It is a good theme, and it has attracted the attention of other writers too — the British journalist Nick Cohen, for example, examined it in his estimable 2007 book “What’s Left? How the Left Lost Its Way.” Indeed, so fertile is this idea, so appealing is it as an object of inquiry, we may even speak of a distinct category of recent books devoted to elaborations of it. Richard Wolin’s “Seduction of Unreason,” on the intellectual romance with fascism, is a distinguished instance, written from the left. Paul Hollander’s “End of Commitment,” on intellectuals, revolutionaries and political morality, is another, this time from the right. The many books written in the last 20 years about the German philosopher Martin Heidegger ’s complicity with Nazism represent further instances of the genre. The masterwork, however, is still Julien Benda’s “Treason of the Intellectuals.” This book, written in 1927 by one of the leading French intellectuals of the early 20th century, may be regarded as ...