Kathekon

Kathekon is the Stoic name for the fitting act: what is appropriate to a being, given its nature and its situation. Diogenes Laertius credits Zeno with the word, and Cicero rendered it officium, the title word of his treatise On Duties; George Long’s 1862 index of terms gives the same pair, “duty, officium”. A kathekon is not a command laid on from outside but an action for which a reasonable justification can be given.

Epictetus measures it by relations. Enchiridion XXX opens, in Elizabeth Carter’s 1758 wording: “Duties are universally measured by Relations.” A father implies care and submission; a bad father is still a father, an unjust brother still a brother, and the reader considers not what the other does but what is to be done. Long’s 1877 Discourses applies the same method in II, 10, on the duties of life discovered from names, and in III, 2: maintaining the relations, natural and acquired, as a son, a father, a citizen.

Marcus Aurelius treats the fitting act as a task done part by part. In VI, 26 every duty is made up of certain parts, to be observed without disturbance, as one spells out a name letter by letter. The kathekon differs from the right act of the wise person, katorthoma, which is the same act done from a settled virtue: anyone can do what is fitting, only the sage does it rightly throughout. Its material is the adiaphora; health, family and city are not goods, but choosing among them is where duty is exercised, and where prohairesis is kept conformable to nature.