‘It is to be observed, in the second place, that the obligation, as a general rule, to respect possession and promises, admits of being clearly shewn by reference to the consequences of actions taken as species and classes.’ Alexander Smith: The Philosophy of Morals.

Once upon a time I wrote a paper in which I defended a version of utilitarianism. This paper has received a certain amount of attention, but, I think, not as much individual attention as it might have done, had it not been confused with another version of utilitarianism, which became prevalent at about that time. This second version of utilitarianism came quite quickly to be known as rule utilitarianism. It has engendered a considerable amount of interest, so much so that it seems to me to be very likely that philosophers, who are utilitarians at all, are nowadays more likely to be rule utilitarians than they are to be ordinary act utilitarians.