Baldwin could not have known about Ferguson and Black Lives Matter, about the presidency of Barack Obama and the recrudescence of white nationalism in its wake, but in a sense he explained it all in advance. He understood the deep, contradictory patterns of our history, and articulated, with a passion and clarity that few others have matched, the psychological dimensions of racial conflict: the suppression of black humanity under slavery and Jim Crow and the insistence on it in African-American politics and art; the dialectic of guilt and rage, forgiveness and denial that distorts relations between black and white citizens in the North as well as the South; the lengths that white people will go to wash themselves clean of their complicity in oppression.

Baldwin is a double character in Mr. Peck’s film. The elegance and gravity of his formal prose, and the gravelly authority of Mr. Jackson’s voice, stand in contrast to his quicksilver on-camera presence as a lecturer and television guest. In his skinny tie and narrow suit, an omnipresent cigarette between his fingers, he imports a touch of midcentury intellectual cool into our overheated, anti-intellectual media moment.

A former child preacher, he remained a natural, if somewhat reluctant, performer — a master of the heavy sigh, the raised eyebrow and the rhetorical flourish. At one point, on “The Dick Cavett Show,” Baldwin tangles with Paul Weiss, a Yale philosophy professor who scolds him for dwelling so much on racial issues. The initial spectacle of mediocrity condescending to genius is painful, but the subsequent triumph of self-taught brilliance over credentialed ignorance is thrilling to witness.

In that exchange, as in a speech for an audience of British university students, you are aware of Baldwin’s profound weariness. He must explain himself — and also his country — again and again, with what must have been sorely tested patience. When the students erupt in a standing ovation at the end of his remarks, Baldwin looks surprised, even flustered. You glimpse an aspect of his personality that was often evident in his writing: the vulnerable, bright, ambitious man thrust into a public role that was not always comfortable.

“I want to be an honest man and a good writer,” he wrote early in his career, in the introductory note to his first collection of essays, “Notes of a Native Son.” The disarming, intimate candor of that statement characterized much of what would follow, as would a reckoning with the difficulties of living up to such apparently straightforward aspirations. Without sliding into confessional bathos, his voice was always personal and frank, creating in the reader a feeling of complicity, of shared knowledge and knowing humor.