The Practical and the Theoretical Our society is divided into castes based upon a supposed division between theoretical knowledge and practical skill. The college professor holds forth on television, as the plumber fumes about detached ivory tower intellectuals. The felt distinction between the college professor and the plumber is reflected in how we think about our own minds. Humans are thinkers, and humans are doers. There is a natural temptation to view these activities as requiring distinct capacities. When we reflect, we are guided by our knowledge of truths about the world. By contrast, when we act, we are guided by our knowledge of how to perform various actions. If these are distinct cognitive capacities, then knowing how to do something is not knowledge of a fact - that is, there is a distinction between practical and theoretical knowledge. The world of the college professor is supposedly so different than the world of the plumber because they are viewed as employing fundamentally different mental capacities in their daily lives. The college professor doesn't "get it," because her knowledge is purely theoretical, knowledge of truths. The plumber isn't qualified to reason about a political system or the economy because skill in complex action is not an exercise of such knowledge. The cliché of the learned professor inept in practical tasks is just as familiar as that of the dumb jock. Most of us are inclined immediately to classify activities like repairing a car, riding a bicycle, hitting a jump shot, taking care of a baby or cooking a risotto as exercises of practical knowledge. And we are inclined to classify proving a theorem in algebra, testing a hypothesis in physics and constructing an argument in philosophy as exercises of the capacity to operate with knowledge of truths. The cliché of the learned professor, as inept in practical tasks as he is skilled in theoretical reasoning, is just as much a leitmotif of popular culture as that of the dumb jock. The folk idea that skill at action is not a manifestation of intellectual knowledge is also entrenched in contemporary philosophy, though it has antecedents dating back to the ancients. According to the model suggested by this supposed dichotomy, exercises of theoretical knowledge involve active reflection, engagement with the propositions or rules of the theory in question that guides the subsequent exercise of the knowledge. Think of the chess player following an instruction she has learned for an opening move in chess. In contrast, practical knowledge is exercised automatically and without reflection. The skilled tennis player does not reflect on instructions before returning a volley - she exercises her knowledge of how to return a volley automatically. Additionally, the fact that exercises of theoretical knowledge are guided by propositions or rules seems to entail that they involve instructions that are universally applicable - the person acting on theoretical knowledge has an instruction booklet, which she reflects upon before acting. In contrast, part of the skill that constitutes skill at tennis involves reacting to situations for which no instruction manual can prepare you. The skilled tennis player is skilled in part because she knows how to adjust her game to a novel serve, behavior that does not seem consistent with following a rule book. The thought that aptitude at acquiring skills at practical activities is different from aptitude at acquiring knowledge of truths affects our most fundamental interactions with others. When our child exhibits skill at a physical activity, and and an initial lack of interest in mathematics, we might suppose that the child has aptitude for practical activities but not intellectual pursuits (and vice versa). But once one begins to bear down upon the supposed distinction between the practical and the theoretical, cracks appear. When one acquires a practical skill, one learns how to do something. But when one acquires knowledge of a scientific proposition, that too is an instance of learning. In many (though not all) of the world's languages, the same verb is used for practical as well as theoretical knowledge (for example, "know" in English, "savoir" in French). More important, when one reflects upon any exercise of knowledge, whether practical or theoretical, it appears to have the characteristics that would naïvely be ascribed to the exercise of both practical and intellectual capacities. A mathematician's proof of a theorem is the ideal example of the exercise of theoretical knowledge. Yet in order to count as skilled at math, the mathematician's training - like that of the tennis player - must render her adept in reacting to novel difficulties she may encounter in navigating mathematical reality. Nor does exercising one's knowledge of truths require active reflection. I routinely exercise my knowledge that one operates an elevator by depressing a button, without giving the slightest thought to the matter. From the other direction, stock examples of supposedly merely practical knowledge are acquired in apparently theoretical ways. People can and often do learn how to cook a risotto by reading recipes in cookbooks. Perhaps one way to distinguish practical knowledge and theoretical knowledge is by talking. When we acquire knowledge of how to do something, we may not be able to express our knowledge in words. But when we acquire knowledge of a truth, we are able to express this knowledge in words. Somebody may know how to make a baby laugh but not be able to express how they do it. But if someone knows that Washington is the capital of the United States, they are presumably able to express this knowledge in words. However, the distinction between what we are able to express in words and what we are unable to so express does not track any supposed distinction between practical and theoretical knowledge. I may know that the secret password is 415XH, but I may not be able to express this knowledge in words - I may only be able to press the keys when given a keypad (the knowledge resides, so to speak, in my fingers). One might then think that being able to express something in words is not necessary for theoretical knowledge. Conversely, one may think that anyone who knows how to do something is able to express that knowledge in words. After all, someone who knows how to make a baby laugh can, when asked how to do it, say, "This is the way to make a baby laugh," while he makes a baby laugh. I have argued here (and at length elsewhere) that once one bears down on the supposed distinction between practical knowledge and knowledge of truths, it breaks down. The plumber's or electrician's activities are a manifestation of the same kind of intelligence as the scientist's or historian's latest articles - knowledge of truths. It is true that someone might be adept at car mechanics and hopeless at philosophy. But it is also true that someone might be adept at theoretical physics and hopeless at philosophy. Distinctions between what one is adept at and what one is not adept at do not correlate with the folk distinction between practical and theoretical pursuits. If only to appropriate student loans rationally, we must also recognize distinctions between professions, the mastery of which requires learning many and perhaps more complex truths, and professions that one can master more easily. But these are distinctions along a continuum, rather than distinctions in kind, as the folk distinction between practical and theoretical pursuits is intended to be. There are barriers in our society erected by a false dichotomy between practical work and theoretical reflection. If someone develops early on a skill at repairing cars, she may falsely assume that she will not be adept at literary analysis or theorem proving. This robs not only her of opportunities but also society of a potentially important contributor to literary analysis or mathematics. The reward structure of society also assumes it, reflected in both the pay and the cost of pursuing what are thought of as the theoretical pursuits. The supposed distinction also operates on an everyday level. If one spends one's time repairing cars, one may think that one does not have the appropriate capacities to evaluate the arguments of economic "experts" on television. One might then feel alienated from such discussions and find one's sense of alienation reflected in the angry rhetoric of propagandists. The distinction between the practical and the theoretical is used to warehouse society into groups. It alienates and divides. It is fortunate, then, that it is nothing more than a fiction. Jason Stanley is professor of philosophy at Rutgers University. He is the author of three books for Oxford University Press, "Knowledge and Practical Interests," "Language in Context" and "Know How." More work can be found at his Web site.