Apologies for the long hiatus again. Cambridge terms move very swiftly!
I’m beginning to sketch out my thoughts on a paper on intellectualism and moral education in Plato’s Protagoras and Republic. One of my motivating questions is why Socrates in the latter dialogue adopts for the guards’ early training so many features of the cultural education described by Protagoras in the former. Here’s a question that came up in comparing the two accounts: Where does the notion of political virtue or the virtue of the citizen (politikē aretē) in these dialogues originate?
When Protagoras sets out to defend the thesis that virtue can be taught (indeed, he tries to show that virtue must in fact be successfully taught wherever political communities exist), he refers, as Socrates does, to political virtue. In the rest of the Protagoras, it seems as though Socrates is out to show (implicitly) that whatever the state is of well-habituated people in a decent city, it can’t be virtue; for virtue consists in a systematic knowledge of goods and ills. A bit further on after the description of the guards’ education in the Republic, we are told that their education results in a specifically political kind of courage (IV, 430c). A natural assumption in the context of the rest of the Republic is that courage without qualification is to be found only among the rulers, who possess wisdom. But even in this passage, there is some question about whether Socrates is actually attributing political courage to the auxiliaries, or whether the description “political courage” applies instead to the city, which is made courageous by the preservation of a belief by the auxiliaries (indeed, a not unimpossible translation of politikē andreia is “courage belonging to the city”). After all, we are told we must wait for a fuller account of courage itself. But if Socrates is only discussing the city’s virtues in this passage, then this seems both to disregard that we’ve already been told in Book III that the early education of the guards makes them moderate and courageous and also that in his discussion of moderation in Book IV, he seems to start from facts about moderation in an individual in order to find moderation in the city, rather than the other way around. It may also be useful to keep Phaedo 80a-c in mind, where Socrates refers to the virtues of non-philosophers as “demotic and political”, but no less a guarantor of happiness; such people are reincarnated among one of the social animals or in decent people (andres metrioi).
So that brings us back to my question: do we have any evidence in Greek thought prior or contemporary to Plato  about what “political virtue” might mean, and can we use that evidence to adjudicate among these different views about what Socrates means in the Republic by it?
 Some very quick TLG’ing turns up one use of politikē aretē in Xenophon (Lac. Pol. 10), but I can’t help but think there must be 5th c. antecessors of the concept, if not the precise collocation.