I want to begin raising a series of questions about the philosophy of Cicero's De Officiis--today, what Cicero means in saying that a virtue is a source of duties (officia). That he holds this is clear; also, that he takes it to be obviously true; and yet what he might mean by it is unclear.
First, that he holds it:
Quae quattuor quamquam inter se colligata atque implicata sunt, tamen ex singulis certa officiorum genera nascuntur...(I.15)But what can this mean? Suppose we say: Cicero thinks that a virtue is a kind of knowledge (scientia), and he thinks that a virtue is a source of duties in the way that knowledge can serve as a source of things. But this seems wrong, because knowledge would presumably be a source, or origin, of actions of certain sorts ('the things that a knowledgeable person does') rather than duties. It would be strange to say, for instance, that a physician's knowledge is the source of 'duties of a physician'. (Perhaps through knowledge he recognizes those duties.)
"Although these four [sc. wisdom, justice, greatness of spirit, moderation] are connected and interwoven, still it is in each one considered singly that certain definite kinds of moral duties have their origin..." (Loeb translation)
Ac de primo quidem officii fonte diximus. (I.19)
"With this we close the discussion of the first source of duty."
Intelligendum autem est, cum proposita sunt genera quattuor, e quibus honestas officiumque manaret, splendidissimum videri, quod animo magno elatoque humanasque res despiciente factum sit. (I.61)
"We must realize, however, that while we have set down four cardinal virtues from which as sources moral rectitude and moral duty emanate, that achievement is most glorious in the eyes of the world which is won with a spirit great, exalted, and superior to the vicissitudes of earthly life."
An Aristotelian might agree that virtues are sources of duties insofar as a virtue is defined in terms of an ideal. For instance: define courage in terms of its extreme manifestation (in hand-to-hand combat, feeling reasonable degrees of fear and confidence, and holding one's position nonetheless), and then say that we have a 'duty' to do anything that helps us attain to this, or carry out some approximation or analogue of this. But: (i) it would be strange to say that, when we reason in this way, the virtue is the source of the duty; also (ii) Cicero, working within a Stoic framework, does not wish to define virtues in terms of ideals of this sort.
It might make sense to say that a virtue is a source of duties, if we take a virtue to be an inclination or impulse (a rational impulse, which Cicero refers to as a ratio): an action is an officium, then, if it somehow advances that impulse. (This is what it would be to 'follow nature' in that respect.) But then: paradoxically, everyone has the virtues (because everyone, in being a human, has these rational impulses). Also, it would still be unclear why, or how, a certain kind of action constitutes 'advancing' an impulse.
I don't think it helps to say that Cicero is merely following Panaetius in this (if he is), since Cicero himself seems to think of this as evident, not something he takes on the authority of someone else. Also, it's not clear that it is helpful to appeal to Stoic ethics generally, because, again, what one wants to know is the manner of Cicero's derivation of duties from the virtues: that virtues are sources of duties is the organizing principle of De Officiis.
But what does this mean?