One of my favorite sounds in the world is the voice of the late comedian Bernie Mac. I often think of an early performance of his, on the nineties standup showcase “Def Comedy Jam.” The routine, slightly less than six minutes long, is songlike in structure—after each cluster of two or three jokes, Mac yells “Kick it!” and a snippet of cheesy, drum-heavy hip-hop plays. Between these punctuations, he affects poses that would fit as comfortably within a twelve-bar blues as they do on the dimly lit Def Jam stage: sexual bravado, profane delight, sly self-deprecation, dismay and gathering confusion at a rapidly changing world. “I ain’t come here for no foolishness,” he says toward the beginning of the set, his double negative signalling playfulness and threat in equal measure. “You don’t understand,” he says again and again, sometimes stretching “understand” into four or five syllables. Then, with swift, hilarious anger, like Jackie Gleason’s: “I ain’t scared of you motherfuckers.” The “r” in “scared” is barely audible, and the subsequent profanity is a fluid, tossed-off “muhfuckas.”

Bernie Mac is, in other words—and this is the source of my love—an expert speaker of Black English, which is the subject of the recent book “Talking Back, Talking Black” (Bellevue), by the linguist, writer, and Columbia professor John McWhorter. In the book, McWhorter offers an explanation, a defense, and, most heartening, a celebration of the dialect that has become, he argues, an American lingua franca.

McWhorter’s début as a public intellectual came twenty years ago, when a fracas erupted over a proposal to use Black English—then often called Ebonics—as a teaching tool in public schools in Oakland, California. The idea was roundly ridiculed. Ebonics, people said, was simply a collection of “slang and bad grammar”—not nearly enough to make a language. The TV talking head Tucker Carlson, in a typically nasty flourish, called Black English “a language where nobody knows how to conjugate the verbs,” McWhorter recalls. The pungent reaction baffled linguists, who had long appreciated—and begun to seriously study—the “languageness” of Black English and other informal speech variants, such as Jamaican Patois, Swiss German, and Haitian Creole. McWhorter, who is black, was then teaching at nearby U.C. Berkeley, and he had a long-standing scholarly interest in black speech. He became—by dint of his race and his physical proximity to the uproar—the most prominent authority on the validity of Black English as language.

Since then, McWhorter has built a career outside the academy as a quirky populist, committed to defending linguistic novelties often derided as erroneous or as harbingers of slackening standards. He sees in such innovations evidence of the only constant in language: its endless mutability, and its corresponding ability to surprise. He hosts Slate’s popular linguistics podcast, “Lexicon Valley,” and, in another recent book, “Words on the Move” (Henry Holt), writes acceptingly of such trends as “uptalk” (the tendency to end declarative sentences with the upward lilt of the voice that usually accompanies a question) and the peppering of “like” throughout the speech of younger Americans. McWhorter brooks no condescension toward the Valley Girl. “Americans,” he laments in “Talking Back, Talking Black,” “have trouble comprehending that any vernacular way of speaking is legitimate language.”

“Talking Back, Talking Black,” then, is a kind of apologia. In five short essays, McWhorter demonstrates the “legitimacy” of Black English by uncovering its complexity and sophistication, as well as the still unfolding journey that has led to its creation. He also gently chides his fellow-linguists for their inability to present convincing arguments in favor of vernacular language. They have been mistaken, he believes, in emphasizing “systematicity”—the fact that a language’s particularities are “not just random, but based on rules.” An oft-cited instance of systematicity in Black English is the lastingly useful “habitual ‘be,’ ” whereby, Carlson’s quip notwithstanding, the formulation “She be passin’ by” contains much more than an unconjugated verb. That naked “be,” McWhorter explains, “is very specific; it means that something happens on a regular basis, rather than something going on right now.” He adds, “No black person would say ‘She be passin’ by right now,’ because that isn’t what be in that sentence is supposed to mean. Rather, it would be ‘She be passin’ by every Tuesday when I’m about to leave.’ ” A mistake to untrained ears, the habitual “be” is, “of all things, grammar.”

However logical, examples like these have failed to garner respect, because to most Americans grammar does not inhere in linguistic rule-following generally but in a set of specific rules that they have been taught to obey. McWhorter offers a couple of typical directives: “Don’t say less books, say fewer books,” and “Say Billy and I went to the store, not Billy and me went to the store.” This narrow notion of grammar has amounted to a peculiar snobbery: the more obscure and seemingly complex the grammatical rule, the more we tend to assert its importance and to esteem those who have managed to master it. “People respect complexity,” McWhorter writes. His smirking and somewhat subversive accommodation to this Pharisaism is to emphasize the ways in which Black English is more complex than Standard English.

One of these ways—the truest, I should add, to my own experience of the language—is the use of the word “up” in conjunction with a location. Hip-hop fans might recognize this construction from the chorus of the rapper DMX’s hit song “Party Up (Up in Here)”: “Y’all gon’ make me lose my mind / Up in here, up in here / Y’all gon’ make me go all out / Up in here, up in here,” etc. McWhorter, playing the tone poet’s patient exegete, scours several instances of the usage, settling on the idea that in this context “up” conveys the intimacy of the setting it qualifies. The sentence “We was sittin’ up at Tony’s,” according to McWhorter, “means that Tony is a friend of yours.” This is an artful and convincing reading, and McWhorter carries it out in an impishly forensic manner, proving his thesis that, in some respects, Black English has “more going on” than Standard English. The latter lacks such a succinct “intimacy marker” as Black English’s “up,” and someone who studied Black English as a foreign language would have a hard time figuring out when, and how, to deploy it.

The passage on “up” is characteristic of McWhorter’s strengths as a writer. In the years that he has spent popularizing ideas hatched in the halls of the academy, he has honed a friendly prose style. Some of the sentences in “Talking Back” seem designed to enact its author’s loose, democratic approach to English, and to language more broadly: sentence-ending prepositions sit happily together with uses of the singular “they.” This intelligent breeziness is the source of the book’s considerable charm. It also helps McWhorter slide past the aspects of Black English that cannot be so cheerily explained.

McWhorter’s easygoing recounting of the Ebonics affair, with its emphasis on his ecumenical approach to language, elides the way in which the episode served as an opportunity to broadcast his somewhat stonier views on black American life. McWhorter opposed the Oakland proposal—a fact that he scarcely makes clear in “Talking Back, Talking Black.” He told the story more fully in “Losing the Race,” a best-selling jeremiad published in 2000, which argued that the familiar litany of black American troubles—low academic achievement, the absence of upward mobility, and so on—were due more to cultural deficiencies like anti-intellectualism and a “cult of victimology” than to institutionalized racism. The support that some black leaders expressed for the Oakland proposal was, in McWhorter’s view, evidence of their misguided sense that “the main issue” was “not evaluating an educational policy but defending black America from racist abuse.” Black English is perfectly legitimate as language, but its use in schools wouldn’t help black students, he wrote in 1997, because, among other problems, “inner city backgrounds do not prepare many children to be receptive to education in school.”

McWhorter’s stance in “Losing the Race” won him fame as a commentator on race and society, and got him classified alongside an increasingly—but, in retrospect, fleetingly—visible cadre of black conservatives, including the economist Thomas Sowell and the writer Shelby Steele, with whom he frequently agreed on such matters. McWhorter, though, was an otherwise conventional, if slightly old-fashioned, liberal Democrat; he’d arrived at sociology’s doorstep with a bouquet of Daniel Patrick Moynihan’s ideas just as they were beginning to wilt. He didn’t deny the persistence of racism—he still inveighs against mass incarceration and the drug war—but insisted on the reality of post-sixties progress, and implored his fellow black Americans to reach out and grab their country’s newly extended hand. This thinking has slipped further out of fashion in recent years, as smartphones around the country have delivered the bad old news about blacks and the police. McWhorter’s response to the radicalism of the younger generation, notably embodied by the Black Lives Matter movement, has been an exasperated resignation. He writes about race less regularly these days, and, when he does, it is often to dismiss the new mood as a kind of cult, long on shibboleths and pieties but woefully short on methods for bettering the lives of black Americans. (A 2015 article that McWhorter wrote for the Daily Beast was titled “Antiracism, Our Flawed New Religion.”)

Early in “Talking Back, Talking Black,” McWhorter brings up the legacy of racism, only to reject it as an adequate explanation for—or tool in arguing against—the derision levelled at Black English over the years. “Surely racism plays a part in how Black English is heard,” he concedes in the book’s first chapter, before claiming that “the speech of Appalachian whites is condemned to an even greater degree.” He offers this latter assertion—doubtful, by my admittedly anecdotal lights—without a hint of evidence. He is unimpressed by, and wary of, the “sociopolitically charged argument” that “to criticize a dialect is to criticize its speakers.” McWhorter fears that its chief result is to make people—white people—“clam up.” Better, with evangelistic hopes like McWhorter’s, to root around for the language’s exceptional qualities: “up” and all the rest.

The most energetic but also the most frustrating section of “Talking Back” is a short treatise on the word “nigga.” McWhorter takes the customary care in distinguishing the word from its uglier, older cousin, “nigger,” but he pushes the distinction further than most: for McWhorter, these are not simply two separate English words, let alone two pronunciations of the same word; they are, rather, words that belong to two different dialects. “Nigger is Standard English and nigga is Black English,” he writes, matter-of-factly. “Nigga means ‘You’re one of us.’ Nigger doesn’t.”

This interpretation helps to explain the odd power that “nigga” wields over blacks and whites alike when said aloud. Richard Pryor’s use of it in his standup act in the seventies was radical not simply because street lingo had made its way onto the stage: Pryor had swung open the door between alternate cultural dimensions. Blacks suddenly felt at home—“up in the comedy club,” somebody might have said—and whites relished the brief peek into a room they rarely saw. Something similar happened, and keeps on happening, with hip-hop, many of whose practitioners use the N-word as a kind of challenge to white enthusiasts. It’s become a familiar joke: when the music’s loud, and emotions are high, who dares recite, in full, the lyric that eventually alights on “nigga”?

That “nigga” is not only one of our most controversial words but also one of our funniest is revealing, and worth puzzling over. McWhorter doesn’t allow himself the pleasure. The word’s power—and therefore its coherence, its licitness as language—is impossible to understand without a glance at the history of race-rooted subjugation in America. The emergence of Black English is owed in part to straightforwardly linguistic factors: McWhorter convincingly cites the phenomenon of recently enslaved adults straining to learn a new language, plus a syncretistic importation of vocal gestures picked up along the trail of forced migration. But it also developed as a covert, often defiant response to the surveillance state of slavery. Grammatical nuance, new vocabulary, subtleties of tone—these were verbal expressions of racism’s mind-splitting crucible, what W. E. B. Du Bois called “double consciousness.” As Henry Louis Gates, Jr., has written, black vernacular is a literary development as well as a linguistic one. “The black tradition”—from ring shouts to Ralph Ellison—“is double-voiced,” Gates writes, in the introduction to his seminal study, “The Signifying Monkey,” echoing Du Bois. The humor associated with black language play—with jokers like Pryor and Bernie Mac—directly descends from this multivocal tradition, and from the trouble that made it necessary.

This polarity—between a tragic sense of the world and the ability to make of it a kind of punch line—might help to unshroud, if only slightly, an enigma at the heart of McWhorter’s book. In a chapter on what it means to “sound black,” he is able to isolate several aspects of the “blaccent,” as he calls it—a tendency, for example, to clip certain vowel sounds and luxuriate in others. But he concedes, in the end, that elements of black speech remain mysterious. All of its facets come together in a manner that can seem inexpressible, a point he illustrates with an essentially artistic analogy: once, watching a group of young black girls execute a dance routine, he noticed something off—inarticulable, but off—in the moves of the one girl who had grown up mostly around white people. Something beyond rhythm; something like style.

Whatever this quality may be, it operates as well on Sunday morning as it does on Saturday night. Consider the voice of Martin Luther King, Jr. His rich, swooping Baptist cadences, almost musical in tone, have become part of the American soundscape. His rhetoric was a breakthrough by way of synthesis. He had an unmistakably black sound, a sound that had been forged over centuries in the privacy of segregated worship, but he fitted it, often, over flawless Standard English syntax that straddled in its rhythms the Constitution and the Bible. He sometimes sounded like an Otis Redding cover of Abe Lincoln or the text of a Psalm.

Think of the concluding passages of his most famous speeches: “I Have a Dream,” “I’ve Been to the Mountaintop.” Forget the words. King’s shudders and vibratos, half-shouts and glottal stops have become a synecdoche for the ongoing struggle for American freedom. They remind us: black talk has—at high cost, to often beautiful effect—become a moral language, too. ♦