 By stipulating a category of human beings with radical cognitive disabilities, we seek to avoid difficult empirical issues about the extent to which individuals classified as having serious cognitive disabilities actually lack the psychological functions held to confer moral status. Even the most direct assessments of these functions may fail to recognize atypical, especially nonverbal, forms of cognitive functioning. And with the possible exception of extreme cases like anencephaly, there are formidable difficulties in inferring a lack of cognitive capacity from a lack of specific behavior or brain activity. As recent work on intellectually conscious states has revealed (Wannez et al. 2017, Real et al. 2015), some psychological capacities are difficult to detect neurologically or behaviorally.