Commies is a brilliant memoir of growing up in the culture of radicalism. But it also about the hard decisions faced by those professing a radical faith. For Radosh himself, the crisis came when he concluded in his authoritative book on Julius and Ethel Rosenberg that the couple (in whose behalf he had demonstrated as a boy) had indeed been guilty of spying. Attacked as a traitor, Radosh began to question his political commitments. His disillusionment...