It is widely admitted that moral judgments are universalizable, but whether this universalizability is formal or subjective is still in controversy. In this paper, I will investigate R.M.Hare’s argument for the formality of the universalizability. It is often said that his attempt fails because he derives a subjective moral conclusion like utilitarianism from that principle. However, Hare does not derive the moral conclusion from universalizability alone. Rather, what attaches morality to Hare’s utilitarianism is the concept of prescriptivity and rationality, not universalizability. In conclusion, I will vindicate Hare’s theory, but at the same time point out a problem of the normativity of rationality that is included in his theory.
