This is a gloomy period for scholars and intellectuals working within the traditions of Continental philosophy and literary theory. A few weeks ago, Evelyn Barish published an explosive book about Paul de Man — a leading practitioner and popularizer of deconstruction at Yale in the 1970s. We've known for years that de Man contributed hundreds of articles to a leading pro-Nazi newspaper during World War II. But Barish goes further, claiming that de Man was also a bigamist, a deadbeat dad, a liar, an embezzler, and a forger and falsifier of documents (some of which apparently helped to get him admitted into Harvard after he immigrated to the United States from his native Belgium in 1948).

But that's nothing compared with the latest revelations about Martin Heidegger's Nazism. Arguably the most influential European philosopher of the 20th century (only Ludwig Wittgenstein rivals him for the title), Heidegger has long been known to have been a National Socialist. He joined the Nazi Party in 1933 and remained a member through 1945. He eagerly served in an administrative post as rector of Freiburg University after Hitler assumed power. He praised the "inner truth and greatness" of National Socialism during a lecture in 1935. Never once did he express a word of moral condemnation of the Nazis or the Holocaust. (He died in 1976.)

And now, a philosophical diary Heidegger kept through World War II has just been published, displaying blatant examples of anti-Semitism. Heidegger's defenders have always noted that the philosopher flatly rejected the explicitly racial theories promoted by the Nazis, and the so-called "black notebooks" apparently corroborate that. But they also contain passages denouncing "world Jewry," the distinctively Jewish "talent for calculation," and the "collusion of 'rootless' Jews in both international capitalism and communism." These sound like quotes lifted straight out of the Protocols of the Elders of Zion.

Even before these latest revelations, Heidegger's far-right political views, as well as previously documented expressions of anti-Semitism, had inspired some to argue that his writings deserve to be removed from philosophy sections of libraries and relocated to Nazi propaganda archives. No wonder some are beating that drum even louder now, claiming that Heidegger's diary is nothing less than a "debacle" for Continental philosophy as a whole.

I'm hardly an uncritical admirer of Heidegger or his influence. Yet I've come out strongly against past efforts to excommunicate him from the philosophical canon, and nothing I've read about the black notebooks changes my view of the matter. Heidegger remains one of the greatest thinkers in the history of Western philosophy, despite his many morally and politically execrable views.

Some of Heidegger's defenders (including his student and onetime lover Hannah Arendt) have attempted to exonerate him by arguing that he was simply a naïve fool in political matters. His political pronouncements therefore deserve to be ignored in favor of his vital and lasting contributions to the revival of philosophical reflection on the meaning of Being.

This line of defense might be effective in the case of a mathematician or physicist, whose work exclusively concerns extra-human realities (numbers, equations, etc.). But Heidegger's reflections on Being always had an inextricably human dimension. In his early work — including the seminal Being and Time (1927) — Heidegger explored Being by way of a relentless examination of the only entity for whom "being" can be an issue: A human being. In his later work, he wrote obsessively about the way that science, technology, and many other 20th-century developments have led to the "oblivion of Being" in modern times. Heidegger's thought cannot be simply or easily disentangled from his distinctive interpretation of human existence and critique of modernity — both of which we now know overlapped in numerous disturbing ways with the views of various reactionaries.

That's why I prefer a different tack. In my view, Heidegger's greatness lies in his relentless, stunningly radical questioning of settled positions in the history of Western thought. Indeed, in many of the lecture courses leading up to the publication of Being and Time, in much of that book itself, and in several other courses from the late 1920s and early '30s, Heidegger treated philosophy as a way of life resolutely devoted both to posing radical questions and to resisting the urge for answers.

Heidegger's criticism of the history of Western thought is that since the time of Plato and Aristotle, philosophers have abandoned questioning in favor of proposing answers that have become dogmas that stand in the way of genuine thinking. (This is one reason why Heidegger called Socrates — who never wrote a word and spent his days antagonizing his fellow citizens with pesky questions — the "purest thinker in the West.")

Perhaps the most electrifying statement of this vision of philosophy can be found in a lecture course Heidegger taught in 1929-30:

Philosophy is the opposite of all comfort and assurance. It is turbulence, the turbulence into which man is spun, so as in this way alone to comprehend his existence without delusion. Precisely because the truth of this comprehension is something ultimate and extreme, it constantly remains in the perilous neighborhood of supreme uncertainty. No knower necessarily stands so close to the verge of error at every moment as the one who philosophizes. Whoever has not yet grasped this has never yet had any intimation of what philosophizing means.

That the man who delivered this bracing lecture would fall for the Nazis a mere four years later was not, as Arendt would have it, a sign of mere naïveté or foolishness. It was a complete betrayal of his own philosophical ideal and a flinching in the face of its strenuous demands. In place of relentless questioning and uncertainty, Heidegger bought into a comforting Teutonic fairy tale, put his faith in the most demonic false prophet in human history, and endorsed some of the vilest (and most ridiculous) conspiracy theories ever proposed.

But we can do better — in part by following Heidegger's example better than he followed it himself. Heidegger was right to insist on placing at the core of thinking the relentless questioning of every dogma — in religion, philosophy, science, economics, politics, morality, and countless other spheres of life. It would be a terrible shame if Heidegger's utter failure to live up to his own philosophical standards persuaded people to reject those standards altogether — or to reject him entirely as a guide to striving for them.