According to Zadie Smith, in a Guardian essay by now showered with much praise for its "honesty:
. . .writers do have a different kind of knowledge than either professors or critics. Occasionally it's worth listening to. The insight of the practitioner is, for better or worse, unique. It's what you find in the criticism of Virginia Woolf, of Iris Murdoch, of Roland Barthes. What unites those very different critics is the confidence with which they made the connection between personality and prose. To be clear: theirs was neither strictly biographical criticism nor prescriptively moral criticism, and nothing they wrote was reducible to the childish formulations "only good men write good books" or "one must know a man's life to understand his work". But neither did they think of a writer's personality as an irrelevance. They understood style precisely as an expression of personality, in its widest sense. A writer's personality is his manner of being in the world: his writing style is the unavoidable trace of that manner. When you understand style in these terms, you don't think of it as merely a matter of fanciful syntax, or as the flamboyant icing atop a plain literary cake, nor as the uncontrollable result of some mysterious velocity coiled within language itself. Rather, you see style as a personal necessity, as the only possible expression of a particular human consciousness. Style is a writer's way of telling the truth. Literary success or failure, by this measure, depends not only on the refinement of words on a page, but in the refinement of a consciousness, what Aristotle called the education of the emotions.
Style is "an expression of personality" It's also a mark of the writer's "manner of being in the world." It's also "a personal necessity. . .the only possible expression of a particular human consciousness." It's also "a writer's way of telling the truth." It's also "the refinement of a consciousness." And it's also the "education of the emotions."
That's an awful lot of weight to heap on words and sentences and paragraphs, especially in fiction, which, except in the hands of narcissists and pseudo-philosophers, is not a medium for the "expression" of anything, but the attempt to convince your readers that words on a page evoke a "world," and to make something aesthetically pleasing out of prose. If you can do this, then all of the rhetoric about "human consciousness" and "telling the truth" and educating emotions is just so much bombast.
It is in fact finally difficult to know exactly what any of the declarations made in the above-quoted passage are even supposed to mean. How am I to know anything about the writer's "personality" from reading his novel? Never mind that I don't care about his personality in the first place—I want to know what he can do with words. There's just no way that fiction can embody the writer's personality. Personality is itself a fiction that we use to make overgeneralizations about ourselves and other people. At best, a work of fiction might create what seems to be a personality "behind" the work, but this doesn't happen with all fiction (and Eliot was right in suggesting that good writers try to avoid it, anyway) and to equate that personality with the "real" personality of the writer is to confuse a trope with reality, since. neither of these personalities exist in the first place.
Perhaps style could be "the expression of a particular human consciousness" if the writer's "consciousness" was itself the subject being explored. That is, if the writer was writing some kind of psychological memoir rather than fiction. But I don't see how consciousness in this pretentious way of speaking about it is even at issue in the writing of fiction, and I certainly don't see how style has anything to do with getting it expressed. A good writer's style does exhibit certain continuities and characteristics over time, but is this an effect of "consciousness"? Isn't it just a function of that writer's particular way of living with language? Similarly, style as a way of "telling the truth" might be plausible if by this we mean that the writer has found the right style—the right words and sentences and paragraphs—to evoke the fictional world he/she is after. If it means "telling the truth" about the characters and events portrayed in the fiction. If it means telling the truth in some more metaphysical sense, telling the truth about The Way Things Really Are, then Zadie Smith is again indulging in grandiose posturing.
Even more grandiose is her ultimate contention that style has something to do with "the refinement of a consciousness" rather than refinement of "words on a page." "Style" in art and literature is a material characteristic, an identifiable, distinctive arrangement and rearrangement of the elements of the medium, whether that be language, paint, musical sound, etc. It is not some ineffable, mystical quality, a "personal necessity," something these people have but those do not. Literary style is the means by which accomplished writers manipulate language for aesthetic effect. You can educate your emotions all you'd like, but if you haven't created something aesthetically pleasing with your words, you haven't succeeded as a writer of fiction
The inevitable consequence of associating a writer's sentences with the writer’s “manner of being in the world” is to conflate a response to writing as a response to the writer. A failure of art becomes a moral defect. Conversely, an artistic success becomes a vindication of "character," the experience of art reduced to the degree of one's sympathy with the artist, however much a figment of the imagination that figure turns out to be. Compared to these "refinements of consciousness" the writer makes available, all discussion of the skill with which he/she organizes "words on a page" is, of course, "merely literary."