One of the ways fascism crept in over the years is people insisted on having "debates" with people who refused to be proven wrong (e.g., vaccines, trans rights and healthcare, climate) even though they obviously were from a scientific, factual, or moral standpoint. All in the name of "free speech" and an open marketplace of ideas. What we need to learn is to tell these people to shut the fuck up.
If someone still thinks, e.g., vaccines cause autism, they should be told they're stupid and to shut their fucking mouths for the rest of their lives.
American Nazis have gained a lot of ground by just standing there saying the same stupid, wrong shit over and over again and demanding to be proven wrong even though they won't accept any evidence to the contrary. The whole thing is done in bad faith. But our white liberal politicians and media figures are paralyzed by this kind of rhetorical attack because they want to be likable more than they want to be right either.