There is a powerful argument that is frequently used in metaethics (and elsewhere). It’s based on the idea that disagreement requires shared concepts. Thus, by looking at who we can intuitively disagree with we can determine who we share our concepts with. And, in when it comes to morality, it seems we can disagree with people who classify very different things under moral terms. As a result, it is argued, ethical terms cannot have ‘descriptive content’. I used to think that this great argument works. Today I’m feeling less certain about this and I’d like to hear about your thoughts. Here is why.

One of the original formulations of the argument is from Hare 52 (as quoted in Smith 94) – the classic cannibal case:

Let us suppose that a missionary, armed with a grammar book, lands on a cannibal island. The vocabulary of his grammar book gives him the equivalent, in the cannibals’ language, of the English word ‘good’. Let us suppose that, by a strange coincidence, the word is ‘good’. And, let us suppose, also, that it really is equivalent – that it is, as the Oxford English Dictionary puts it, ‘the most general adjective of commendation’... If the missionary has mastered his vocabulary, he can, so long as he uses the word evaluatively and not descriptively, communicate with them quite happily. They know that when he uses the word he is commending the person or object that he applies it to. The only thing they find odd is that he applies it to such unexpected people, people who are meek and gentle and do not collect large quantities of scalps; whereas they themselves are accustomed to commend people who are bold and burly and collect more scalps than the average.

We thus have a situation which would appear paradoxical to someone who thought ‘good’ … was a quality word like ‘red’. Even if the qualities in people which the missionary commended had nothing in common with the qualities which the cannibals commended, yet they would both mean what the word ‘good’ meant. If good were like ‘red’, this would be impossible; for the cannibals’ word and the English word would not be synonymous... It is because in its primary evaluative meaning ‘good’ means neither of these things, but is in both languages the most general adjective of commendation, that the missionary can use it to teach the cannibals Christian morals.

I just love this passage. In any case, much after Hare’s argument, it seemed like some philosophers wanted to apply Putnam/Kripke natural-kind semantics to moral terms. Smith, Horgan and Timmons, and others then applied Hare’s argument against such attempts. On the new naturalist views, people’s referential intentions or their use of the term ‘good’ would fix the reference of ‘good’ to some natural property that would then constitute goodness is. Yet, the speakers can be quite unaware of what that property is, and this would explains the intuitions behind the open question arguments.

Unfortunately, it seems like we can imagine cases in which the reference gets fixed to slightly different natural properties in different communities. As a result, the content of the goodness claims in these communities will be different. We’ll be talking about what’s good (imagine, H 2 O) whereas they’ll be talking about what’s tgood (XYZ). This would mean that there would be no real disagreements but rather talking past one another. Yet, it seems intuitive, almost platitudinous, that when A says ‘x is right’ and B ‘x is not right’ in these cases they disagree (as Smith says) just as long as their terms play corresponding practical roles.

There is a naive answer to this argument. It says that people in the disagreement scenarios only think that they disagree substantially whereas in fact they really don’t as they have different concepts. And, it is easy to motivate why we would act as if we disagreed. This would be a way of getting the other party to adopt our concept. Given the practical role of the concepts, this would affect their behaviour. Some conceptual disagreements really are worth fighting for.

The defenders of the argument have a response to the naive answer. They say that to claim that there is no real disagreement would be chauvinistic conceptual relativism. On this view, part of the argument rests on our conceptual competence with the moral terms. The awareness of when one has a real substantial disagreement with others is part of that competence. This is why it is platitudinous that we would be disagreeing with the cannibals (as Smith puts it). And, it does seem offensive to be told that, despite what you honestly think, you aren’t really disagreeing about real moral issues. This would be to challenge your competence.

I used to think that this must be right. But, then I heard Stephen Yablo mention how our intuitions about whether our disagreements are substantial or conceptual are more than shaky. If this were right, then knowing when one is in a substantial disagreement would not necessarily be part of conceptual competence and the naive answer might be defended. Consider following kind of cases. Imagine that you go see a film with your teenage son. He buys a large bucket of popcorn. In this situation, it is easy to imagine that you could have a disagreement about whether that is a lot of popcorn (‘that’s a lot of popcorn’, ‘no it isn’t’ sounds natural). In this case, when you think of the situation philosophically, it is just as easy to think that the disagreement is merely a conceptual one. You and your son would clearly have different standards for what is a lot of popcorn and you are both saying something about the amount of popcorn relative to your standards. Yet, you can go on disagreeing. So, it does seem that the real disagreement here is about what is the standard of assessment to use in buying popcorn.

Thus, in a sense, you are disagreeing because you do have different concepts and this disagreement seems conceptual. It would also be hard to think that Hare’s argument shows in this case that ‘a lot’ does not have descriptive meaning. On the other hand, it doesn’t seem like when you put yourself in the situation you would describe yourself as having a disagreement about what ‘a lot’ means or which concept is the one use. The idea of making a semantic ascent within that situation itself seems odd even if that would be what really seems to be going on from the outside.

So, I’m starting wonder why the naturalist could not say something similar about the cannibal and twin-earth cases. The point would just be that it’s not part of our semantic competence as competent speakers to know whether we would be having substantial or conceptual disagreements. We don’t really care or need to care in real situations. If this were right, then the intuition that we would be having a disagreement would not be enough to show that we share the same concepts.