I want to make some broadly methodological remarks on a variety of issues. To begin with I'll talk of rules, and dwell a while on the distinction between fitting and guiding.
Imagine two systems of English grammar: one an old-fashioned system that draws heavily on the Latin grammarians, and the other a streamlined formulation due to Jespersen. Imagine that the two systems are extensionally equivalent, in this sense: they determine, recursively, the same infinite set of well-formed English sentences. In Denmark the boys in one school learn English by the one system, and those in another school learn it by the other. In the end the boys all sound alike. Both systems of rules fit the behavior of all the boys, but each system guides the behavior of only half the boys. Both systemsfit the behavior also of all us native speakers of English; this is what makes both systems correct. But neither system guides us native speakers of English; no rules do, except for some intrusions of inessential schoolwork.
My distinction between fitting and guiding is, you see, the obvious and fiat-footed one. Fitting is a matter of true description; guiding is a matter of cause and effect. Behavior fits a rule whenever it conforms to it; whenever the rule truly describes the behavior. But the behavior is not guided by the rule unless the behaver knows the rule and can state it. This behaver observes the rule.
But now it seems that Chomsky and his followers recognize an intermediate condition, between mere fitting and full guidance in my flatfooted sense of the word. They regard English speech as in some sense rule-guided not only in the case of the Danish schoolboys, but also in our own case, however unprepared we be to state the rules. According to this doctrine, two extensionally equivalent systems of grammatical rules need not be equally correct. The right rules are the rules that the native speakers themselves have somehow implicitly in mind. It is the grammarian's task to find the right rules, in this sense. This added task is set by demanding not just any old recursive demarcation of the right totality of well-formed