Although she stumbled at times, Christine Blasey Ford’s testimony before the Senate on Thursday probably marked a net benefit for her cause. But Brett Kavanaugh’s testimony boosted his own cause by leaps and bounds.

Only a small number of people will ever actually know the truth about what happened, or didn’t happen, between Ford and Kavanaugh in the early 1980s. As the hearing into Ford’s allegation of sexual assault against Kavanaugh unfolded, the limits of our ability to conclusively assess the veracity of her story were apparent.

The takeaway, then, is that there is no certain truth to actually take away. Absent conclusive evidence in either direction, the hearing allows us only to assess the witnesses’ believability.

That brings us to another opening for gray area. It’s possible that both Ford and Kavanaugh came across credibly. This is a 36-year-old allegation. Perhaps each is convinced his or her position is truthful. Perhaps one of them is simply doing a great job at lying. When all is said and done, and the vote is called, such an impasse may be entirely unavoidable.

But sufficient as Ford’s testimony may have been, Kavanaugh’s fierce sense of righteous indignation will be seared into the nation’s political memory. Ford claimed with “100 percent” certainty the incident happened; Kavanaugh categorically denied it. But Ford produced no corroborating proof, and no further evidence outside her own memory. For both their passions, the fact remains that not one person Ford said was present at the alleged party remembers it.

That leaves us with a decades-old accusation, one person who insists it happened, one who insists it didn’t, and all those alleged to be present with no memory of the gathering during which it was said to have taken place. It is hardly enough to conclude guilt. Indeed, tellingly, as the hearing wore on, Democrats on the Judiciary Committee seemed more interested in pushing for an FBI investigation than adjudicating Kavanaugh’s guilt.

Ford’s inability to produce a shred of hard evidence other than her ostensibly sincere and emotional testimony may be justified because the allegation is old and involves a traumatic memory. But that doesn’t make Kavanaugh guilty, and if it did, just about any allegation repeated under oath could sink just about any man.

There are political calculations that will complicate the moral ones for members of the Senate. And certainly we must have confidence that our nine Supreme Court justices are of the highest character, given their duty to the country. But the question for fair-minded senators now boils down to this: Does an unprovable and uncorroborated allegation that Kavanaugh did a terrible thing as a teenager— conduct that stands in contrast to what we know about his character today— disqualify him from sitting on the Supreme Court?

Given the media’s opposition to him, Republicans’ slim Senate majority, and Ford’s emotional testimony, Kavanaugh’s nomination seemed to be in great risk after his accuser left the chamber. But his defiant performance left senators with a choice about whether to set the precedent that a vigorously denied and credibly refuted claim from a nominee’s teenage life is disqualifying.