16 “Interests” basically means strong and legitimate preferences, which obviously require some degree of consciousness, responsiveness to stimuli, etc. See, for instance, the utilitarian philosopher Peter Singer, whose 1974 Animal Liberation is more or less the bible of the modern animal-rights movement: “It would be nonsense to say that it was not in the interests of a stone to be kicked along the road by a schoolboy. A stone does not have interests because it cannot suffer. Nothing that we can do to it could possibly make any difference to its welfare. A mouse, on the other hand, does have an interest in not being kicked along the road, because it will suffer if it is.”
17 This is the neurological term for special pain receptors that are (according to Jane A. Smith and Kenneth M. Boyd’s Lives in the Balance) “sensitive to potentially damaging extremes of temperature, to mechanical forces, and to chemical substances which are released when body tissues are damaged.”
18 “Preference” is maybe roughly synonymous with “interest,” but it is a better term for our purposes because it’s less abstractly philosophical—“preference” seems more personal, and it’s the whole idea of a living creature’s personal experience that’s at issue.
19 Of course, the most common sort of counterargument here would begin by objecting that “like best” is really just a metaphor, and a misleadingly anthropomorphic one at that. The counterarguer would posit that the lobster seeks to maintain a certain optimal ambient temperature out of nothing but unconscious instinct (with a similar explanation for the low-light affinities about to be mentioned in the main text). The thrust of such a counterargument will be that the lobster’s thrashings and clankings in the kettle express not unpreferred pain but involuntary reflexes, like your leg shooting out when the doctor hits your knee. Be advised that there are professional scientists, including many researchers who use animals in experiments, who hold to the view that nonhuman creatures have no real feelings at all, only “behaviors.” Be further advised that this view has a long history that goes all the way back to Descartes, although its modern support comes mostly from behaviorist psychology.
To these what-look-like-pain-are-really-only-reflexes counterarguments, however, there happen to be all sorts of scientific and pro-animal-rights countercounterarguments. And then further attempted rebuttals and redirects, and so on. Suffice to say that both the scientific and the philosophical arguments on either side of the animal-suffering issue are involved, abstruse, technical, often informed by self-interest or ideology, and in the end so totally inconclusive that as a practical matter, in the kitchen or restaurant, it all still seems to come down to individual conscience, going with (no pun) your gut.
20 Meaning a lot less important, apparently, since the moral comparison here is not the value of one human’s life vs. the value of one animal’s life, but rather the value of one animal’s life vs. the value of one human’s taste for a particular kind of protein. Even the most diehard carniphile will acknowledge that it’s possible to live and eat well without consuming animals.