This gives rise to the "false consensus effect," which occurs when, because of institutional provincialism, "people think that the collective opinion of their own group matches that of the larger population."
There also is "the law of group polarization": "when like-minded people deliberate as an organized group, the general opinion shifts toward extreme versions of their common beliefs." They become tone-deaf to the way they sound to others outside their closed circle of belief.
American campuses have more insistently proclaimed their commitment to diversity as they have become more intellectually monochrome.
They do indeed cultivate diversity -- in race, skin color, ethnicity, sexual preference. In everything but thought.
Academia, Stuck To the Left