It's impossible to separate Joe Frazier from the most celebrated double-act in boxing history. All the same, in Mark Kram Jr.'s scrupulous "Smokin' Joe: The Life of Joe Frazier," the great Philly heavyweight leaps into form without the exclusive foil of his nemesis, Muhammad Ali.

Frazier, who died in 2011, “was a good man,” writes Kram, “but not a perfect man.” An often droll, if cautionary, appreciation, “Smokin’ Joe” is no hagiography — the glorious pratfalls are too much on display — and Frazier’s legacy is surely better for it.

The boxer’s earthly passage was a whopping contradiction. Kram locates the source of Frazier’s “devouring restlessness” — the booze, the women, the wheels, all of them fast — in the conduct of his roustabout father, Rubin, a one-armed bootlegger who produced 26 children. “Change me,” Joe chortled, “you’d have to go back and change my daddy.”

But Frazier, who grew up in South Carolina, held resolutely to his homespun Christian beliefs, saying his prayers almost every night. Step out of line, if you were one of his kids, and he would threaten to “send you back to Jesus.” (Nothing ever came of such admonitions.) Kram contends that, “Frazier left (Beaufort) because he sensed that by staying he would indeed come to a disagreeable end.”

After Frazier took the gold at the 1964 Olympics, he relied on assistance from the Cloverlay Group, “a consortium” of white Philadelphia businessmen that tidied up Joe’s business affairs. When the World Boxing Association organized a tourney to decide who would inherit Ali’s title — stolen from the Champ by political forces — Frazier declined to participate, a brilliant stratagem assuring he would face but one rival for the WBA crown, Jimmy Ellis, whom Frazier dispatched in four rounds at Madison Square Garden in 1970.

In Frazier’s life story, above all, there’s the disfiguring wound from Muhammad Ali’s verbal abuse. Torrentially, Ali slandered Joe as a “gorilla” and an “Uncle Tom.” Frazier fired back, labeling his hated adversary a “half-breed.” Ali was no “true brother,” said Frazier. “If we were twins in the belly of our mama, I’d reach over and strangle him.”

It’s as if their lives were hurtling through an obsidian void toward the final reckoning at the “Thrilla in Manila,” as if all the things that had happened before 1975 were mere retinal flashes: Ali’s surprise Liston victory; Joe’s defeat by the colossus, George Foreman; the volcanoes always fuming on the horizon: Bonavena, Chuvalo, Ellis, Norton, Quarry.

Manila would have been the greatest fight of all time were it a fight and not a cosmic event. (If the three Ali-Frazier contests complete a triptych, Kram recreates each panel with a summary of dazzling precision.) Ali’s hand was raised, but everyone who cares about such things knows there was no loser in the Philippines that sweltering day.

Unquestionably, Kram elevates trainer Eddie Futch, a tactical genius, to heroic stature, citing his “moral courage” before the last round in Manila. Futch had seen seven fighters die in the ring; Joe would not be number eight. When he determined Frazier had been fighting blind, his decision to concede happened in a flash. “Sit down, son,” he said, “It’s all over.” Then there was Joe, a pillar of nobility and sorrow. This was pathos, the real inexplicable thing brought forth from the caves of our psyches and nourished in the light. Recounting it today, a hush settles over the most unforgiving fan, just as it will for readers of “Smokin’ Joe.”

At once, Frazier’s stock soared across every hostile divide, although it’s unclear if he ever really understood that. Or maybe they were both losers, and Ali was right when he told Mark Kram Jr.’s father, one of the most sublime writers of his era, “We went to Manila as champions, Joe and me, and we came back as old men.”

To those who smirk at the claim that Futch saved Joe’s life, consider the fates of two professional boxers who died from ring injuries in July; their circumstances were not dissimilar to Frazier’s in Manila. Kram believes that Joe, in his last decade, suffered from Chronic Traumatic Encephalopathy, “a progressive degenerative disease found in people who have suffered recurring brain trauma.”

When does life not have a “disagreeable end”? Joe liked to party hard, blending his favorite liquors, which were pretty much all of them. The high-speed motorcycle crash that hobbled him seems inevitable. He suffered from diabetes and recurring blood pressure issues and died of liver cancer at age 67. A Destroyer of Worlds, he lived in the shadow of no man but himself.

Even without Ali, it’s an iconic American story, but America’s demand for reconciliation can be overpowering. The pressure on Ali and Frazier to unify after so much irreparable division, if tantalizing, was always too great, and it begs several questions: Why do we need them to have achieved peaceful accord? Why the longing for a Hollywood ending? And why do we burden their memory. Could it be we suspect that the deferral of our plural, democratic ideals may be ongoing, and we seek consolation at the expense of Ali and Frazier?

Yet, amazingly, Mark Kram Jr. leaves them as fallen warriors in their twilight, side by side on a couch, sparkling in their vulnerability, never disentangled, moving, even when they’re not. I haven’t come across this revelatory account of their penultimate meeting anywhere but “Smokin’ Joe,” and, until further notice, it will have to stand, gratifying as it is.

NONFICTION

by Mark Kram Jr.

Ecco/HarperCollins

384 pages, $27.99