Oh, so is it one of Eco's characters asserting this view? That would make more sense.
It is the narrator's final despair of rationality. He and his colleagues in a publishing house, having read many conspiracy theories, start inventing their own as an intellectual game. But it gets taken up by real conspiracy theorists; hijinks ensue.
(Since there didn't seem to be one for this month, and I just ran across a nice quote.)
A monthly thread for posting any interesting rationality-related quotes you've seen recently on the Internet, or had stored in your quotesfile for ages.