...what the principle of utility requires of me is to do for each man affected by my actions what I wish were done for me in the hypothetical circums… - R. M. Hare

I had a strange dream, or half-waking vision, not long ago. I found myself at the top of a mountain in the mist, feeling very pleased with myself, not just for having climbed the mountain, but for having achieved my life’s ambition, to find a way of answering moral questions rationally. But as I was preening myself on this achievement, the mist began to clear, and I saw that I was surrounded on the mountain top by the graves of all those other philosophers, great and small, who had had the same ambition, and thought they had achieved it. And I have come to see, reflecting on my dream, that, ever since, the hard-working philosophical worms had been nibbling away at their systems and showing that the achievement was an illusion.

The rules of moral reasoning are, basically, two, corresponding to the two features of moral judgment...When we are trying, in a concrete case, to decide what we ought to do, what we are looking for...is an action to which we can commit ourselves (prescriptively) but which we are at the same time prepared to accept as exemplifying a principle of action to be prescribed for others in like circumstances (universalizability)...[I]f we cannot universalize the principle, it cannot become an ‘ought’.

It is said that the prescription to keep all black people in subjection is formally universal, and internally consistent, and so is not ruled out by the Categorical Imperative. But the point is: can somebody who has fully represented to himself the situation of black people who are kept in subjection go on willing that they should be so treated? For if he has fully represented this to himself, he will have formed a preference that he should not be so treated if he is a black person; and this is inconsistent with the universal form of the proposed maxim. There is of course the problem of the fanatical black-hater who is prepared to prescribe that the maxim should be followed even if he himself were a black person. I have discussed the case of this fanatic at length in my books...and I think I have shown that my theory can deal with him. At any rate the Kantian move can be used in arguments with ordinary non‐fanatical people.