If by “moral-utility realism” you mean the notion that there is one true moral utility function that everyone should use, I think that’s what you’ll find in the writings of Bentham, and of Nozick. Not explicitly asserted; just assumed, out of lack of awareness that there’s any alternative. I haven’t read Nozick, just summaries of him.
Historically, utilitarianism was seen as radical for proposing that happiness could by itself be the sole criterion for an ethical system, and for being strictly consequentialist. I don’t know when the first person proposed that it makes sense to talk about different people having different utility functions. You could argue it was Nietzsche, but he meant that people could have dramatically opposite value systems that are necessarily at war with each other, which is different from saying that people in a single society can use different utility functions.
(What counts as a “different” belief, BTW, depends on the representational system you use, particularly WRT quasi-indexicals.)
Anyway, that’s no longer a useful way to define utilitarianism, because we can use “consequentialism” for consequentialism, and happiness turns out to just be a magical word, like “God”, that you pretend the answers are hidden inside of.
If by “moral-utility realism” you mean the notion that there is one true moral utility function that everyone should use, I think that’s what you’ll find in the writings of Bentham, and of Nozick. Not explicitly asserted; just assumed, out of lack of awareness that there’s any alternative. I haven’t read Nozick, just summaries of him.
Historically, utilitarianism was seen as radical for proposing that happiness could by itself be the sole criterion for an ethical system, and for being strictly consequentialist. I don’t know when the first person proposed that it makes sense to talk about different people having different utility functions. You could argue it was Nietzsche, but he meant that people could have dramatically opposite value systems that are necessarily at war with each other, which is different from saying that people in a single society can use different utility functions.
(What counts as a “different” belief, BTW, depends on the representational system you use, particularly WRT quasi-indexicals.)
Anyway, that’s no longer a useful way to define utilitarianism, because we can use “consequentialism” for consequentialism, and happiness turns out to just be a magical word, like “God”, that you pretend the answers are hidden inside of.