Gibbard uses the example to illustrate the possibility of fundamental moral disagreement – disagreement, that is, that is not based on someone’s confusion, irrationality, or ignorance or misapprehension of some relevant naturalistic fact. On Gibbard’s telling, we and the Hopi agree on all the “plain” naturalistc matters of fact, like whether the chicken feels pain. We just fundamentally disagree on what that implies for what to do.
The possibility of fundamental moral disagreement matters to the dispute between ethical expressivists (like Gibbard) and non-naturalist realists on one side and naturalist realists on the other. Naturalists have trouble explaining how genuine fundamental moral disagreement is possible. If moral naturalism is true, then it seems that the dispute between us and the Hopi can be settled in principle by further empirical investigation. For then moral properties would be natural properties, or at least reducible to them, in which case, if we learn enough about the natural world, our theory of it should entail the correct ethical theory. But that would show the disagreement not to be fundamental after all.
But this bit of philosophical folklore always seemed to me a little too neatly cut to be the whole truth, and being a moral naturalist myself, I have a vested interest in sussing out the complications. I’m particularly interested in two questions: whether Brandt uncovered strong evidence of a cultural fundamental moral disagreement on the treatment of animals, as Gibbard usually portrays it, and whether he found strong evidence of any fundamental moral disagreement on the treatment of animals, whether it’s properly cultural or not. (Edit: To be clear, I don't think that cultural fundamental disagreement is worse for naturalists than mere interpersonal fundamental disagreement. But it's my recollection that Gibbard usually presents the case as one of fundamental disagreement between cultures, and I think it's worth getting clear on whether Brandt shows this to be the case.)
Brandt died in 1997, so there is no following up with him on the story. But we do have his 1954 anthropological work on the Hopi, Hopi Ethics. I dug it out from the library recently, and this is what I found.
(Page references are to that work. Brandt contrasts Hopi beliefs with those of “white Americans”. Since the American culture I am familiar with is not exclusively white, I will write of non-First Nation Americans, or NFNAs, at least when not attributing views to Brandt.)
The apparent cruelty of the Hopi towards animals made a strong impression on Brandt, especially given some of their beliefs about animals’ psychology that would tend to make them more like humans rather than less (245). And it was indeed his conclusion that the Hopi’s treatment of animals showed there to be at least one fundamental ethical disagreement between them and white Americans (246). But was he right to draw this conclusion, at least given the evidence he presents in the book?
At the beginning of the section on treatment of animals – and in contrast to what Gibbard usually reports Brandt as holding – Brandt tells us that most Hopi hold that it is wrong to make anything suffer if it has not done anything wrong, animals included. In fact, he reports most Hopi as taking it as obvious that the feelings of animals are reasons to be kind to them. That's a significant reason to think that the Hopi really do think animals' pain as a reason not to harm them, and so that we don't disagree with them on this point after all. (The Hopi may be more willing to attribute wrongdoing to animals and punish them for it than we are, but this is not clear evidence of a fundamental moral disagreement. The Hopi appear to have different beliefs about animals’ mental lives than most NFNAs today.)
He does, however, present evidence in favor of the claim that some Hopi thought that animals’ pain itself was not a reason against mistreating them. One of his informants, A, liked playing chicken pull even though he thought that “animals have pain as much as human flesh” (215). Brandt also indicates that gratuitous cruelty to animals is common among the Hopi, such as allowing children to catch and “play” with birds that usually die. “Nobody objects to this,” he quotes an informant as saying. Sometimes animals are executed during dances, and he reports that once a dance audience was amused by the botched execution of a donkey. Interestingly, a number of informants hint that they find it significant that animals cannot speak or complain. So it is possible that these Hopi believe that a being’s pain is only a reason not to harm if it complains about it. That would be in disagreement with NFNA moral belief, I think.
But Brandt does not provide incontrovertible evidence of a fundamental moral disagreement between Hopi and NFNA culture. After all, most NFNAs believe that it’s ok to kill an animal just because you want to eat it, even if it has done nothing wrong and would suffer pain thereby. Many also think that it’s ok to take pleasure in killing animals, as in hunting. Perhaps some of these people also think that animals’ pain itself does not matter morally. If that’s so then the actuality of fundamental moral disagreement is more interpersonal than intercultural, and it is misleading to illustrate it with a supposed cultural difference.
But I reckon it more likely that hunters and animal-eaters generally agree that animals’ pain is a reason not to kill them even when they are killed for sport or food, but also think it not a very strong one, or at least it is simply not one they care about very much. At least that is what I thought back when I was a meat-eater! Given that most Hopi told Brandt that they thought animal suffering mattered morally, Brandt's story gives us some reason to think that the Hopi thought of animal suffering as a reason not to harm them, albeit a weak one or one that did not motivate them.
Put simply, a plausible alternative to the relativistic hypothesis – the thesis that there is fundamental moral disagreement between some of the Hopi and most of us NFNAs on whether all pain is a reason not to harm – is the hypothesis that the Hopi who were cruel to animals believed that it was wrong to hurt animals, but manifested the same kind of divergence between ethical ideals and actual behavior that is rampant in human societies; their divergence on this point is simply greater than you would expect among NFNAs. Brandt's interviews don't seem to me to favor one hypothesis over the other. I conclude that Brandt’s interviews don’t provide strong evidence that some among the Hopi thought that suffering itself was not a reason not to harm, nor that there is fundamental moral disagreement.
I’ve posted a scan of the relevant bit from Brandt’s Hopi Ethics here. It’s fascinating stuff.