In response to:

A Peopled Wilderness from the December 8, 2022 issue

To the Editors:

In “A Peopled Wilderness,” Martha Nussbaum notes that humans can “support the lives of animals,” and one tool she mentions is “spraying for tsetse flies” [NYR, December 8, 2022]. The spraying does not support the lives of the flies, of course, and for me this raises a question on which I would like to hear her always-astute analysis. When a human action benefits one species but hurts another, what are the philosophical grounds on which we can decide whether it is right or not?

Perry Link
Riverside, California

To the Editors:

Martha Nussbaum’s support for creating a better world for animals is, in my opinion, to be applauded. I feel, however, that two of her premises are wrong and that her big recommendation is deeply mistaken. Let me explain.

Her first mistaken proposition is that, citing John Stuart Mill, “Nature is cruel and thoughtless.” With all due respect to Mill and Nussbaum, this is false. To the extent that one can assign a personality to something as abstract and huge as “Nature,” a more accurate characterization would be “indifferent and thoughtless.” Cruelty takes intention and the wish to do harm. When it comes to sadism and cruelty, no pride of lions hunting gazelles for food has a patch on what humans regularly do to other humans through sociopathy and psychopathy. (Examples supplied on request.) Yes, individual animals die from hunger, disease, and predation, but that is also true for people in many human societies or poverty-stricken sections of those societies, both rural and urban. Why assert that Nature is uniquely harsh in this respect?

The second flawed assumption of the article is that the survival of so many animal species is dependent on humans. Really?? The examples that Nussbaum gives all involve animals whose survival as species or large subgroups was first put at risk by human activities, whether deliberately or as collateral damage from such activities. What most vertebrate species need for their survival is large areas of basically untouched environment where they can live. It is not out of sheer whim that several prominent biological scientists are arguing that 30–50 percent of our planet needs to be left free of human interference, both from direct habitat destruction and (one hopes) from climate change.

Finally, in this article, Nussbaum focuses on predation in the wild as needing to be controlled to provide a better life for “animals.” Nussbaum is totally correct in saying that the early-nineteenth-century Romantics overidealized Nature and its gentleness. Yet her view is essentially that of “Nature red in tooth and claw,” a late-nineteenth-century view that is just as false. I speak as a biologist who has spent much time in the wilds and can attest to the fact that most of the time, animals are going about their business peacefully. If they could not do so, they would be in perpetual physiological stress mode, which would kill them. And her view treats “predators” not as animals entitled to their own lives but as bad guys who need to be rehabilitated. I cannot imagine any biologist adapting this point of view; I most certainly do not.

Just one last point: had animals not evolved predation as a way of life, initially about 540 million years ago, animal evolution would have plateaued at a far simpler level of existence than what we have today. As one consequence, Nussbaum and I, as relatively advanced animal forms, would not be here to debate these issues!

Adam S. Wilkins
Visiting Scientist
Institute of Biology
Humboldt Universität zu Berlin

Martha C. Nussbaum replies:

Perry Link raises a fundamentally important issue: What should we do when two moral imperatives collide? As it happens, this question has fascinated me since the very beginning of my career, with my early work on ancient Greek tragedies, which pose that question in a stark fashion, unrelieved by optimistic philosophical emendation. I argue in The Fragility of Goodness (1986) and in subsequent articles (especially “The Costs of Tragedy: Some Moral Limits of Cost-Benefit Analysis,” in Cost-Benefit Analysis: Legal, Economic, and Philosophical Perspectives (2001), edited by Matthew D. Adler and Eric A. Posner) that the first thing we must do in such a situation is to face the issue, rather than to pretend that we are faced with a mere question of where the balance of costs and benefits lies. No, there is a further question: Do both available alternatives involve doing wrong?

If the answer to that question, which I call the “tragic question,” is yes, as when Agamemnon cries out, “Which of these is without evils?,” we must proceed as best we can in the moment, inflicting the least possible harm (for example, killing one person rather than the entire army, as was Agamemnon’s unhappy choice), but acknowledge, at the same time, that this choice saddles us with a terrible guilt that cannot be completely assuaged, even by reparations to the losing side. But then, following the philosopher Hegel in his wonderful remarks about Greek tragedy, we should also, and especially, look to the future, asking how we may envisage, and try to produce, a world in which nobody is faced with such a terrible choice. Hegel’s example was that the modern liberal state has to a great extent removed the tragic dilemma of Sophocles’ Antigone—where Antigone must choose between her religious obligations and her own life—by creating laws that protect people in the due exercise of their important religious duties.


Link’s example, killing tsetse flies to save sentient animals, is not, in my view, a tragic choice, because I believe insects are not sentient. I spend chapter 6 of Justice for Animals: Our Collective Responsibility investigating recent scientific research on sentience, and I then argue, first, that sentience is a minimum necessary condition for being a subject of justice, and, second, that it is not unjust to kill nonsentient beings (including insects and plants)—although we should still attend to their ecological importance in other ways. But there are many cases that are genuinely tragic for my analysis, and I devote an entire chapter to them. One example is the use of sentient animals in experimental research, which has great benefits for both humans and other animals, but inflicts ethically objectionable harms on animals. Here my Hegelian solution is to proceed as rapidly as possible toward a time when beneficial research can be done without harm to sentient beings, through the use of computer simulation and other technologies. Animal research is agreed to be rather unreliable anyway, and scientists are already moving in my Hegelian direction. I hope Link will enjoy the treatment of other tragic cases in my chapter.

Adam Wilkins’s letter shows how difficult it is to understand the arguments of a twelve-chapter book after reading a brief excerpt assembled from parts of its tenth chapter with a few brief passages from the first chapter, for he misunderstands me on several points. First, neither I nor J.S. Mill, whom I quote and greatly admire, means to impute moral wrongdoing to “Nature.” I teach Mill regularly to undergraduates and graduates, who get to know him well, and they know that Mill was an atheist (indeed, denied academic employment on that account), and that his essay “Nature” was satirical in intent. His opponents (Christian moralists of whom William Whewell, whose views about animals I discuss in chapter 3, is a salient example) believed in a Nature ordered by divine teleology, and what Mill is saying is: this “Nature,” this providential divine entity that you believe in (but I do not) is not beneficent, as you claim, but actually (if such an anthropomorphic deity existed) quite cruel. He is making fun of a view of the world that imputes divine will to an order that is, as Wilkins correctly says, indifferent to the wishes of all animals, human and nonhuman alike.

I suppose I might have asked the editors to allow me to explain at some length, within the excerpt itself, what Mill thought and what the intention of his essay was, but, having introduced Mill’s debate with Whewell in chapter 3 and criticized traditional religious anthropocentric visions of the natural world in chapter 2—and accustomed to philosophy students, to whom Mill’s ideas are well known—I allowed the excerpt chosen by the editors to go forward. Clearly this led to misunderstanding.

Wilkins places “animals” in scare quotes when alluding to my views about the damage humans do to nonhuman animals, as if to suggest that I do not realize that humans are also animals. However, I say at the very start of my book that, like most philosophers who write on the ethics of animal treatment, I will use the term “animal” as a shorthand for “nonhuman animal,” though fully and emphatically affirming that humans are animals. I also drew attention to the fact that since my doctoral dissertation on Aristotle in 1975 I have emphasized the common animality of all animals, human and nonhuman. So that is a second misunderstanding, clearly occasioned by the excerpt.

The next misunderstanding is the claim that I “assume” that the survival of animal species is dependent on humans. Actually, however, this is not an assumption but the conclusion of arguments previously presented, which could not possibly be summarized in a brief excerpt. By chapter 10 I have established by argument that humans are in control in all the spheres in which animals live: land, sea, and air. This was not always the case, but it is so now. Therefore, if animal species are to survive they will not do so without engaging the will and actions of this controlling power.


Not all the difficulties animals currently face are caused by humans, though most of them are. But if humans want to stop the accelerating rate of species loss, humans must act, since we hold all the power. (I should mention that my book focuses on injustice to individual sentient creatures, not on species—I don’t think a species is the sort of thing that can be unjustly treated. But the survival of a species is typically necessary for the flourishing of its members.) When Wilkins says that some scientists would like to see 30–50 percent of our planet left free of human interference, this strikes me as a contradiction in terms: For how would that 30–50 percent be freed up but through a massive project of human interference (including, inter alia, control over human fertility on a large scale)?

Then there is a further question: Given that we are in control, should we do just enough to stave off extinction (already a huge demand), or should we also actively assist animals that are beset by various obstacles? I point out that we already actively assist animals in many ways—not only our companion animals (the subject of the chapter just before this one), but also animals in so-called wild spaces that are actually controlled and curated by humans—spraying for tsetse flies, etc. Animal scientists perform surgeries on injured tigers and elephants, aid in the rearing of young who have lost their parents, rescue animals whose region is beset by droughts and floods, and move them to other places, and in many other ways intervene to preserve life and health. They typically do so in order to restore the creature to a life within its own animal group, and this is what I support.

I then get to the question of predation: Should we intervene there? My answer is not the crude one given by Wilkins—a fourth misunderstanding, in this case not caused by the excerpt format. My answer is nuanced. I reject the view (suggested by another philosopher) that we should engineer the extinction of predatory species. I then point out that in our homes and cities we do impose limits on animal predation through education and substitute activities, teaching a domestic cat to prefer balls and scratching posts to the killing of little birds, training a dog breed that could be predatory not to activate those skills (well-trained pit bulls), training our children to prefer sports to armed combat (though perhaps that is not what today’s American parents are actually teaching!). When we do this we do so in the belief that the creatures so trained will actually have better lives, and will not suffer agony from not becoming predators.

In the “wild,” it is evident that our knowledge is minimal and that we have no real idea how far the predatory instincts of a tiger or an eagle might be truly satisfied by a substitute activity. So my conclusion is, first, that we should recognize the problem as a problem: contrary to what some neo-Aristotelian philosophers say, a gazelle’s telos or goal is to live its life, not to be eaten by a predator. And, second, that we should interfere, if we do, only at the margins, and with great caution. My example is that we ought to stop making money out of what I call “sado-tourism,” the staging of predation for eager ecotourists by artificially propping up predator numbers. Nowhere do I treat predatory animals as “bad guys” (apart from the human ones); but they do cause lethal and painful harms. So if there should turn out to be ways of avoiding those harms, as there clearly are with companion animals and young humans, we should contemplate trying them—but do nothing now, or nothing much, because we are woefully ignorant.

Above all, we should continue learning and thinking, so I am grateful to these two readers for provoking a debate that I hope has been helpful.