Your dinner in February of 2017. Photo: Anopdesignstock

If you ask a meat eater, “Which meat is okay to eat, and why?” most people will at least attempt to form a coherent answer couched in moral language. They’ll attempt to defend their own decisions, in other words, on some rational basis.

But as we know from piles and piles of research into moral psychology, people hold many moral beliefs not for rational, easy-to-explain reasons, but rather for gut-level, intuitive, hard-to-explain ones. When it comes to our morality, we are frequently post-facto rationalizers. We act as though we carefully deliberated and came to this or that conclusion, but really the process works in reverse. We develop a moral belief for whatever reason, and then build a rationalization around it, like some pretty but flimsy facade. (There are obviously exceptions to this; people plainly evolve in their moral thinking, and there’s no shortage of controversy on what “rational” even means in many moral contexts.)

For meat eaters, a common rationalization has to do with intelligence: Many meat eaters say they eat dumb animals, but not smart ones, in part because dumb animals don’t enjoy the same moral standing as higher forms of life — dumb animals can’t think and feel and ponder and suffer the way we can. For carnivores taking this tack, pigs are an inconvenient truth: They are as smart as dogs, and yet most Americans who eat pigs would never eat a dog. (In parts of China and elsewhere, dog meat is savored.) If you argue that intelligence is the benchmark you use to decide which animals to eat, it doesn’t make logical sense to say that it’s morally permissible to eat pigs but not dogs. And yet a lot of people do argue that, or something like it.

A new study in Social Psychological and Personality Science by Jared Piazza of Lancaster University and Steve Loughnan of the University of Edinburgh (both in the United Kingdom) attempts to better understand what’s going on when people defend their dietary habits by pointing to the intelligence of the animals they do and don’t eat, and how they wriggle out of certain hard truths about pigs and other not-dumb sources of meat.

The authors explain that they went in expecting that the participants in their three experiments would engage in a bit of motivated reasoning: that is, accepting and rejecting evidence based not on its strength, but on whether it supports a preexisting belief or behavior. Past work on this front, after all, “has shown that people alter their judgment of animal intelligence to be in line with their actions, for example, when they are made aware that eating animals is inconsistent with the animal’s moral standing[.]” Generally speaking, in other words, meat eaters are more likely to change our interpretation of the situation — naw, pigs aren’t actually that smart — than change their behavior. Their reasoning is, well, motivated. (Motivated reasoning is a human universal — I’m not meaning to suggest it applies only to meat eaters.)

In the first experiment, the researchers wanted to test their intuitive-seeming hypothesis that people really do claim to use intelligence as one of the ways they decide which species are fair game to eat. So they had 59 Amazon Mechanical Turk workers read a prompt about a distant-future scenario in which scientists discover a species called “trablans” on another planet. “All participants read that the trablans possessed some ‘filler’ characteristics (i.e., group living, herbivores),” the authors write. Then, the participants were informed about the trablans’ intelligence levels: Half the Turkers were told trablans exhibited “sophisticated problem-solving abilities, including tool use. Trablans can learn simple rules and memorize pattern sequences to get food.” The other half were told that trablans are, well, maybe not the most intellectually gifted alien species in the galaxy.

Then the participants were told that the scientists were considering eating the trablans — not because they were starving or anything, but rather because it would allow them to stretch their food supply a bit — and were asked to rate, on a seven-point agree-disagree scale, several statements about the moral acceptability of doing so. Sure enough, the intelligence assessment appeared to matter a great deal: 93.5 percent of the Turkers said they were opposed to eating the trablans when they were high-intelligence, while 60.7 percent said they were against it when they were dumb.

In the second experiment, which was similar to the first, the researchers asked a group of Brits who reported eating pig products about pigs, tapirs (which are eaten in other parts of the world, but not in the U.K.), and the aforementioned trablans. As in the previous experiment, the researchers randomized whether the animals were described as high- or low-intelligence. The respondents were then asked how much “moral standing” the animals had, on a 100-point scale. As it turned out, descriptions of high intelligence only led to higher moral standing when it came to the tapirs and trablans — that is, the animals those in the sample weren’t already accustomed to viewing as food.

In the third experiment, also conducted with a British sample of pig-eaters, half the participants read material about how dogs are more intelligent than pigs, while the other half read the reverse — pigs are more intelligent than dogs. Now, half the participants simply read that material, while the other half were told to imagine John, a different person, reading that material, and to then anticipate his reactions to it. As in the other experiments, after reading the intelligence materials the respondents were asked how much moral standing they would grant to pigs.

The researchers found that when taking someone else’s perspective — that is, John’s — the high-versus-low intelligence divide mattered a great deal. Participants imagined that John would rate pigs as having much higher moral standing in the high-intelligence condition than the low-intelligence one. When the participants took their own perspective, “intelligence information did not significantly influence their judgments.” Statistically, they gave “smart” and “dumb” pigs about the same moral standing.

Overall, these results support the researchers’ hypothesis that people only fully factor in animal intelligence in a “motivated” manner — that is, when it serves their own behavior and beliefs. Intelligence is a straightforward-sounding way to justify decisions that, in many cases, were pressed on omnivores by their cultures, their childhood experiences, and whatever else (plus, meat tastes good). Again: We’d like to think that our decisions about which foods to eat and which to shun — and our other moral decisions — come from some sort of rational calculation, but that’s frequently false.