Foucault's Pendulum

Foucault’s Pendulum is a 1988 work of speculative fiction by Umberto Eco, an Italian philosopher. It follows a trio of employees, Jacobo Belbo, Casaubon, and Diotallevi, working at a vanity press syndication who begin to invent conspiracies for personal pleasure after growing exasperated with serious conspiracy theories about the occult. Titling their satirical project “The Plan,” the three writers grow more and more attached to their game, forgetting its satirical nature. Their project is complicated when they begin to learn that “real” conspiracy theorists are reading their publication and taking their conspiracies seriously. As a result, Jacobo Belbo is targeted by a secret society that is convinced he has the key to the hidden treasure of the Knights Templar. The book blurs the boundary between satire and reality as proponents of both sides are suddenly brought in contact with each other.

Casaubon, the narrator, hides in a technical museum in Paris after hours. He claims that a secret society has kidnapped Belbo, and has now set its sights on him. The novel backgrounds itself in this museum experience, telling most of the rest of the story in a sequence of flashbacks as Casaubon awaits his fate.

The first flashback explains how Casaubon, Belbo, and Diotallevi met and became partners. While Casaubon works on his thesis about the Knights Templar in 1970s Italy, spending time also as a political protester, he encounters Belbo, who edits at a publishing company, and his colleague Diotallevi, a spiritual Jew. The book makes an absurd claim about a hidden plan the Templars had for world domination. The author, Colonel Ardenti, also believes that the Templars guarded a radioactive Holy Grail. He postulates that the takeover will happen in 1944; clearly, the project has been put on hold.

Belbo and Casaubon secure a meeting with Ardenti, who disappears immediately after. An investigating official tells them that it is probably not a revolutionary, but rather an Occult member interested in his work. Not long after, Casaubon starts a job as a researcher. Belbo’s boss, Mr. Garamond, then hires Casaubon. Through Mr. Garamond’s publishing house, the three men make their foray into vanity publications. They learn that the business is lucrative, drawing in multitudes of terrible writers who want to publish their conspiracy theories. Garamond publishes a “serious” book through the press in order to send out a false signal of legitimacy. The trio calls the aspiring conspiracy authors “Diabolicals.”

After reading and approving hundreds of absurd works of literature, the three editors create their own theory, called “The Plan.” They borrow logical fallacies and references from the diverse pool of writers to construct an elaborate epic grounded in myth about the Knights Templar, enlisting Abulafia to cross-reference and synthesize their ridiculous claims into something that they think would be compelling to a conspiracist.

Though the plan is ridiculous, the trio of publishers gets so involved that they begin to think that the conspiracy might be real. They begin to connect Ardenti vanishing and his coded manuscript with their own machinations. Despite the rebuttal of Casaubon’s girlfriend, Lia, who thinks Ardenti’s manuscript is just a delivery checklist for a bundle of roses, the men refuse to accept her claim that their “Plan” might be a bad joke. Later, Diotallevi receives a cancer diagnosis, connecting it also to The Plan. Belbo responds to his friends’ reactions to the Plan by becoming even more obsessed than they are, hoping to drown out his personal problems.

While the three deal with their growing personal commitments to The Plan, a conspiracist, Agilé, becomes enamored by their work. Not long after, Casaubon receives a call from Belbo pleading for help. He rushes to his apartment and finds documents that leave a trail to Paris. Realizing that Agilé and his cult partners have probably abducted Belbo, he takes asylum in a closed museum where an artifact is stored that is about to be used for the conspiracists’ ritual. The conspiracists arrive and enact the ritual, summoning, to his shock, several ghostly forms, including Comte de Saint-Germain. They bring Belbo out and question him.

It is revealed that Agliè's group believes that they are the Tres society outlined in The Plan. Upset that Belbo seems to know more about The Plan than them, Agliè's team interrogates him about it. This incites a skirmish wherein Belbo is hanged from the artifact, Foucault’s Pendulum. Casaubon manages to escape via the sewer line. He makes it to a villa in the country where Belbo spent his childhood. He learns that Diotallevi has died of cancer.

At the novel’s end, Casaubon reflects on the tragedies that befell him, believing that the Tres will soon find him. He resolves not to appease them by divulging his “information” and extending the elaborate lie. With ambiguous truth value, the narrative of Foucault’s Pendulum ends on this question of whether it is morally right or wrong to furnish lies in order to create original meaning. Eco declines to deliver a statement about the truth value or eventual fate of the remaining characters, suggesting that the question may be arbitrary.