, incalculable suffering of animals is also an important though largely neglected element in the traditional theological “problem of evil” ─ the problem of reconciling the existence of evil with the existence of a benevolent, omnipotent god. The suffering of animals is particularly challenging because it is not amenable to the familiar palliative explanations of human suffering. Animals are assumed not to have free will and thus to be unable either to choose evil or deserve to suffer it. Neither are they assumed to have immortal souls; hence there can be no expectation that they will be compensated for their suffering in a celestial afterlife. Nor do they appear to be conspicuously elevated or ennobled by the final suffering they endure in a predator’s jaws. Theologians have had enough trouble explaining to their human flocks why a loving god permits them to suffer; but their labors will not be over even if they are finally able to justify the ways of God to man. For God must answer to animals as well.

Erin Schell

If I had been in a position to design and create a world, I would have tried to arrange for all conscious individuals to be able to survive without tormenting and killing other conscious individuals. I hope most other people would have done the same. Certainly this and related ideas have been entertained since human beings began to reflect on the fearful nature of their world — for example, when the prophet Isaiah, writing in the 8th century B.C.E., sketched a few of the elements of his utopian vision. He began with people’s abandonment of war: “They shall beat their swords into plowshares, and their spears into pruning hooks: nation shall not lift up sword against nation.” But human beings would not be the only ones to change; animals would join us in universal veganism: “The wolf also shall dwell with the lamb, and the leopard shall lie down with the kid; and the calf and the young lion and the fatling together; and the little child shall lead them. And the cow and the bear shall feed; their young ones shall lie down together; and the lion shall eat straw like the ox.” (Isaiah 2: 4 and 11: 6-7)

Isaiah was, of course, looking to the future rather than indulging in whimsical fantasies of doing a better job of Creation, and we should do the same. We should start by withdrawing our own participation in the mass orgy of preying and feeding upon the weak.

Our own form of predation is of course more refined than those of other meat-eaters, who must capture their prey and tear it apart as it struggles to escape. We instead employ professionals to breed our prey in captivity and prepare their bodies for us behind a veil of propriety, so that our sensibilities are spared the recognition that we too are predators, red in tooth if not in claw (though some of us, for reasons I have never understood, do go to the trouble to paint their vestigial claws a sanguinary hue). The reality behind the veil is, however, far worse than that in the natural world. Our factory farms, which supply most of the meat and eggs consumed in developed societies, inflict a lifetime of misery and torment on our prey, in contrast to the relatively brief agonies endured by the victims of predators in the wild. From the moral perspective, there is nothing that can plausibly be said in defense of this practice. To be entitled to regard ourselves as civilized, we must, like Isaiah’s morally reformed lion, eat straw like the ox, or at least the moral equivalent of straw.

If we could arrange the gradual extinction of carnivorous species, replacing them with new herbivorous ones, ought we to do it?

But ought we to go further? Suppose that we could arrange the gradual extinction of carnivorous species, replacing them with new herbivorous ones. Or suppose that we could intervene genetically, so that currently carnivorous species would gradually evolve into herbivorous ones, thereby fulfilling Isaiah’s prophecy. If we could bring about the end of predation by one or the other of these means at little cost to ourselves, ought we to do it?

I concede, of course, that it would be unwise to attempt any such change given the current state of our scientific understanding. Our ignorance of the potential ramifications of our interventions in the natural world remains profound. Efforts to eliminate certain species and create new ones would have many unforeseeable and potentially catastrophic effects.

Perhaps one of the more benign scenarios is that action to reduce predation would create a Malthusian dystopia in the animal world, with higher birth rates among herbivores, overcrowding, and insufficient resources to sustain the larger populations. Instead of being killed quickly by predators, the members of species that once were prey would die slowly, painfully, and in greater numbers from starvation and disease.

Yet our relentless efforts to increase individual wealth and power are already causing massive, precipitate changes in the natural world. Many thousands of animal species either have been or are being driven to extinction as a side effect of our activities. Knowing this, we have thus far been largely unwilling even to moderate our rapacity to mitigate these effects. If, however, we were to become more amenable to exercising restraint, it is conceivable that we could do so in a selective manner, favoring the survival of some species over others. The question might then arise whether to modify our activities in ways that would favor the survival of herbivorous rather than carnivorous species.

At a minimum, we ought to be clear in advance about the values that should guide such choices if they ever arise, or if our scientific knowledge ever advances to a point at which we could seek to eliminate, alter, or replace certain species with a high degree of confidence in our predictions about the short- and long-term effects of our action. Rather than continuing to collide with the natural world with reckless indifference, we should prepare ourselves now to be able to act wisely and deliberately when the range of our choices eventually expands.

There is no reason to suppose that a species has special sanctity simply because it arose in the natural process of evolution.

The suggestion that we consider whether and how we might exercise control over the prospects of different animal species, perhaps eventually selecting some for extinction and others for survival in accordance with our moral values, will undoubtedly strike most people as an instance of potentially tragic hubris, presumptuousness on a cosmic scale. The accusation most likely to be heard is that we would be “playing God,” impiously usurping prerogatives that belong to the deity alone. This has been a familiar refrain in the many instances in which devotees of one religion or another have sought to obstruct attempts to mitigate human suffering by, for example, introducing new medicines or medical practices, permitting and even facilitating suicide, legalizing a constrained practice of euthanasia, and so on. So it would be surprising if this same claim were not brought into service in opposition to the reduction of suffering among animals as well. Yet there are at least two good replies to it.

One is that it singles out deliberate, morally-motivated action for special condemnation, while implicitly sanctioning morally neutral action that foreseeably has the same effects as long as those effects are not intended. One plays God, for example, if one administers a lethal injection to a patient at her own request in order to end her agony, but not if one gives her a largely ineffective analgesic only to mitigate the agony, though knowing that it will kill her as a side effect. But it is hard to believe that any self-respecting deity would be impressed by the distinction. If the first act encroaches on divine prerogatives, the second does as well.

The second response to the accusation of playing God is simple and decisive. It is that there is no deity whose prerogatives we might usurp. To the extent that these matters are up to anyone, they are up to us alone. Since it is too late to prevent human action from affecting the prospects for survival of many animal species, we ought to guide and control the effects of our action to the greatest extent we can in order to bring about the morally best, or least bad, outcomes that remain possible.

Another equally unpersuasive objection to the suggestion that we ought to eliminate carnivorism if we could do so without major ecological disruption is that this would be “against Nature.” This slogan also has a long history of deployment in crusades to ensure that human cultures remain primitive. And like the appeal to the sovereignty of a deity, it too presupposes an indefensible metaphysics. Nature is not a purposive agent, much less a wise one. There is no reason to suppose that a species has special sanctity simply because it arose in the natural process of evolution.

Many people believe that what happens among animals in the wild is not our responsibility, and indeed that what they do among themselves is none of our business. They have their own forms of life, quite different from our own, and we have no right to intrude upon them or to impose our anthropocentric values on them.

Even if we are not morally required to prevent suffering among animals in the wild for which we are not responsible, we do have a moral reason to prevent it.

There is an element of truth in this view, which is that our moral reason to prevent harm for which we would not be responsible is weaker than our reason not to cause harm. Our primary duty with respect to animals is therefore to stop tormenting and killing them as a means of satisfying our desire to taste certain flavors or to decorate our bodies in certain ways. But if suffering is bad for animals when we cause it, it is also bad for them when other animals cause it. That suffering is bad for those who experience it is not a human prejudice; nor is an effort to prevent wild animals from suffering a moralistic attempt to police the behavior of other animals. Even if we are not morally required to prevent suffering among animals in the wild for which we are not responsible, we do have a moral reason to prevent it, just as we have a general moral reason to prevent suffering among human beings that is independent both of the cause of the suffering and of our relation to the victims. The main constraint on the permissibility of acting on our reason to prevent suffering is that our action should not cause bad effects that would be worse than those we could prevent.

That is the central issue raised by whether we ought to try to eliminate carnivorism. Because the elimination of carnivorism would require the extinction of carnivorous species, or at least their radical genetic alteration, which might be equivalent or tantamount to extinction, it might well be that the losses in value would outweigh any putative gains. Not only are most or all animal species of some instrumental value, but it is also arguable that all species have intrinsic value. As Ronald Dworkin has observed, “we tend to treat distinct animal species (though not individual animals) as sacred. We think it very important, and worth a considerable economic expense, to protect endangered species from destruction.” When Dworkin says that animal species are sacred, he means that their existence is good in a way that need not be good for anyone; nor is it good in the sense that it would be better if there were more species, so that we would have reason to create new ones if we could. “Few people,” he notes, “believe the world would be worse if there had always been fewer species of birds, and few would think it important to engineer new bird species if that were possible. What we believe important is not that there be any particular number of species but that a species that now exists not be extinguished by us.”

The intrinsic value of individual species is thus quite distinct from the value of species diversity. It also seems to follow from Dworkin’s claims that the loss involved in the extinction of an existing species cannot be compensated for, either fully or perhaps even partially, by the coming-into-existence of a new species.

The basic issue, then, seems to be a conflict between values: prevention of suffering and preservation of animal species. It is relatively uncontroversial that suffering is intrinsically bad for those who experience it, even if occasionally it is also instrumentally good for them, as when it has the purifying, redemptive effects that Dostoyevsky’s characters so often crave. Nor is it controversial that the extinction of an animal species is normally instrumentally bad. It is bad for the individual members who die and bad for other individuals and species that depended on the existence of the species for their own well-being or survival. Yet the extinction of an animal species is not necessarily bad for its individual members. (To indulge in science fiction, suppose that a chemical might be introduced into their food supply that would induce sterility but also extend their longevity.) And the extinction of a carnivorous species could be instrumentally good for all those animals that would otherwise have been its prey. That simple fact is precisely what prompts the question whether it would be good if carnivorous species were to become extinct.

The conflict, therefore, must be between preventing suffering and respecting the alleged sacredness — or, as I would phrase it, the impersonal value — of carnivorous species. Again, the claim that suffering is bad for those who experience it and thus ought in general to be prevented when possible cannot be seriously doubted. Yet the idea that individual animal species have value in themselves is less obvious. What, after all, are species? According to Darwin, they “are merely artificial combinations made for convenience.” They are collections of individuals distinguished by biologists that shade into one another over time and sometimes blur together even among contemporaneous individuals, as in the case of ring species. There are no universally agreed criteria for their individuation. In practice, the most commonly invoked criterion is the capacity for interbreeding, yet this is well known to be imperfect and to entail intransitivities of classification when applied to ring species. Nor has it ever been satisfactorily explained why a special sort of value should inhere in a collection of individuals simply by virtue of their ability to produce fertile offspring. If it is good, as I think it is, that animal life should continue, then it is instrumentally good that some animals can breed with one another. But I can see no reason to suppose that donkeys, as a group, have a special impersonal value that mules lack.

Even if animal species did have impersonal value, it would not follow that they were irreplaceable. Since animals first appeared on earth, an indefinite number of species have become extinct while an indefinite number of new species have arisen. If the appearance of new species cannot make up for the extinction of others, and if the earth could not simultaneously sustain all the species that have ever existed, it seems that it would have been better if the earliest species had never become extinct, with the consequence that the later ones would never have existed. But few of us, with our high regard for our own species, are likely to embrace that implication.

Here, then, is where matters stand thus far. It would be good to prevent the vast suffering and countless violent deaths caused by predation. There is therefore one reason to think that it would be instrumentally good if predatory animal species were to become extinct and be replaced by new herbivorous species, provided that this could occur without ecological upheaval involving more harm than would be prevented by the end of predation. The claim that existing animal species are sacred or irreplaceable is subverted by the moral irrelevance of the criteria for individuating animal species. I am therefore inclined to embrace the heretical conclusion that we have reason to desire the extinction of all carnivorous species, and I await the usual fate of heretics when this article is opened to comment.

(Jeff McMahan’s essay is the subject of this week’s forum discussion among the humanists and scientists at On the Human, a project of the National Humanities Center.)

Jeff McMahan is professor of philosophy at Rutgers University and a visiting research collaborator at the Center for Human Values at Princeton University. He is the author of many works on ethics and political philosophy, including “The Ethics of Killing: Problems at the Margins of Life” and “Killing in War.”