Michael Oakeshott (1901-1990) on Tacit Knowledge

All actual conduct, all specific activity springs up within an already existing idiom of activity. And by an 'idiom of activity' I mean a knowledge of how to behave appropriately in the circumstances. Scientific activity is the exploration of the knowledge scientists have of how to go about asking and answering scientific questions; moral activity is the exploration of the knowledge we have of how to behave well. The questions and the problems in each case spring from the knowledge we have of how to solve them, spring from the activity itself. And we come to penetrate an idiom of activity in no other way than by practising the activity; for it is only in the practice [sic] of an activity that we can acquire the knowledge of how to practise it. We begin with what we know—as scientists, with what we know of how a scientist works; as moral beings, with what we know about how to behave well—and if we knew nothing we could never begin. Gradually, and by a variety of means, we improve and extend our first knowledge of how to pursue the activity. Among such means (though in a subordinate position, because it obviously depends upon the achievement of a certain level in our knowledge of how to pursue the activity) is the analysis of the activity, the definition of the rules and principles which seem to inhere in it and in reflection upon these rules and principles. But these rules and principles are mere abridgments of the activity itself; they do not exist in advance of the activity, they cannot properly be said to govern it and they cannot provide the impetus of the activity. A complete mastery of these principles may exist alongside a complete inability to pursue the activity to which they refer. For the pursuit of the activity does not consist in the application of these principles; and even if it did, the knowledge of how to apply them (the knowledge actually involved in pursuing the activity) is not given in a knowledge of them.

(Michael Oakeshott, "Rational Conduct," in his Rationalism in Politics and Other Essays, new and expanded ed. [Indianapolis: Liberty Fund, 1991], 99-131, at 121-2 [italics in original] [essay first published in 1950])