The audience that the New Yorker critic has in mind is "somebody who's like yourself, but in a completely different discipline."

Question: What do you set
out to accomplish when you write a literary essay?

Louis Menand:  I'm
trying to make the subject
interesting to other people, that's the main job of being a writer.
Because
it's a subject that I'm interested in, so that's what I really care
about, I
don't really usually push an agenda, and I don't feel that my main job
is to
persuade people of something.  My
main job is to help them think about something.

Question: Who is your
presumed audience when you write? 

Louis Menand:  For
the kind of places I've written for
and the kind of writing that I've done, the general way to think about
your
audience is to think about somebody who's like yourself, but in a
completely
different discipline.  So I
generally think of a biologist, or professor of biology. 
So if I'm writing about T. S.
Eliot,  this is probably someone
who's heard of T. S. Eliot, may have read some T. S. Eliot in college,
but
doesn't know a whole lot more about T. S. Eliot, because they're busy
doing more
important things with their brains, but they might be interested in
something
that I have to say about T. S. Eliot. 
So I have to write it in a way that appreciates that this
person's
probably very well educated, a smart person, and at the same time,
doesn't know
anything effectively about what it is I'm writing about. 
And that's really the trick of writing
for places like the New York Review of Books or the New Yorker, which
are two
of the places that I've written a lot for.

So that's really my audience.  Now,
the actual audience could be very different, could be a
lot of retired high school teachers, or, you know, or graduate students
or
anybody.  It's very hard to know
who your readers are, but that's who I'm... if I have somebody in my
head, that's
probably who it is.