Are there key respects in which character and character defects are voluntary? Can agents with serious vices be rational agents? Jonathan Jacobs answers in the affirmative. Moral character is shaped through voluntary habits, including the ways we habituate ourselves, Jacobs believes. Just as individuals can voluntarily lead unhappy lives without making unhappiness an end, so can they degrade their ethical characters through voluntary action that does not have establishment of vice as its end. Choosing Character presents an account of ethical disability, expanding the domain of responsibility and explicating the role of character in ethical cognition.

Jacobs contends that agents become ethically disabled voluntarily when their habits impair their ability to properly appreciate ethical considerations. Such agents are rational, responsible individuals who are yet incapable of virtuous action. The view develops and modifies Aristotelian claims concerning the fixity of character. Jacobs' interpretation is developed in contrast to the overlooked work of Maimonides, who also used Aristotelian resources but argued for the possibility of character change. The notion of ethical disability has profound ramifications for ethics and for current debates about blame and punishment.