The Deteriorating Intellect of the Leftists.
I'm somewhat older than the Captain, and so went to University when there were still first rate Intellectual Leftists (I actually met Galbraith once; he was so tall that Monty Python had a sketch where economists would decide whose theory was better by which one of them was tallest).
But yeah, they're not interested in listening or in debate. The only thing that I'd add is that now that the Long March through the institutions is complete, they think they've won. They don't think that they need to convince the undecided; rather, they need to intimidate the undecided to keep them from stepping out of line. I think that this explains the entirety of the hollowness of Progressive thought these days.