"Grammar expert" has multiple senses, including but not limited to the
following:

*Sense 1*: A grammar expert has a theoretical knowledge of the syntax of a
language. Such a person is able, among other things, to parse sentences and
has the knowledge necessary to teach a course in grammar.

*Sense 2*: A grammar expert speaks and writes a prestigious dialect in a way
that most educated speakers would consider to be largely free from
grammatical errors.

*Sense 3*: A grammar expert is someone who is able to speak and comprehend
at least one dialect of a language (whether or not prestigious) and can
produce sentences which conform to the operating syntactic principles of
that dialect without giving conscious thought to the process of doing so.

To my knowledge no one has ever claimed that every native speaker of a
language is a grammatical expert in either of the first two sentences. On
the other hand, many have claimed that every native speaker of a dialect is
a grammar expert in that dialect (sense 3). The argument for the latter goes
like this:

It is true that everyone (even the experts in senses 1 and 2) makes
occasional performance blunders when speaking. However, they otherwise speak
grammatically with little conscious effort. A speaker of a certain American
dialect might say, "I ain't got none of them big green bean plants." That
speaker would never say "big them bean green plants" or "them bean plants
green big" or any of a dozen other combinations which could be grammatical
in some other hypothetical dialect but happen not to be grammatical in
theirs. While most speakers could never articulate the principles that guide
their syntactic choices, they make those choices with nearly invariable
precision and would instantly recognize violations by others. Because all
grammars (of prestigious and non-prestigious dialects alike) are
impressively complex and sophisticated, the mastery of them that native
speakers have achieved qualifies them as grammar experts in sense 3.

One can simultaneously believe that very few people are grammar experts and
that everyone's a grammar expert--just not in the same sense.

Dick

To join or leave this LISTSERV list, please visit the list's web interface at:
     http://listserv.muohio.edu/archives/ateg.html
and select "Join or leave the list"

Visit ATEG's web site at http://ateg.org/