Ah, well the Bell Curve may be the main counterexample, and I’d actually forgotten that was even a thing. I assumed you were referring to flat earthers, Uri Geller, quack doctors, and the like. That stuff was everywhere and nobody cared.

Even though it’s still pseudoscience, I mentally have “racist pseudoscience” in its own unique category, because it feels distinct.

Regardless, I think the nature of older protests was often different. Rather than attempting to prevent the speaker from speaking, in my experience protests were most often either counterspeech or silent objection. I did some quick research that seems to bear this out. The largest protest against him, at Harvard, was a counterspeech rally. A later Harvard protest involved a silent walkout. An MIT protest involved flyering.

Now you could say that these protests were an implicit attempt to disinvite the speaker. For instance, the flyers apparently “claimed that MIT was insulting all minorities by inviting Murray to speak” [0]. But there’s no record that I can find of organized attempts to stop him from speaking. IMHO that’s the big difference versus today, and that’s what I am opposed to. Protest through counterspeech is a great thing. Silent protest also makes a great statement. Physically blocking, threatening, or attacking speakers is never ok.

[0] https://web.archive.org/web/20211203153624/http://tech.mit.e...

Anyway, if the students get violent on campus, the campus gets violent in response, and everyone loses some liberties in the process. Campus may be a “soft target” for now, but this kind of escalation is one reason that they too are becoming like prisons.