People like Mr Perry find it inconceivable that people who don't agree with them can have honest and principled reasons for not agreeing with them. They find it impossible to imagine anyone thinking differently than they, so anyone who does must either be a villain, or a fool.

This isn't necessarily because they are mean or cruel people, or even stupid, but because they cannot imagine any train of thought that is not parallel with theirs. Its a form of empathy deficit, and it makes them incapable of understanding others.

This character (or perhaps it is cultural) flaw leads them to associate only with others just like them, which further reinforces their belief that they have a lock on the real truth and that those who do not accept their version of reality are either dangerous or insane. I suppose from their point of view, we are.

Unfortunately, when you are convinced your opponents must be either dangerous or insane, villains or fools, and they insist on attempting to obstruct your actions and question your motives, then anything you can do to sweep them out of your way becomes justified. In fact, it becomes imperative. A "multilateral debate" is not a good thing, a way to build consensus and unity; it is a strategy of the devil, meant to obscure the obvious and confound the righteous.

There seems to be a lot of that going around lately.