The following is an excerpt from The Name of the Rose, Umberto Eco’s debut novel from 1980. The story is set in an Italian monastery in 1327, and is an intellectually heady murder mystery doused in symbolism and linguistic ambivalence. Two characters, William of Baskerville and Adso of Melk, are conversing about using deductive reasoning to solve mysteries.
“Adso,” William said, “solving a mystery is not the same as deducing from first principles. Nor does it amount simply to collecting a number of particular data from which to infer a general law. It means, rather, facing one or two or three particular data apparently with nothing in common, and trying to imagine whether they could represent so many instances of a general law you don’t yet know, and which perhaps has never been pronounced. To be sure, if you know, as the philosopher says, that man, the horse, and the mule are all without bile and are all long-lived, you can venture the principle that animals without bile live a long time. But take the case of animals with horns. Why do they have horns? Suddenly you realize that all animals with horns are without teeth in the upper jaw. This would be a fine discovery, if you did not also realize that, alas, there are animals without teeth in the upper jaw who, however, do not have horns: the camel, to name one. And finally you realize that all animals without teeth in the upper jaw have four stomachs. Well, then, you can suppose that one who cannot chew well must need four stomachs to digest food better. But what about the horns? You then try to imagine a material cause for horns—say, the lack of teeth provides the animal with an excess of osseous matter that must emerge somewhere else. But is that sufficient explanation? No, because the camel has no upper teeth, has four stomachs, but does not have horns. And you must also imagine a final cause. The osseous matter emerges in horns only in animals without other means of defense. But the camel has a very tough hide and doesn’t need horns. So the law could be …”
“But what have horns to do with anything?” I asked impatiently. “And why are you concerned with animals having horns?”
“I have never concerned myself with them…”
When I first read this book almost seven years ago, I remember reading these lines with awe (I was reading my first books on the philosophy of science then). Like a fool on whom common sense was then lost but somehow not their meaning itself, I memorized the lines, and then promptly forgot the context in which they appeared. While randomly surfing through the web today, I found them once more, so here they are. They belong to the chapter titled “In which Alinardo seems to give valuable information, and William reveals his method of arriving at a probable truth through a series of unquestionable errors.”