On the most basic level, the writer of the Rolling Stone article, Sabrina Rubin Erdely, was seduced by an untrustworthy source. More specifically, as the report details, she was swept up by the preconceptions that she brought to the article. As much casting director as journalist, she was looking for a single character with an emblematic story that would speak to — in her words — the “pervasive culture of sexual harassment/rape culture” on college campuses.

Journalists are often driven to cover atrocities and personal traumas by the best intentions, chiefly the desire to right wrongs and shed light on injustice — in a word, empathy. It is a noble impulse that animates a lot of important and courageous reporting. But empathy can also be a source of vulnerability for journalists, lowering their defenses against bad information.

In the case of “A Rape on Campus,” the risk of being taken in was compounded by Ms. Erdely’s approach. She was steered to “Jackie,” as she referred to the University of Virginia student in question, by a party with a vested interest: a rape survivor and sexual assault activist on campus.

It is hardly unusual for journalists to rely on members of advocacy groups for help finding characters, but it is a practice that requires extra vigilance. “You’re in a zone there where you have to be careful,” said Nicholas Lemann, a professor at Columbia and the journalism school’s former dean.

Mr. Lemann distributes a document called “The Journalistic Method” in one of his classes. It is a play on the term “the scientific method,” but in some respects, investigating a story is not so different from investigating a scientific phenomenon. “It’s all about very rigorous hypothesis testing: What is my hypothesis and how would I disprove it?” he said. “That’s what the journalist didn’t do in this case.”

Sexual assault stories are inherently tough to report. Not only are you encouraging someone to relive a traumatic experience, but you also have to amass enough corroborating detail to be confident in what is essentially an unverifiable narrative. Several years ago, when Kristen Lombardi and Kristin Jones reported a six-part series on campus rape for the Center for Public Integrity, they insisted on including only stories with a paper trail.

Rolling Stone, by contrast, chose to focus on an unreported rape case. The absence of any sort of written records or documentary evidence made it all the more critical to test the veracity of Jackie’s account in any way possible. Instead, the writer and magazine deferred to Jackie’s insistence that they not speak with people who might have — and would have — challenged her story.