ofspeakers, with noimplications for howthisbehaviorisactuallyimplemented. For instance, justas theplanets do not
solveinternalized differential equations in order to know where to go next, we might want to say that speakers do not
invoke internalized formation rules and constraints in order to construct and understand sentences.
Somelinguists do affectthisstance:“The rules I' mworkingout are just a for mal descriptionof languages; I don't care
what they have to do with the mind.”But this abandons the mentalist thesis that we set out to adopt in Chapter 2. It
leads us away fro mthe atte mpt to understand how people manage to be language users, and hence away fro m
potentialconnections withpsychology and neuroscience. Physicists who havedevelopedinsightfulformal descriptions
of physical behavior always go on to ask what mechanism is responsible for it: if the planets don't compute their
trajectories, thenwhatmakes thetrajectoriescomeoutthewaytheydo? Thesamequestionshould beasked ofrulesof
grammar. If they are not in the mind, then whatisin the mind, such that speakers observe these regularities?
Another difference between rules of grammar and laws of physics is that rules of grammar differ from language to
language, and onedoes notcome intotheworldautomaticallyfollowing therules of Englishor any other language. By
contrast, laws of physics are universal and timeless. They are not acquired; they justare. One can break rules of
grammar; one cannot break laws of physics.
It is sometimes suggested, especially by those of a behavioristic bent, that rules of grammar are like ingrained habits.
This iscloser toacceptable,as long as weaccepttheideaofa habitnotjustas a propensitytobehave,butas a complex
ingrained cognitive organization of perception and behavior. In particular, the“habit”of using linguistic rules plays a
rolein producingsentences, perceiving sentences, making grammaticalityjudgments, making judgments of rhyme,and
solvinganagrams. Itisfar moreabstractand distantfrom actualbehavior than, say, thehabitofgoingtobedat10 p.m.
or the habit of taking such-and-such a route to work. And unlike these latter two habits, it cannot be acquired
deliberately. As we will see in the next chapter, the acquisition of language involves a complex and subtle interaction
between the child and the environment.
The proper way to understand rules of grammar, I suggest, is to situate them in the metaphysicaldomain betweenthe
conscious mind and the physical neurons: in the functional mind introduced in the previous chapter. Recalling that
discussion, we treated linguistic structures like Fig. 1.1 as functionally characterized“data structures”in the f-mind. In
those terms, the rules of grammar for a language are a general characterization of the state-space availableto its users.