Recently virtue ethicists, such as Julia Annas and Matt Stichter, in order to explain what a moral virtue is and how it is acquired, suggest modeling virtue on practical expertise. However, a challenging issue arises when considering the nature of practical expertise especially about whether expertise requires articulacy, that is, whether an expert in a skill is required to possess an ability to articulate the principles underlying the skill. With regard to this issue, Annas advocates the articulacy requirement, while Stichter (...) denies. Stichter raises two objections to Annas’s requirement: first, Annas provides no argument for the requirement; second, there exist counterexamples in which there are experts who cannot articulate what and why they did in skilled performance. In this paper I shall show that Annas did provide an argument and can respond to the counterexamples; however, her argument and response are not convincing. Instead, I construct a new argument for the articulacy requirement by which I call the argument from success-conduciveness. The main idea involved in this new argument, i.e., articulacy is success-conducive, supports further that ethical expertise requires articulacy due to the seriousness of morality. (shrink)