Onora O'Neill (1987, 41, 42) writes that idealization “can easily lead to falsehood.” She points out that idealizations, particularly idealizations of persons, are especially problematic in the arena of practical reasoning. The difficulty is that “if the world is to be adapted to fit the conclusions of practical reasoning, and these assume certain idealizations, the world rather than the reasoning may be judged at fault. More concretely, agents and institutions who fail to measure up to supposed ideals may be blamed for the misfit.” In this chapter I suggest that, at times, the omissions and problematic conclusions that result from idealizations are truly moral lapses in the practice of ethics itself. The theories under consideration are typical of a brand of philosophical bioethics that depends heavily on idealizations and hypothetical examples. In the name of simplification, hypotheticals and hyperboles, employing empirically inadequate descriptions drawn from stereotypes, are used to explore and illuminate intuitions. The effects of the idealizing assumptions on the outcomes, however, are rarely examined.