(For other posts in this series, see here.)

I wrote before that the theory of evolution, by giving all animals equal standing in the evolutionary tree of life, provides a strong argument against the exploitation of one sentient species by another. There seems to be no defensible criteria by which we can prefer the interests of an individual human over that of an individual nonhuman animal, because they each have an interest in avoiding pain and suffering.

This seems to imply that killing animals in order to obtain meat for eating is wrong under all circumstances. But in his book The Omnivore’s Dilemma (2006), Michael Pollan suggests that this need not necessarily follow.

The argument is a tricky one that involves disentangling the interests of a species from the interests of individual members of the species. Recall that it was argued that we could not and should not give preferential treatment to our species as a whole over other species as a whole because whatever marker we might use for doing so (intelligence, language, consciousness, etc.), we would find at least some individual members of our species who had less of that quality than some members of other species.

But if we keep the argument at the level of species, a case can be made for eating meat.

One argument says that if the human species as a whole possesses some significant quality (say intelligence or consciousness) that other species either do not possess or possess at a lower level, that entitles all members of the human species privileged treatment, even those who may possess less of that particular quality than some members of other species. In other words, this argument rejects entirely the premise of the argument from marginal cases. But this line of argument has significant consequences if applied within the human species. If, for example, we discovered some important quality that (say) females possessed on average more than males, would we then be willing to privilege all women over all men?

Another argument says that being domesticated for the purpose of being eaten or otherwise exploited by humans has benefited such species of animals. The domesticated species we eat (cows, pigs, chickens, etc.) would most likely become extinct if we ceased to eat them. After all, the reason that their numbers are much greater than their wild cousins is because they have benefited from the protection that humans have given them. At some point in evolutionary history, these animals showed signs of being amenable to living alongside humans, adapted to doing so, and as a result they have experienced an explosive growth in numbers.

“[D]omestication took place when a handful of especially opportunistic species discovered, through Darwinian trial and error, that they were more likely to survive and prosper in an alliance with humans than on their own. Humans provided the animals with food and protection in exchange for which the animals provided the humans their milk, eggs, and – yes – their flesh.” (Michael Pollan, The Omnivore’s Dilemma, p. 320) This language is somewhat misleading in that it implies that both sides were equal and conscious partners to this deal and that the animals voluntarily submitted. In fact, it is humans who unilaterally set the terms.

But as a result of this ‘bargain’, it is undoubtedly true that many of the animals we don’t eat like wolves, lions, and tigers are in danger of extinction, while dogs, cows, chickens, and pigs have flourished, at least in numbers. If we all became vegans and released domesticated animals into the wild, the numbers of these domesticated species would dramatically decrease and may even perish entirely within just a few generations.

The problem here is how to decide between what is good (at least numerically) for (say) the species of chicken (which favors domestication and the consequent meat eating) and what is good for an individual chicken (which clearly has an interest in not being eaten). The issue is further complicated by the question of whether the individual chicken has an interest in being born at all, if the price for that opportunity is to be killed and eaten later.

Answering such questions involve difficult, even impossible, metaphysical calculations. Is it better to have not lived at all or to have lived a good life even if that means being eventually killed to be eaten by others? Does the life of a single chicken that lives a long life result in more or less net happiness and suffering than two (or more) chickens whose lives are cut short? And so on.

Next: How do we weigh the benefits of a good life against a quick and painless but early death?

POST SCRIPT: This Modern World

Cartoonist Tom Tomorrow on stupidity in politics.