© Rhys Southan 2017


According to the metaethics of R. M. Hare, we determine morality objectively by making a moral judgment, committing to the moral principle underlying that judgment, and then logically extending that moral principle to all relevantly similar cases. This metaethical system called universal prescriptivism had a major impact on Peter Singer, whose arguments for radically improving animal welfare and alleviating global suffering frequently rely on Hare-ian appeals to logical consistency. Hare’s work in metaethics is largely rejected now, but Singer’s popularity has kept Hare’s prescriptivism alive through the many animal welfarists and effective altruists who have borrowed Singer’s style in their own logic-based calls for the obligation to reduce suffering impartially. In this paper, I will describe Hare’s metaethics, show how this has served as Singer’s own metaethics for most of his academic career, and then I will describe a problem for Hare’s system that is particularly relevant to effective altruists who have been influenced by Singer’s early writings and may be repeating the mistakes that Hare bequeathed to Singer.