This article has been updated.

What’s the difference between bearing witness and indulging in voyeurism? “Allen v. Farrow,” HBO’s new documentary about director Woody Allen and actress Mia Farrow, raises that question — or at least it ought to.

The four-part series is unlikely to change anyone’s mind about whether Allen sexually abused his adopted daughter, Dylan Farrow, or about the morality of Allen’s relationship with Farrow’s daughter, Soon-Yi Previn. (Allen and Previn, who were not interviewed for the documentary, called the allegations against Allen “categorically false.”) These controversies have been publicly litigated for 28 years, time in which norms about how to treat survivors and how to weigh genius against bad or even criminal behavior have changed substantially.

But watching the documentary feels like taking a moral stress test: At every turn, it challenges the viewer — even one who believes in the power of personal narratives to change the world — to examine whether they’re learning something enlightening or just rummaging around in someone else’s pain.

I believe, as critic Lauren Oyler has written, that “we need to restore the actual violence” to sexual assault and that unflinching depictions of the aftermath of sex crimes can awaken the conscience. Contrary to observers who condemned the portrayal of rape in “Game of Thrones” as exploitative and unnecessary, I have defended it as part of the story’s argument about the omnipresence of sexual violence. The vivid testimonies of women who were attacked by movie producer Harvey Weinstein were crucial to piercing the impunity that long protected him and other powerful offenders.

For a generation of cinephiles and activists who didn’t live through the initial media coverage of the allegation against Allen, “Allen v. Farrow” may be a galvanizing event like Lifetime’s “Surviving R. Kelly” or HBO’s Michael Jackson documentary, “Leaving Neverland.” Certainly, it’s powerful to see Dylan Farrow take center stage in her own story. Moments like her meeting with the prosecutor who declined to press charges against Allen on the grounds that a trial might retraumatize Dylan show how hard those decisions can be, and how difficult it is to predict their long-term implications.

And yet, “Allen v. Farrow” repeatedly gave me the sense that I was prying into places that were revealing but not illuminating.

Directors Kirby Dick and Amy Ziering, who have made documentaries about sexual violence in the military, on college campuses and in the movie industry, got access to two sets of material that are particularly disturbing. The first is Mia Farrow’s trove of home movies, including the video in which Dylan alleges that Allen molested her. The second is a series of 1992 phone calls between Allen and Mia Farrow that she recorded with help from her son Fletcher Previn, because she believed Allen was taping her. The filmmakers say their research proves Mia Farrow’s suspicions were correct; some of the audio in the series is drawn from Allen’s recordings, which they obtained from previously sealed court records.

The video of Dylan confiding in her mother about what she said happened with Allen has long been treated as a crucial piece of evidence; Vanity Fair’s Maureen Orth reported in 1992 that Fox Channel 5 in New York obtained the recording but did not air it.

The video, like everything else about the case, has been so extensively reported that what stands out more than the details of the allegation are Dylan’s state of partial undress and her extreme youth. Watching this tape, and other movies of Dylan with her siblings and with Allen, is more intrusion than revelation. Whether viewers believe the shirtless 7-year-old on the tape probably will depend on what they believed going into the documentary.

The calls between Farrow and Allen incite a similar queasiness. There’s little new information, just an unbearable tension and suffering.

If one is convinced Allen is a predator, hearing an exchange in which Farrow laments that Allen “brought charges against me as an unfit mother” and Allen pledges “to make them stick” is a chilling confirmation. Of course, Allen partisans might read the same conversation as proof of his determination to fight for the children he had adopted.

Maybe hearing Farrow’s voice when she tells Allen, “Dylan’s a baby. How could you have done that to her?” is a kind of evidence. Or maybe it’s an opportunity to wade deeper into someone else’s pain because that pain is theatrical and engaging.

In its later episodes, “Allen v. Farrow” seeks to preempt these objections by suggesting that any inclination to turn away is a dereliction. “It’s just easier to opt out” of grappling with the allegations against Allen, Slate’s Lili Loofbourow observes. Ronan Farrow, Allen and Farrow’s son, acknowledges that the desire not to see extended even into his own family: “I just wanted to run away from this,” he says of the period in which he cautioned his sister against coming forward again.

They’re correct in a larger sense: “I’m tired of feeling like he matters more than me,” Dylan Farrow says at one point in the documentary, and she’s right to question such a calculation. Still, not all intimate material is equally revealing. There is space between running away from a survivor’s testimony and turning agony into a consumer good.

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