When I first read that television host Steve Paikin was being investigated by his employer for sexual misconduct, my immediate reaction was incredulity. The allegations struck me as ridiculous. Mr. Paikin is as straight-arrow as they come. His accuser, former Toronto mayoral candidate Sarah Thomson, alleges that he asked her to sleep with him back in 2010, during a lunch at which her executive assistant was present. This seemed improbable: Who would proposition someone with a witness present? Everyone who knows Mr. Paikin (I know him slightly) seems to have shared my response.

Mr. Paikin, widely known as one of the most upright men in journalism, is host of The Agenda, the flagship public-affairs show for TVO, Ontario's public broadcaster. It's a must-see for wonks. In the olden days, his employer would probably have dismissed these allegations out of hand. But in the #MeToo age, it had no choice. As soon as he informed management of the charges, they summoned him for a grilling. (Ms. Thomson made her accusations, without naming him, in a lengthy blog posting, then sent him an accusatory e-mail demanding that he step down.) Within hours, TVO went public with the news that it had launched an independent investigation. Unusually, it didn't suspend or fire him. It simply announced that he would be removed from stories involving sexual misconduct (which, as you may know, have sent Ontario politics into quite a tailspin).

Mr. Paikin was lucky not to be suspended, people say. Some luck. His name is in the headlines, generally on the same page as all the other #MeToo stories that now dominate the news. I imagine that most people who know him don't believe a word of it. Others will think, "These days you never know." On Tuesday, Mr. Paikin could contain himself no longer and broke his silence with a passionate outpouring on his Facebook page. "I've spent 35 years building my reputation," he wrote. "In one fell swoop, these lies have prompted outrageous headlines and connected me to a story to which I have no business being connected." He called the allegations "complete fiction."

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So what's the difference between Mr. Paikin's case and the case of Patrick Brown, the former head of Ontario's Progressive Conservatives, who was booted from his job a couple of weeks ago after other sexual misconduct allegations? Those aren't proven either. Why shouldn't we feel even worse for him? Not only did he lose his job, he lost his entire political career, including a chance to be premier of Ontario.

The answer lies in the vastly different circumstances of the two cases. The allegations against Mr. Brown were reported by a reputable news outlet, CTV, which had done enough due diligence to lend them credibility. Those closest to Mr. Brown judged that they were damaging enough to sink the party's entire election campaign if he remained. So they dumped him for the good of the party. The choice was between due process and survival, and it was no contest.

Ms. Thomson was once a fringe candidate for mayor and has been on Mr. Paikin's show. She has not named the executive assistant who was at lunch that day. The media have not been able to find anybody who worked with her who could confirm it happened, or that she ever mentioned it to them. In her blog post, she insinuated that other female guests had had to sleep with him to get on his show, and that she wasn't invited back because she turned him down. "How many women have not been invited back to his show simply because they won't sleep with them?" she asked. She has invited them to come forward in order to force him to leave TVO.

To be sure, I have no idea what happened at that lunch. Maybe everything Ms. Thomson said is true and Mr. Paikin is lying through his teeth. Maybe he made a stupid joke. What I do know is that questionable or careless or unfounded allegations deal a tremendous blow to the #MeToo movement because they undermine the real victims of sexual assault and help stoke a backlash. Women should be extremely concerned about this problem. Sad to say, some are not. Too many of us have embraced the principle #BelieveAllWomen – a formula for miscarriage of justice if there ever was one. Unfortunately there are plenty of false or exaggerated claims out there. Women (just like men) lie for all kinds of reasons, including the fact that they are unbalanced or unhinged. Remember the sensational Rolling Stone piece from 2014, detailing a brutal group rape at the University of Virginia? It caused an uproar. "[T]here is a reason that people believed and continue to believe Jackie: There are so many people – too many people – who report similar attacks," the arch-feminist Jessica Valenti wrote. But the story was entirely made up, and Rolling Stone was forced to retract it in its entirety.

Too many people think that common-sense skepticism – or even a willingness to withhold judgment until the facts are in – puts you on the side of the predators. The truth is that not all men are guilty of what they've been accused of, and others aren't that guilty of very much. The world's a messy, complicated place. And given what there is to go on, I'd bet that Mr. Paikin is the same guy I thought he was last week. I may be wrong. But I don't think so.