What is a critique of the essay "If Black English Isn't a Language, Then Tell Me, What Is?" by James Baldwin?

In this essay, Baldwin defines the development of language as primarily a political act through which a group of people establish a distinct identity. He also differentiates between a dialect and a language.

First, according to Baldwin, a language allows a group to define and express who they are from their own point of view, instead of having their reality expressed (and misrepresented) by another group. As Baldwin puts it:

People evolve a language in order to describe and thus control their circumstances, or in order not to be submerged by a reality that they cannot articulate. (And, if they cannot articulate it, they are submerged.) A Frenchman living in Paris speaks a subtly and crucially different language from that of the man living in Marseilles.... They each have very different realities to articulate, or control.

Further, a language differs from a dialect, which is merely a version of a language. Baldwin asserts that the black experience has been so different from the white experience that black people need more than a mere version of white language:

A people at the center of the Western world, and in the midst of so hostile a population, has not endured and transcended by means of what is patronizingly called a "dialect."

He notes that being carried to America as slaves created a situation so dangerous that black people had to develop a language that the white masters couldn't understand. A dialect is comprehensible to a speaker of the same language; a separate language, by definition, has to be learned. As Baldwin says:

There was a moment, in time, and in this place, when my brother, or my mother, or my father, or my sister, had to convey to me, for example, the danger in which I was standing from the white man standing just behind me, and to convey this with a speed, and in a language, that the white man could not possibly understand, and that, indeed, he cannot understand, until today.

Thus, says Baldwin, black people, from political necessity and the need to survive, developed a language incomprehensible to whites.

If we are to critique this essay, we might argue that while parts of black English contain nuances and meanings incomprehensible to people outside of the "in" group, it is yet a dialect because it is generally comprehensible in a commonsense way to non-black speakers of English. All dialects have in-group components but do not necessarily rise to the level of a separate language. We might also question why a "dialect" is patronizing: implicitly this would be because it is derivative and hence lesser than the dominant language, but arguably this line of thought needs more development.

While accepting Baldwin's important point that black people have had to create a separate culture to survive white oppression and white distortion of truth, we could also note that many black people react against the idea of a separate language identity, wanting to assimilate to the dominant language to gain access to power, at least in terms of public discourse. 

All the same, Baldwin's essay is a powerful articulation of the need groups have to articulate their own reality.