In a series of later books, Hare made moral supervenience, combined with the criterion that a rational being would prefer the satisfaction of his preferences over their frustration, the basis of his idea of universal prescriptivism. From this he derived a version of utilitarianism, by arguing that to prescribe a particular action in one's circumstances was only rational if you would prescribe anyone's else's doing it, even if you were equally likely to be any agent (including all those affected, for good or ill, by the action). This would only be true if, were you to personally experience all the good and bad effects of the action upon all affected persons (i.e., the satisfaction and frustration of their preferences), you would not prefer some other action to the one in question.Hare, 1963Hare, 1981 He often simply called moral supervenience "universalizability" and equated it with Kant's principle of universal law,Hare, 1963, p.219Hare, 1997, pp.151-153 although the two are not the same (see moral universalizability).
