Not my area of speciality. But WCK Guthrie has an very well-regarded multivolume survey of ancient philosophy and a few shorter one volume surveys. I have no idea what his politics are, if any. Martha Nussbaum is a philosopher of progressive (not Marxist) bent who has written extensively on ancient philosophy. I know several radical (anarchist and Marxist) medeivalists, but their work is rather technical and as far as I know their politics do not impinge on it much, though Peter King (a Marxist medievalist at Ohio State) has a paper somewhere, if he ever published it, on the debate on the poverty of the Church that has political overtones. There's also a collection called Marx and Aristotle that has some interesting work it. I don't know what the ancient phil scholars would think of it. Jonathan Lear, a non-MArxist progressive, as a good book on Aristotle.
jks
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