Inferring and Explaining

145 activities solely in virtue of your knowledge of facts about those activities. 5 Socrates clearly articulated this epistemological principle 2,500 years ago—“and that which we know we must surely be able to tell.” 6 I side, however, with Michael Polanyi when he says, “We can know more than we can tell.” 7 He uses a very apt example: Tis fact seems obvious enough; but it is not easy to say exactly what it means. Take an example. We know a person’s face, and can recognize it among a thou- sand, indeed among a million. Yet we usually cannot tell how we recognize a face we know. So most of this knowledge cannot be put into words. 8 Polanyi introduces the technical term tacit knowledge to label knowledge or skills that “can- not be put into words.” Polanyi is surely engag- ing in purposeful hyperbole. Most skills can be put into words, but these words are usually vague and general, and at times, the words are downright misleading. Te essence of Glass’s frst problem—“how one explanation should be compared against another so that the best explanation can be identifed”—is that most of the defenders and critics of inference to the best explanation seem to seek something that I believe is unattainable. Tey seem to be searching for a kind of mechani- cal algorithm that validates an objective deter- mination of one explanation being superior to another explanation. Perhaps the biggest temp- tation for insisting on a list of necessary and suf- fcient conditions for being the best explanation or story (or a better explanation or story) is the persistent illusion that all things we are skilled at can be articulated in clear, concise recipes or formulae. Tis is precisely the Plato and Stanley article of faith—“that which we know we must surely be able to tell.” We should know that is a mistake. Consider how remarkable it is that major league hitters can hit ninety-fve-mile-an-hour fastballs. A typical major league fastball travels about 10 feet in just the 75 milliseconds that it takes for sensory cells in the retina to confrm that a baseball is in view and for information about the fight path and veloc- ity of the ball to be relayed to the brain. Te entire fight of the baseball from the pitcher’s hand to the plate takes just 400milliseconds. And because it takes half that time merely to initiate muscular action, a major league batter has to knowwhere he is swinging shortly afer the ball leaves the pitcher’s hand—well before it’s even halfway to the plate. . . . A batter could just as well close his eyes once the ball is halfway to home plate. Given the speed of the pitch and the limi- tations of our physiology, it seems to be amiracle that anybody hits the ball at all. 9 So how do they do it? Tere are the clichés— “Keep your eye on the ball,” “Don’t open up too soon,” and the like. But these don’t tell you how it’s done; they aremnemonics to help skilled hit- ters get back on track when they are in slumps. No one has yet, and I insist never will, articu- late the logical criteria for hitting major league fastballs.Tis emphatically does not mean, how- ever, that the hitting, not the describing, can’t be done. Tis skill, like many others, is a kind of tacit knowledge. My mentor, Larry Wright, tells an important story: exPlanatory VIrtue and truth