Cicero’s de Officiis played a massive role in the development of Western ethics, since it was considered to be a book “concerning duties.” Agamben (Opus Dei: An Archaeology of Duty) points out, however, that the book is not really a book of ethics but a “treatise on the devoir de situation . . . on what is respectable and appropriate to do according to the circumstances” (67).
Zeno first introduced the concept of kathekon, “what is opportune,” into philosophy, and that is the term that Cicero translates as officium. Stoics distinguishes this from katarthoma, actions that are done according to the good. In the summary found in Diogenes Laertius, they distinguishes between “duties which are always incumbent and those which are not. To live in accordance with virtue is always a duty, whereas dialectic by question and answer or walking-exercise and the like are not at all times incumbent.” Right actions include “to have judgment, to be wise, to act justly, to rejoice, to help others, to live prudently” but things that are neither right nor wrong include “to speak, to ask questions, to respond, to walk, to emigrate, and the like” (quoted on 68). Officium is status-specific, “the behavior we expect from a certain subject in a situation,” behavior that might be an obligation and might be merely an expected mode of behavior. Hence, it is possible to speak of the officium of the prostitute (70).
Cicero makes precisely this kind of distinction at the outset of his treatise, and thus we have the “surprising” result that “the book destined to introduce the notion of duty into Western ethics would not attend to the doctrine of good and evil but that of the eminently variable criteria that define the action of a subject ‘in a situation’” (69).