ABSTRACT Some beings, including children, animals and the mentally handicapped, seem to deserve moral consideration, despite the fact that they are not rational or moral agents. These so‐called marginal cases create a problem for theories that heavily stress the role of moral and/or rational agency in ethics: the latter seem unable to account for the former's moral status. This paper discusses the recent and original attempt of Loren Lomasky to solve this problem. It is argued that Lomasky's arguments are self‐defeating because they can only succeed by relying on common‐sense morality and, thus, by giving up the heavy stress on the role of rational agency in