By Paul Hockenos, Berlin

For decades, controversy has marred the legacy of Martin Heidegger, whose theories and complicity with the Nazi regime led many to brand him an anti-Semite.

Yet there was never a smoking gun in the late German philosopher’s expansive work, an explicit pejorative reference to Jews or Judaism as such. Heidegger admirers and critics battled over certain passages, concepts, and personal anecdotes. But neither side could issue unequivocal evidence to put to rest the long-running feud.

This, however, may change with the publication in March of Heidegger’s “black notebooks,” a kind of intellectual diary he kept during the 1930s and 40s. Officially the new material is under embargo until publication, but leaked excerpts, as well as statements by Peter Trawny, the collection’s editor, seem to illustrate beyond a doubt that Heidegger harbored anti-Semitic convictions during the Nazi dictatorship.

The excerpts have also triggered their own acrimonious debate. In recent interviews and commentary, the German editor has faced withering criticism from philosophers in France, where Heidegger’s philosophy has long found favor, over his interpretation of the notebooks and of the true nature of one of the 20th century’s philosophical giants.

In his will, Heidegger, who died in 1976, stated the order in which his unpublished writings were to be released. That drawn-out process is why the 1,200 pages of the 1930s and 1941 notebooks are being published only now.

The new material “is something very surprising, something we’ve never seen before,” says Mr. Trawny, director of the Martin Heidegger Institute at the University of Wuppertal. The scholar was chosen by the Heidegger family to edit the three volumes of the leather-covered black notebooks.

“In the late 1930s and early 1940s, Heidegger was very angry,” says Mr. Trawny. By then, he says, the philosopher realized that both Nazi ideology and his own philosophical mission, which was predicated on a national revolution and Germany’s dominance in Europe, were going to fail. “In this anger, he makes reference to Jews, including some passages that are extremely hostile. We knew that he had expressed anti-Semitism as private insights, but this shows anti-Semitism tied in to his philosophy,” says Mr. Trawny.

The editor says Heidegger’s references to a controlling “world Jewry” and to a collusion of “rootless” Jews in both international capitalism and communism are essentially the logic that informs the Protocols of the Elders of Zion, the infamous, early 20th-century, anti-Semitic forgery that claims to show a Jewish conspiracy for global domination. “He doesn’t say he’s read The Protocols,” says Mr. Trawny, “but that’s not necessary to share a certain kind of anti-Semitism with the Protocols. Nazi propaganda was full of exactly this kind of anti-Semitism.”

According to the editor, some of the material became public when he sent several sections of his own forthcoming book on the wartime notebooks to a French colleague. The passages found their way to others in France, and fuming responses to the notebooks—and to Mr. Trawny’s interpretation of them—started appearing in the French news media and on blogs late last year. Mr. Trawny says one Heidegger supporter even lobbied the Heidegger family to have him removed as editor.

French Heidegger loyalists, like the Heidegger translator François Fédier, say Mr. Trawny erred egregiously by linking Heidegger’s thoughts about Jews to Nazi ideology. Heidegger’s remarks, Mr. Fédier told Le Nouvel Observateur, taken out of context, can indeed seem odious. But, understood in the context of Heidegger’s philosophical system as a whole, these notes have nothing to do with anti-Semitism. Mr. Fédier did not respond to a request for an interview.

Another critic of Mr. Trawny, the novelist Stéphane Zagdanski, wrote a long blog post that called the new interpretations “delirious.” “Should we really accept Trawny’s conclusions that Heidegger’s theory of Being is contaminated by anti-Semitism?” he asked.

To be sure, Heidegger’s critics had already assembled a significant trove of evidence against him. For one, Heidegger was elected rector of the University of Freiburg in early 1933, just a few months after Adolf Hitler came to power. Hei­degger joined the Nazi party shortly after that and remained a member until the end of the war, even though he stepped down from the rectorship in early 1934. As late as 1949, he talked about the “fabrication of corpses in gas chambers and death camps.”

Overlap With Fascism

While he was rector, Heidegger’s record was ambivalent but not unblemished: He halted students from displaying anti-Semitic posters at the campus entrance but expressed his sympathy for Nazi student groups and undertook authoritarian reforms of the university’s structures. After the war, he was banned from teaching in Germany until 1951.

Moreover, many of Heidegger’s key concepts appear to overlap with those of fascism—though experts have never, until perhaps now, seen them linked explicitly to Jews. For example, the philosopher is scathing in his criticism of modernity’s wayward drift, the soullessness and ahistoricity of the cosmopolitan, and the rule of technology and science. He believed that the answer to this crisis of civilization lay in the revolutionary empowerment of the ethnic nation, or Volksgemeinschaft. And not just any Volk could pull mankind off its destructive path, but rather specifically the German Volk.

“We regularly see terms in Heidegger’s work like das Volk, ‘homelessness,’ ‘uprootedness,’ and ‘worldlessness,’” says Florian Grosser, a Heidegger expert in the philosophy department of the University of St. Gallen, in Switzerland. Such terms, he notes, were the standard vocabulary of Europe’s anti-Semitic right, regularly applied to Jews. But in Heidegger’s published work, “it’s not Jews he’s talking about, but rather the fate of modern man. So, if indeed he goes further in the notebooks, Mr. Grosser says, “we’re going to have to look at exactly how he connects these concepts to Jews. It could be very problematic.”

Indeed, there has never been a consensus on the depth of Hei­degger’s commitment—political or philosophical—to the Nazi cause, or to fascism as such. Was an apolitical Black Forest professor simply led astray by Hitler for a few years? Or are racist categories at the core of his philosophical convictions? Why didn’t Heidegger in the postwar decades ever once express shock, sadness, or remorse about the murder of Europe’s Jewry?

Ironically, it was not in Germany but rather in postwar France where his work was popularized in academic circles, as well as defended against its largely German detractors. While Heidegger’s thought was viewed as implicitly political in Germany, in France intellectuals ran with a distinctly apolitical rendering of his phenomenology.

Major French thinkers like Jean-Paul Sartre, Michel Foucault, and Jacques Derrida proudly claimed Heidegger as their own—and defended the turf. In the Heidegger camp, his acolytes argued that the private life of philosophers can—and must—be separated from their theoretical ideas. Furthermore, Heidegger, they claimed, ascribed to a metaphysical rather than an ethnic, blood-based concept of Volk and nation.

“The French philosophers have a lot at stake here,” says Matthias Flatscher, a philosopher at the University of Vienna, explaining the French reaction. “Heidegger is much more central to the French schools of thought, like deconstructionism and discourse analysis, than he is to German philosophy.”

“The whole discussion is a bit absurd in light of the fact that almost no one has read [the notebooks] yet,” says Mr. Grosser, of the University of St. Gallen, who said he was looking forward to getting his hands on them. “A careful and critical rereading of Heidegger is going to be necessary. But this doesn’t mean condemning all of his thought or reducing it to a philosophically disguised version of Nazi ideology.”