Kip has replied to my post Why consider all desires that exist? which was a response to some emailed questions from him. There are three parts to his reply and I will only address the last part in this post, which is the most important issue.
Group A may have very many prudential reasons for ignoring the desires of Group B -- or perhaps they just don't have any prudential reasons to consider the desires of Group B. In other words, none of their desires will be fulfilled by considering the desires of Group B. Or, perhaps even, more of their desires will be thwarted by considering the desires of Group B.
So, without begging the question, why should Group A consider the desires of Group B, if 1) more of their desires will be fulfilled by not considering them, and 2) Group B has no way of influencing the desires of Group A (though force or social tools).
The impression is that Kip considers this an objection to (at least some aspect of) Desirism but this is no objection at all.
Consider, that for the above situation, anyone and everyone who has any moral theory in the world agrees with the desirist analysis (whether they are aware of it or not).
That is moral realists, desire-based or otherwise, reductive and non-reductive naturalists and non-natural intuitionists all agree. Normatively consequentialists, utilitarian and non-utilitarian, deontologists (duty-based ethics) and aretists (virtue-based ethicists) all agree to the same conclusion too. Similarly subjectivists, including divine command theorists might agree. And non-cognitivists too, whether of the emotive, expressive or universally prescriptive variety also agree.
The issue of inter-theoretical disagreement, that one group’s reasoning to the right conclusion in this situation is no guarantee that their (claimed) fallacious reasoning might work in others is not relevant. Nor too is any dispute over whether there are objective grounds or not to come to this conclusion. Subjectivists agree regardless.
Now Group A in defence – if they ever hear or allow such criticisms of their position – might answer as moral nihilists – hence any such criticism have no force. Or they they might take the position of normative relativists – this is the way we do things here and no-one else has any grounds to judge them otherwise. Or, more likely they prevent – suppress, censor and hide -such criticism and basically ignore them.
What then? The whole world agrees that Group A’s practices are “wrong”, their values are “bad”, they “should not” continue as they are.
The world can try and use the social forces of condemnation – published and vocal criticism of Group A in the media and the internet - and social punishment such as refusing to buy from them or through more formal trade sanctions... and still Group A can belligerently carry on and choose to isolate themselves from the rest of the world.
At this point the issue is beyond morality per se and to do with international law (if that can even be said to exist), just war and so on. Now there are ethical issues underlying these but they are different now to the original challenge posed by Kip.
One can all too easily think of international examples that do conform to the above – although people might very well disagree over the examples e.g. The first Iraq War had a large amount of cross-cultural agreement, the latest Afghanistan far less so and that second Iraq War it was virtually non-existent. But feel free to disagree such a characterisation as just presented.
The point is what action is to be taken or actions to refrain from taking are beyond the type of moral considerations here. Yes there are different moral issues over further actions but that is a different issue to the question that Kip asked and I answered.
So this is not an objection to desirism, rather it is an objection that could be raised against any and all ethical analysis of the relation between Group A and Group B. That is the issue is nothing specific to Desirism per se. It is part and parcel of the inherent limitations of any institution of morality.
One of the challenges of the institutions of morality is to create a world where Group A/Group B situations do not occur, where they are inhibited and discouraged from occurring in the first place, where such scenarios are prevented. That is an ongoing effort and one of the reasons why searching for the provisionally best ethical models is worthwhile and important, to help make the world a better place for everyone.