Essayist: Some linguists claim that competent speakers of a language have explicit knowledge of the rules of grammar for that language  However, linguistic ability is not the possession and utilization of a body of knowledge, or rules of grammar, but is more similar to a skill like riding a bicycle
Just as the typical cyclist does not need to know physics, neither does the language user need to know grammar rules
No set of rules can exhaustively describe the behavior of someone who is engaged in a complex activity.