That “The Protocols of the Elders of Zion,” the notorious anti-Semitic tract about a Jewish conspiracy to control the world, still has currency in parts of the world today was no deterrent for Umberto Eco. If there was anyone who could get away with a novel about the forged document’s creation, it was Eco. A towering member of Italy’s intellectual elite, he is a man as famed for his works on philosophy as he is for his best-selling novels.

But why, given the sensitivity, create a whole book around such a vicious piece of bigotry? Simple, Eco said in an interview from Italy: “I’m always fascinated by stupidity and credulity.”

He added, “If you sort through the Internet, you find [conspiracies] all the time. Not only about Jews, but that the Twin Towers were not taken down by bin Laden or al Qaeda, for instance. … Conspiracies are a way for people to say, ‘It’s not my fault. There’s someone else to blame.’”

A lapsed Catholic, Eco, 79, knew he was wading in perilous waters. Before he even published the book, he showed a manuscript to Jewish friends, and even the chief rabbi of Rome. Most gave him their approval, especially since the main character, Simone Simonini, the one who forges “The Protocols,” is so clearly repellent.

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But once the novel — titled “The Prague Cemetery” and available in an English translation in the United States this week — came out in Italy, Rome’s chief rabbi publicly questioned the book’s conclusion. In a conversation with Eco published in a national magazine, the rabbi said: “At the end the reader asks: these Jews, do they or don’t they want to overthrow society and rule the world?”

A literary scholar reviewing the book in another Italian paper was more blunt: “It can’t be denied … that the continuous description of Jewish villainy brings about a whiff of ambiguity, certainly not intended by Eco but permeating every page of the book.”

The criticism has failed to impugn Eco’s integrity. But it has put him on the defensive. His response comes down to this: He made Simonini as repugnant a villain as possible to make clear that no sensible person, not least he, could have sympathy for such a man. And anyway, a less sophisticated reader can find much worse things on the Internet, all of them free and more accessible than a $27 novel.

Perhaps to preempt criticism in America, Eco’s U.S. publisher, Houghton Mifflin Harcourt, had a back-cover blurb written by the Jewish critic Cynthia Ozick, known for her biting rebukes of anti-Semitism. And in an e-mail to The Jewish Week, Bruce Nichols, Harcourt’s senior vice president publisher, offered his own defense of Eco.

“Any reasonable reader — every reasonable reader — will understand immediately that Eco is no proponent of anti-Semitic conspiracy theories,” Nichols wrote. “The book portrays this kind of thinking as delusional and paranoid. The narrator, who ultimately crafts ‘The Protocols,’ is the most hateful narrator in literature.”

Still, Eco told The Jewish Week, “Probably, if I were a rabbi, I’d have the same concerns.” He went on, “But if there was a meter of the responses [from Jewish readers], I say, 20 to two, I had more positive responses than negative ones. A few Jewish groups even said this should be read in schools.”

The novel is set in 19th-century Europe, when revolutions are threatening, if not entirely upending, the established order. There are appearances by Garibaldi, the unifier of Italy, as well as the novelist Alexander Dumas, and Sigmund Freud. All these historical figures somehow work their way into the diary of Simone Simonini, who serves as one of the novel’s narrators.

Like the reactionary grandfather who raised him, Simonini — the only fictional character in the entire book — seeks an explanation for all the social upheaval. Given his ingrained hatred of Jews, he finds it easy to blame them for all the recent tumult.

“The fundamental feelings animating the Talmudic spirit,” we read Simonini write, as he begins to forge “The Protocols,” “are an overweening ambition to dominate the world, an insatiable lust to possess all the riches of those who are not Jewish and a grudge against Jesus Christ.”

This is not the first time that Eco has written about “The Protocols.” His second novel, “Foucalt’s Pendulum,” published in 1988, also had a chapter on the forgery, though it was just one among many other conspiracies included in the book. Eco has shown an interest in other realms of Jewish history as well — kabbalah and Jewish mysticism chief among them, which show up in many of his writings.

In part, Eco’s interest in Judaism is an outgrowth of his academic training. He wrote his dissertation, more than 50 years ago, on the theology of the medieval Christian thinker Thomas Aquinas, who is often studied in relation to Maimonides. Though he did not write his first novel, “The Name of the Rose,” until he was 48 — spending the first 25-odd years of his career as a influential postmodern philosopher — he delved back into history when he began writing fiction.

Repeatedly, he found himself drawn to “The Protocols.” He said he found it fascinating that the document continued — and continues — to be taken seriously, despite irrefutable evidence of its falsity. “Just after they were proven to be false in 1921,” he said, “people believed them more. Hitler even quoted them in ‘Mein Kampf.’ Listen,” he added, “they continue to be printed and sold in the Arab world, where they have enormous influence.”

Eco has had his own experience with anti-Semitism. He was only 10 when Mussolini, Italy’s fascist dictator, was in power. But he remembers being enthralled with the man, if for no other reason than, in a totalitarian state, there was no one to redirect him. In 1942, he even won a compulsory oratory contest for young fascists, an affiliation required of all school children.

“I elaborated with rhetorical skill on the subject, ‘Should we die for the glory of Mussolini and the immortal destiny of Italy?’” Eco recalled. “My answer was positive. I was a smart boy.” “Obviously,” he continued, “as a child in a society dominated by a dictatorship, I could not have known anything else.”

His understanding of Mussolini’s depravity would not come until years later. But he does have distinct memories of sensing, even as a youth, that something was wrong. He spoke about seeing a wealthy man scrubbing the streets in the midst of Second World War. When Eco got home, he asked his father why the man was doing such menial labor.

“Ahh,” Eco’s father said, “the Jews, they’ve been made to do work in the streets.” Explaining it now, Eco elaborated, “Jews were sent to the street to clean filth, to humiliate them.”

But it is not only the persistence of anti-Semitism that intrigues, and repulses, him. It is the very persistence of conspiracy theories themselves, whomever they defile. In “The Prague Cemetery,” Simonini explains his first contact with another conspiracy theory, one about Freemasons being behind the French Revolution. Simonini reads about it in Alexander Dumas’ novel “Joseph Balsamo,” and the passage in Eco’s novel reflects Eco’s own musings on the very nature of conspiracies.

“I wondered whether the bard” — Dumas — “had not discovered, in describing a single conspiracy, the Universal Form of every possible conspiracy,” Eco writes. “Dumas had a truly clear understanding of the human mind. What does everyone desire, and desire more fervently the more wretched and unfortunate they are? To earn money easily, to have power … and to avenge every wrong ever suffered.

“No one,” he adds, “believes their misfortunes are attributable to any shortcoming of their own; that is why they must find a culprit.”

Eco told The Jewish Week that he spent months reading up on conspiracies. And while, in “The Prague Cemetery,” their etiology is explained through Dumas’ fiction, Eco found evidence of conspiracies as far back as Homer. He learned this from Karl Popper, he said, the great 20th-century Jewish philosopher.

“Popper said conspiracies started with Homer,” Eco said. “In ‘The Iliad,’ he wrote that Troy was destroyed because, the day before, the guards who were protecting the gates were plotting to let the Greeks in.”

Despite his acute knowledge of “The Protocols,” he is aware that there are still gaps in our knowledge about the document’s origin. No one has, for instance, pinned down exactly who wrote the document — only that its contents are undeniably false. That unsolved mystery was critical for his writing of the novel, he said, for it allowed him to create the fictitious Simonini.

“That’s why I could write a book like this,” he said of the document’s unknown origins. “I could play a bit.”

Umberto Eco will be speaking about “The Prague Cemetery” at the Barnes & Noble in Union Square, 33 E. 17th St., on Tuesday, Nov. 15, at 7 p.m. Free. Call (212) 253-0810 for more information.