Foucault's Pendulum

The novel dramatizes Eco's theory of 'hermetic semiosis'—an interpretive mode that assumes hidden connections exist everywhere and that any text can be made to yield any meaning through sufficiently ingenious decoding. The three editors' Plan demonstrates this process in action: by feeding random occult fragments into a computer, they generate a coherent conspiracy that is entirely fabricated yet compelling. Eco's point is that meaning is not simply discovered in texts but constructed by readers, and that this construction can become pathological when it ignores context, evidence, and the limits of interpretation.

Both works diagnose the same cognitive pathology. In 'Ur-Fascism,' Eco lists 'obsession with a plot' as a core feature of fascist thinking—the belief that enemies are simultaneously too strong and too weak, and that history is controlled by secret forces. Foucault's Pendulum is a sustained literary exploration of that obsession, showing how intelligent people can be seduced by the pleasure of pattern-finding. The novel was published in 1988, seven years before the essay, but it functions as a fictional companion piece: both warn that the human hunger for hidden meaning can be weaponized by authoritarian movements.

The novel popularized the term 'hermetic semiosis' as a label for the interpretive mode Eco identified in early modern hermetic thought and its modern descendants. Eco developed the concept theoretically in The Limits of Interpretation (1990) and other works, but Foucault's Pendulum made it accessible to a wide readership. The novel also anticipated scholarly critiques of conspiracy theory as a narrative form, with later theorists citing it as an ethical and heuristic tool for understanding paranoid thinking. Its fictional 'Plan' serves as a model for how conspiracy theories generate plausibility from arbitrary connections.

The comparison is misleading. Brown's novel treats its conspiracy as essentially true—the narrative asks readers to believe in the hidden bloodline and secret history. Eco's novel treats its conspiracy as a fabrication from start to finish, a literary joke that spirals out of control. Foucault's Pendulum is a critique and satire of the genre that Brown later wrote straight. Eco's editors know their Plan is false; the horror comes from others believing it. Reviewers called Eco's novel 'the thinking person's Da Vinci Code,' a distinction that captures the fundamental difference in epistemological stance.

Many readers assume the Plan is a genuine conspiracy that the editors uncover, or that the novel's ambiguity leaves open the possibility of its truth. Eco is more precise: the Plan is a deliberate fiction constructed by the editors for amusement, using a computer program to generate connections. It is not discovered but invented. The novel's horror lies in the fact that fabricated conspiracy theories can become socially real through belief and repetition, not that they were secretly true all along. The ending leaves Casaubon's reliability uncertain, but the Plan's fictional origin is clear.

Reception has been strongly positive but with acknowledgment of its difficulty. Anthony Burgess called it 'an encyclopedic detective story, an intellectual triumph.' The Washington Post described it as 'as sensational, thrilling and packed with arcana as Raiders of the Lost Ark.' Publishers Weekly praised its 'intriguing cerebral exercise' while noting the climax 'may leave readers underwhelmed.' Reader reviews often warn that the first hundred pages are slow and dense with Templar history, but many consider the payoff worth the effort. It is widely regarded as Eco's most intellectually ambitious novel.