After the German historian Rolf Peter Sieferle took his own life last September at age 67, Süddeutsche Zeitung, the country’s progressive paper of record, called his erudition “breathtaking.” For three decades Mr. Sieferle had applied the old traditions of German social science to new preoccupations, from ecological sustainability to social capital. He was among the pioneers of German environmental history. He wrote on Marx, German conservatism around World War I and the end of Communism. He advised Angela Merkel’s government on climate change.

But last month, a posthumous collection of Mr. Sieferle’s observations on Germany’s political culture, “Finis Germania” (the title plays on a phrase meaning “the end of Germany”), hit No. 9 on the prestigious Nonfiction Book of the Month list — and a scandal erupted. Certain passages on Germany’s way of dealing with the Holocaust horrified reviewers. Die Zeit called it a book of “brazen obscenity.” The Berliner Zeitung wrote of Mr. Sieferle’s “intellectual decline.” Süddeutsche Zeitung retracted its earlier praise. The Nonfiction Book of the Month list was suspended until further notice.

The book-buying public reacted otherwise. As critical anger rose, so did sales. Soon the book was selling 250 copies an hour, according to its publisher, and ranked No. 1 on Amazon’s German best-seller list, a position it held for almost two weeks, until the publisher ran out of copies.

What exactly had Mr. Sieferle said? Was this a betrayal of his intellectual legacy, as critics claimed? A vindication of it, as his sales suggested? Or had he simply gone off the rails at a time when public opinion was doing the same?...

Mr. Sieferle neither denies nor minimizes the Holocaust. He describes it as a “Verbrechen,” or “crime.” Nor does he traffic in any obvious kind of anti-Semitism. In a letter he wrote three weeks before his death to the blogger-novelist Michael Klonovsky, who is close to the anti-immigration Alternative for Germany party, he warned the party to keep its distance from the anti-Semites (“a delusional, irrational and ignorant ideology”) who would inevitably gravitate to it.

But Mr. Sieferle is critical of Germany’s postwar culture of Holocaust memory, which he argues has taken on the traits of a religion. The country’s sins are held to be unique and absolute, beyond either redemption or comparison. “The First Commandment,” he writes, “is ‘Thou shalt have no Holocausts before me.’ ” Hitler, in retrospect, turns out to have done a paradoxical thing: He bound Germans and Jews together in a narrative for all time. In an otherwise relativistic and disenchanted world, Mr. Sieferle writes, Germans appear in this narrative as the absolute enemies of our common humanity, as a scapegoat people. The role is hereditary. There are Germans whose grandparents were not born when the war ended, yet they, too, must take on the role....