 Francis and Silvers do not claim that the moral status of human beings with the most significant cognitive impairments could rest on such trusteeship, or on the potential for it. But it is useful to consider two challenges facing their proposal, which they acknowledge. The first is the question of authorship or authenticity: It is not clear how a trustee’s reasoning could be said to “execute” all, as opposed to part, of “a subject’s own thinking.” It is not clear how the thinking can be the subject’s if it was wholly executed by a trustee (Wasserman and McMahan, 2012). The second challenge, shared by the notion of mental prostheses and Scanlon’s notion of the vicarious expression of judgment-sensitive attitudes, is the possibility of providing such support for nonhuman animals—a possibility Scanlon leaves open in the above passage. If it could be extended to animals, the potential for such representation would ground the full moral status of vast numbers of primates and other mammals. To close the floodgates, it would seem necessary to argue that this support was less feasible for intelligent animals, even domesticated ones, than it was for radically impaired human beings. Clearly, an argument would be needed that, in Francis and Silvers’ terms, it would be far more difficult to fashion a mental prosthesis for the former.