After a quick review of Umberto Eco's "Foucalt's Pendulum" (reading all 577 pages in one night would have been self-inflicted torture), I came to the conclusion that Eco's story is satire, written with so many obscure references to alchemical nonsense, distorted histories, Jewish Mysticism, and conspiracy theories (some of which he invented specifically for the book) that any reasonable person should see that if one stops discriminating between whether propositions are right or wrong, it is possible to link any fact or idea with any other, which creates a dangerous tendency towards immersing one's mind in the conspiracy theorists' cesspool. It is not the facts or ideas they cite, but the web of assumptions, coincidences, guesses, and outright lies they weave that makes a conspiracy theory a piece of mental trash.
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The mere fact that science may not yet adequately explain an object, event, or experience does not mean the immediate explanation should automatically default to a conspiratorial, extraterrestrial, paranormal, or supernatural cause.