A quick question about animal ethics. Presumably, the philosopher who responds to this would agree that if we were currently doing to humans what we do to animals in our food systems—that is, breeding and slaughtering them by the billions every year, not out of nutritional necessity, but for the sake of taste pleasure—that would be immoral. (I sure hope so!) So the question is: What is the trait absent in nonhuman animals that, if also absent in humans, would justify breeding and slaughtering humans by the billions for something as trivial as taste pleasure? The knee-jerk justification today’s nonvegans would give is that, relative to humans, animals have diminished mental capacities, and that mass confinement and slaughter is therefore acceptable. But surely intelligence can’t be the trait, because the same nonvegans would never dream of arguing that it’s okay to confine and slaughter a human being (let alone billions of them) just because he has a level of intelligence equivalent to that of a pig or cow. Neither can the missing trait be the ability to experience physical pain or psychological suffering, both of which, according to scientists like Jane Goodall, animals like cows, pigs, chickens (and yes, even fish!) evolved to do. So what is the trait? Or what are the traits? (Full disclosure: I do not believe the trait or group of traits exists.)