German philosopher Martin Heidegger, widely considered one of the most influential philosophers of the 20th century, was a Nazi, a fact known to most anyone with more than a passing knowledge of the subject. In a New York Review of Books essay, Harvard intellectual historian Peter E. Gordon points out that “the philosopher’s complicity with the Nazis first became a topic of controversy in the pages of Les Temps modernes shortly after the war.” The issue arose again when a former student of Heidegger published “a vigorous denunciation” in 1987. In these cases, and others—like his protégé and onetime lover Hannah Arendt’s defense of her former teacher—the scandal tends to “always end with the same unsurprising discovery that Heidegger was a Nazi.”

What stirs up controversy isn’t Heidegger’s membership in the party, but his motivations. Was he simply a shrewd, if craven, careerist, or a genuinely hateful anti-Semite, or a little from each column? Whatever the explanation, Heideggerians have been able to wall off the philosophy from supposed moral or political lapses in judgment. Arendt did so by claiming that Heidegger, and all of philosophy, was politically naïve. Recalls Adam Kirsch in the Times:

The seal was set on his absolution by Hannah Arendt, in a birthday address broadcast on West German radio. Heideg­ger’s Nazism, she explained, was an “escapade,” a mistake, which happened only because the thinker naïvely “succumbed to the temptation . . . to ‘intervene’ in the world of human affairs.” The moral to be drawn from the Heidegger case was that “the thinking ‘I’ is entirely different from the self of consciousness,” so that Heideg­ger’s thought cannot be contaminated by the actions of the mere man.