The Argument from Speciesism
If there is some doubt whether the arguments from monkeys and from glass walls should be considered moral arguments, there can be no doubt about the moral import of the argument from speciesism. According to this argument, the view that eating the meat of nonhuman animals is morally permissible but eating the meat of human beings is morally forbidden is analogous to racism or sexism. Just as racism and sexism are to be morally condemned, so is speciesism. Although there are differences between races and sexes, there are no morally relevant differences that justify differences in treatment. Similarly, although there are differences between human beings and other animals, there are no moral differences that justify human beings’ killing and eating animals but not killing and eating one another. Moreover, since it is morally wrong to kill and eat human beings, it is morally wrong to kill and eat animals.
KBJ: Martin is right that this is a moral argument.
This argument of the vegetarian has a point. Animal species per se is not a morally relevant distinction. Consequently, nonvegetarians are not on firm ground if they justify killing and eating animals simply on the ground that the animals are not humans. On the other hand, the animal kingdom per se (in contrast to particular animal species) does not provide any morally relevant grounds for the positive content of vegetarianism. To suppose otherwise would be a form of kingdomism, no different in principle from the speciesism, racism, and sexism that this argument condemns. After all, what is the justification for eating plants and not animals? Is there a morally relevant difference between the two? The vegetarian, to make his case, must draw a line—a morally relevant line—between the plant kingdom and the animal kingdom. For this another argument is needed.
The argument usually provided by vegetarians to fill the void created by the argument from speciesism is this: Animals are sentient creatures; they feel pain and have other feelings. But no plant is sentient; no plant can see, hear, or feel. Consequently, it is wrong to eat animals but not wrong to eat plants.
Two questions can be raised about this argument from sentience. First, is it really true that plants feel no pain? The recent bestseller, The Secret Life of Plants, and other less well known studies may give us some pause. To be sure, most biologists have not taken the thesis of the mental life of plants seriously, and in the light of our present evidence they are undoubtedly justified. But what if new biological findings were to indicate that speculations about the mental life of plants should be taken seriously? Should we then stop eating plants as well as animals?
KBJ: If it turns out that plants are sentient (i.e., capable of suffering), then yes, it would follow that they matter, morally, because suffering is intrinsically bad. This doesn’t mean that we can’t continue to eat them; it means that if we do eat them, we wrong them. Sometimes there is no way to avoid wrongdoing. At present, fortunately, there is an alternative to eating animal flesh, namely, eating a plant-based diet. If plants turn out to be sentient, as Martin hypothesizes, then there would be no alternative to eating something sentient (unless we allow ourselves to starve). But surely plant sentience would be inferior to animal sentience, qualitatively speaking, in which case morality would require that we eat plants rather than animals. Even in Martin’s hypothetical world, therefore, it would be wrong to eat animals. (By the way, it’s at least as likely that Martin is not sentient as that plants are.)
Without new discoveries in synthetic food made from inorganic material, our refraining from eating plants would spell the end of the human species. But is species suicide really necessary? After all, why should the discovery that plants feel pain have any effect on whether we eat them or not? Presumably this discovery should have some effect on how we kill plants. If we knew that plants felt pain, our killing them would, or at least should, take a humane form. We might somehow anesthetize grain before it was harvested, and so on. But it is completely unclear why the knowledge that plants feel pain should prevent our eating them.
KBJ: Would Martin say the same thing about humans? Is it permissible to eat human flesh provided the human in question was painlessly killed? If not, why not? Once he answers this question, he will see that it applies to animals as well as humans.
This brings me to the second point. Even if animals but not plants feel pain, why should this make any difference to whether we eat animals or not? One would have thought that an animal’s ability to feel pain would be morally relevant, not to whether it should be killed and eaten, but to how it should be killed if it is to be eaten. Because animals feel pain they should not suffer. But so long as they are not made to suffer it is unclear what relevance their sentience has for vegetarians.
KBJ: Ditto. What Martin should explore is why it is wrong to eat human flesh. He will find that the explanation for this wrongness applies equally well to animals—but not to plants.