It is undoubtedly simplistic to suggest that a single incident can shape the way a person lives his entire life. Even the survivor of a catastrophic accident is more than the accumulated scars and physical deficits thus incurred. But watching Kenneth Bowser’s new documentary, “Phil Ochs: There But For Fortune,” it is impossible not to register a story that the great singer-songwriter’s brother Michael recalls from their childhood in small-town Ohio.

He tells the filmmaker how he and Phil “were the only two Jews in the school, so we learned what it was like to be Jewish: ‘Oh, you’re Jewish?’ Pow!” Michael laughs and adds, “We also learned how to fight.”

Judging from Bowser’s film (which Michael Ochs co-produced), Phil spent the rest of his life fighting, measuring himself against the biggest bullies he could find. As one of the best of his generation of politically aware songwriters, Ochs took on segregationists, union-breakers, warmongers and the like. He would face off against rural poverty, unsafe working conditions, the Vietnam War, the coup d’etat in Chile and any other manifestations of what his friend and fellow folksinger Judy Henske calls “the unfairnesses of life.”

Bowser tells Ochs’ story methodically, deliberately and chronologically. Thanks in no small part to Michael, who is one of the great rock ‘n’ roll archivists, he had access to a huge trove of photos, audio, film and video clips, and fortunately for his project, Ochs appears to have been a hoarder who never threw away a concert flier or a newspaper clipping.

Early in the film, Bowser throws out an interesting clue to Ochs’ career, noting the 15-year-old’s obsession with the movies and his love of such unlikely heroes as John Wayne and Gary Cooper. As a couple of the film’s interview subjects shrewdly observe, Phil was a wholehearted believer in the American myth of individual heroism, the lone guy (with gun or guitar) who rights wrongs, redresses grievances and then rides off to the next fight. This is, of course, an ideology that sits rather uncomfortably with the collective action mystique of the activist left, making Ochs something of a fish out of water. But as his brother notes at one point, “He never went with the mainstream.” Even when he was swimming against it.

But the second half of “There But For Fortune,” like the life of its subject, takes an increasingly bleak turn. Ochs, who readily admitted that his great ambition was to be like Elvis, was caught between musical stools, unwilling or unable to continue in the folkie vein, unwilling to turn to so-called folk-rock and unable to be an out-and-out rocker. Artistic burnout coupled with a family history of bipolar disorder, sped forward by alcoholic binges, caused Ochs’ life to begin to unravel. He committed suicide in 1976. He was 35.

This makes for understandably dispiriting viewing. But what makes it all the harder to watch is the gnawing sense that the film hasn’t provided viewers with enough reason to be sorry for the loss. As someone who grew up listening to Phil Ochs’ records and singing his songs and sharing many of the same causes, I have no trouble explaining to myself or my friends why Ochs mattered so deeply to my cohort. But watching this film wouldn’t enlighten someone who had never heard or seen Ochs. There is too much of his life and not enough of his work for a stranger to make a judgment as to whether the film was a journey worth making.

“Phil Ochs: There But for Fortune,” written and directed by Kenneth Bowser, opens on Jan. 5 at the IFC Center (323 Sixth Ave.). For information, call (212) 924-7771 or go to www.ifccenter.com.