Scott Woodcock has levied a number of objections against Aristotelian naturalism which claims that ethical norms are grounded by reason and biology. His most recent “membership objection” is a synthesis of earlier objections and consists in a trilemma. If Aristotelian naturalists answer the first horn of the trilemma by stipulating that determinations of species-membership are grounded non-empirically, and the second horn of the trilemma by stipulating rationality is species-specific, then they are confronted by a moral outsider—someone who claims that they have non-empirically determined their species membership and are thus guided by different norms of rationality than the rest of us. This permits the moral outsider to act heinously without moral sanction from Aristotelian naturalism. Critics have neglected Alasdair MacIntyre’s Aristotelian naturalism. And he has faced moral-outsider-type counterexamples before. I develop a new response to counterexamples MacIntyre’s account has faced and argue that MacIntyre’s Aristotelian naturalism is able to answer Woodcock’s membership objection. I do this by developing an empirical taxonomy-based approach that enables us to justify the moral outsider’s responsibilities while preserving the best of Aristotelian naturalism.

斯科特·伍德科克 (Scott Woodcock) 对亚里士多德的自然主义提出了许多反对意见，后者声称道德规范以理性和生物学为基础。他最近的“成员资格异议”是先前异议的综合，包含在一个三难困境中。如果亚里士多德的博物学家通过规定物种成员资格的确定以非经验为基础来回答三难困境的第一个角，而通过规定合理性是特定于物种的三难困境的第二个角是特定于物种的，那么他们面临的是一个道德局外人——某人声称他们已经非经验地确定了他们的物种成员资格，因此与我们其他人相比，他们受到不同的理性规范的指导。这允许道德局外人在没有亚里士多德自然主义的道德认可的情况下做出令人发指的行为。批评者忽视了阿拉斯代尔·麦金太尔的亚里士多德自然主义。他之前也遇到过道德局外人类型的反例。我对 MacIntyre 的帐户所面临的反例做出了新的回应，并认为 MacIntyre 的亚里士多德自然主义能够回答伍德科克的成员反对意见。为此，我开发了一种基于经验分类法的方法，使我们能够为道德局外人的责任辩护，同时保留亚里士多德自然主义的精华。