My judgment: close-mindedness is, perhaps, not a fair allegation. A better word would be parochialism.
Parochialism is a state of mind that refuses to believe that anyone thinks any differently than you (or your group).
I base my judgment on personal experience which is, perhaps unfortunately, the only real position that can be maintained in a world of "my facts are better than your facts."
I have lived four places in my life, discounting a two month stint in England: upstate New York, Washington (outside of Seattle), Utah (Provo) and Southern Maine.
Out of those four places, I consider Southern Maine to be the most parochial.
A surprising response, one would think. Utah is notoriously Red and even more notoriously Mormon. Accepted wisdom tells us that Red and Religious guarantee parochialism and, truth to tell, to a certain degree they do. But then, ah, there is my personal experience.
My personal experience begins with the fact that I believe firmly in the non-agreement of individuals. People are different. People agree on some things. They disagree on others. That's life. That's adulthood. Even at BYU we had protesters (Gulf War). And you couldn't swing a cat in the BYU humanities department without really annoying the cat as well as hitting a variant of left-leaning sympathizers (although granted, this was BYU so it was very conservative left-learning).
And it seemed to me, perhaps naively, that most people knew this fundamental fact. Diversity, multiculturalism--isn't difference of opinion what those things are all about?
But at USM, I have run across numerous people who have claimed, in tones of pure astonishment, "I don't know anyone who voted for Bush." And they've been proud of what they were saying. (In comparison, I knew one person in Utah who was surprised when Clinton won against Bush, Sr., and she was a rather sweet, unpretentious person.) Moreover, the people saying "I don’t know anyone who voted for Bush" are, supposedly, well-educated, well-read folks who consider themselves (even if I do not) rather superior to the "ordinary" voter.
To say that this tunnel vision dismays me would be an understatement. Especially when the statement "I don't know anyone who voted for Bush" is followed by a statement about Red States which makes places like South Carolina sound farther away and more foreign than, oh, say, Latvia.
To me, this degree of parochialism argues willful blindness, something that I rarely encountered en masse until I started graduate school in Southern Maine.
It is omnipresent in my courses: the assumptions of any left-leaning political doctrine are taken as unarguable. The arguments (or, usually, the supposed arguments) of the right are dismissed as crazy rhetoric. The singular bigotry of condemning Christianity wholesale is only topped by the assumption of aggrieved victimhood. Learning is about casting judgment. Forget Summers' tactlessness; you ain't going to get even that far here.
To my ears, the assumed indictments leveled at the Right sound suspiciously like those assumed indictments made in the early part of this Century by well-meaning folks (such as Ford and Lindbergh) who were convinced that a conspiracy (cartel) of wealthy Jewish businessmen was trying to run/ruin America.
The point being that the Right is often accused of being the purveyor of all that is loathsome--bigotry, prejudice, intolerance, etc. etc.--but it might do the Left well to remember that throughout History, well-meaning, well-educated, well-read people with Leftist tendencies have supported Hitler, Stalin and other personnages of tyranny and awfulness.
Personally, I believe that intolerance has nothing to do with politics. There are the big intolerances like racism or sexism which you will find in various groups, families, organizations, no matter what their stripe. There are the small intolerances, like an antipathy for country music, which vary from individual to individual. It's a mixed bag. There're precious few people in this world who aren't a regular compost heap of attitudes. But for me, the real intolerance begins when those who are intolerant perceive their intolerance not as some by-product of religious belief or familial duty or devotion to class/race/etc. but simply as the way things are.
Frankly, Higher Education has a long way to go.