 In 2010, he wrote an open letter to Michigan's 52nd Attorney General Mike Cox to denounce the homophobic harassment by one of the latter's staffers, Andrew Shirvell, of a University of Michigan student, Chris Armstrong.Halperin uses the method of genealogy to study the history of homosexuality.He argues that Aristophanes' speech in Plato's "Symposium" does not indicate a "taxonomy" of heterosexuals and homosexuals comparable to modern ones.