 Aristotle would say that the virtuous person will not break their promise to their daughter, but that they are capable of doing so. The Stoics reject this response. Virtue is a reliable disposition to do what one should. I am not forced to get the cake for my daughter, but if I am truly a good person, I am incapable of doing otherwise, because I cannot but want to get her the cake (Seneca On Benefits 6.21.2–3). The Stoics conceive of virtue as a kind as practical skill that allows a person to live well, and the wise person will consistently exercise this skill, so that everything they do they do well (Stobaeus Eclogues 2.66,14–67,4, LS 61G). So an “ability” to break my promise to my daughter is something I do not want to have, as it would be a defect, a form of folly, and a disability.