Steve Stewart-Williams Ph.D.

The Nature-Nurture-Nietzsche Blog

Rewriting Morality III: How Should We Treat Animals?

After Darwin, how should we treat other animals?

Posted Jul 10, 2010

This is the third and final post dealing with the implications of evolutionary theory for our traditional moral beliefs and practices (see Rewriting Morality I and Rewriting Morality II). In this installment, we'll look at the question of the proper treatment of nonhuman animals in the light of Darwin's theory.

As I argued in my first post, traditional moral systems are undergirded by a view known as the doctrine of human dignity. The central tenet of this doctrine is the idea that human life is sacred - that it has supreme worth and infinite value. The flipside of the doctrine of human dignity is the idea that all other animals occupy a lowly ranking on the scale of life. Saint Thomas Aquinas expressed this view when he suggested that animals exist for the sake of humans, not for their own sake, and thus that ‘It is not wrong for man to make use of them, either by killing or in any other way whatsoever'.

This is a sentiment many people have lived by. Historically, and even today, we have treated other animals abysmally. This is one of my favourite quotations; it comes from the Reverend W. R. Inge:

"We have enslaved the rest of the animal creation, and have treated our distant cousins in fur and feathers so badly that beyond doubt, if they were able to formulate a religion, they would depict the Devil in human form."

A number of commentators have gone so far as to liken our treatment of the animals to the Nazi Holocaust. Here's another quotation, this one from the author Isaac Bashevis Singer:

"They have convinced themselves that man, the worst transgressor of all the species, is the crown of creation. All other creatures were created merely to provide him with food, pelts, to be tormented, exterminated. In relation to them, all people are Nazis; for the animals it is an eternal Treblinka [a Nazi extermination camp]."

Let's now look at what an evolutionary perspective contributes to the debate. First and foremost, evolutionary theory challenges the doctrine of human dignity. As we've seen, Darwin's theory undermines the idea that we were made in the image of God, and it undermines the idea that we are distinguished in any morally significant way from the other animals by our possession of the faculty of reason. Moreover, it undermines the brute distinction between human beings and all other life, a central element of the doctrine. It does this by stressing our common origin and our kinship with the animals. Chimpanzees, dolphins, frogs - Darwin taught us that these are literally our distant relatives. Certainly, it is easy enough in practice to draw a human/animal distinction, and to import this into our moral reasoning. But evolutionary theory shows that this distinction has none of the significance it was once assumed to have. As such, its application in the moral sphere - that is, our habit of extending our moral concern only as far as the outskirts of our own species - suddenly starts to look arbitrary and unjustified. Why should our moral circle be limited to our species rather than to, say, our taxonomic class (i.e., mammals)? Why, for that matter, should it be limited to our species rather than to the racial group we belong to?

Evolutionary theory also undercuts a number of other arguments aimed at justifying the exploitation of animals. This includes the argument that God put the animals here for our sake. Before scientists pieced together a picture of the history of life on earth, this might have seemed like a reasonable claim. It's not reasonable anymore. We know now that the vast majority of animals finished their sojourn on this planet long before we evolved. We also know that we and the other animals came about through the same natural process, and that our so-called ‘creator' (i.e., natural selection) had no special affection for us. In light of these facts, the suggestion that animals are here for our use seems self-centred, quaint, and - to be clear about this - patently false. As the Pulitzer Prize-winning author Alice Walker wrote, nonhuman animals ‘were not made for humans any more than black people were made for whites or women for men'.

Another traditional justification for the exploitation of other animals comes from the Cartesian view that nonhuman animals are merely nonconscious automata, and thus that we need not worry that the way we treat them could cause them any suffering. But an evolutionary perspective drastically lowers our confidence in this view; after all, we are conscious beings (conscious automata perhaps), and we came about through the same process as every other animal. This being the case, it seems unreasonable to deny that any species other than our own is conscious or has the capacity to suffer, especially in the case of those animals that have very similar brains to our own.

And this brings us to a crucial point. If we decide - and this is our decision; it's not imposed on us from above - if we decide that reducing the amount of suffering in the world is a good ethical principle to live by, then it seems unwarranted and ultimately arbitrary to extend this principle to human beings but not also to extend it to other animals capable of suffering. Why should the suffering of nonhumans be less important than that of humans? Surely a universe with less suffering is better than one with more, regardless of whether the locus of suffering is a human being or not, a rational being or not, a member of the moral community or not. Suffering is suffering, and these other variables are morally irrelevant.

Of course, this is not to imply that all animals should be treated equally; no one would accept that the life of an ant is as important as the life of a human or a chimpanzee, or that swatting a fly should be considered an act of murder. But if we take the reduction of suffering as the foundation stone of our moral system, we may find a principled solution to this conundrum. The solution is to accord animals moral status in proportion to their degree of sentience or their capacity to suffer. Think about it. Why do we consider it morally repugnant to torture human beings? It's not because they're capable of language or rational thought, or because they're embedded in a social network of reciprocal rights and duties, or because they're members of our own species. It's because it causes them pain and trauma. If it didn't, we wouldn't worry about it. Of course, there is no ultimate justifaction for adopting the reduction of suffering as the basis of our morality. It comes down to a choice. I don't know about you, though, but I'd prefer to live in a world with less suffering than with more. I'd also prefer to live in a world where the ascendent moral principle is "reduce unnecessary suffering" than one in which it is "only be nice to creatures who can return the favour, or who can talk, or who happen to have the same kind of genome as you".

With the reduction of suffering as our guiding principle, we now have a solid and sensible rationale for many of our core ethical intuitions. Humans have a far greater capacity to suffer than flies; therefore, it is far worse to harm a human than to harm a fly. Similarly, humans presumably have a greater capacity to suffer than chimpanzees - we are locked into tighter emotional bonds, we grieve for longer - and therefore it is somewhat worse to harm a human than a chimp.

A lot of people would happily go along with me this far. However, this approach to morality also has some implications that many will find hard to swallow. For a start, if we accept that moral worth should be apportioned on the basis of the capacity to suffer, we would also have to accept that it would be worse to harm a member of a hypothetical species with a greater capacity to suffer than us than it would be to harm a human. For a more down-to-earth example, we need look no further than the work of the Australian bioethicist Peter Singer. Singer has argued, for instance, that the life of an anencephalic human infant (an infant born with little or no cerebral cortex) is worth less than the life of a healthy adult chimpanzee, or even a healthy dog, and that it would therefore be worse to kill or experiment on the chimp or the dog than it would be the infant. This is because the infant doesn't experience pain (or anything else), whereas the chimp and dog do. Such a view is utterly incompatible with the doctrine of human dignity, and if this view seems wrong to you, presumably this is because that pre-Darwinian moral outlook is still operative in your thinking. But can you justify it?

Once we accord nonhuman animals the moral standing they deserve, our relationship with them is transformed. For one thing, we recognize that prejudice and discrimination against other species (speciesism) is just as morally abhorrent as any other form of prejudice and discrimination, including racism and sexism. Indeed, Singer has made the extremely interesting and challenging point that the amount of suffering and pain caused by the tyranny of human beings over other animals (particularly in food production) far exceeds that caused by sexism, racism, or any other existing form of discrimination, and that for this reason, the animal liberation movement is the most important liberation movement in the world today. A moral system anchored in evolutionary theory is entirely consistent with this position. Women and disadvantaged ethnic groups have never been farmed, killed for sport, or systematically experimented on in anything like the numbers that nonhuman animals have. Furthermore, unlike women and slaves, nonhumans cannot talk or campaign for their own liberation, and, because they can't vote, they're not a high priority for most politicians. This further underscores the importance of the animal liberation movement.

None of the ethical conclusions we've surveyed in this post, or in the earlier post on suicide and euthanasia, are logically necessary implications of evolutionary theory, and it is certainly not the case that everyone who accepts the theory accepts these ideas. The reason evolutionary theory is important is that these kinds of ideas would be virtually unthinkable from a pre-Darwinian standpoint. Darwin shows us, if nothing else, that the ideas should be thinkable. His theory opens up the floor for debate on these issues, freed from the dogma that human life is infinitely valuable whereas the lives of nonhuman animals are utterly devoid of any value.

-For a more detailed discussion of this and related issues, see Darwin, God and the Meaning of Life by Steve Stewart-Williams - available now from,, and

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