Some friends of mine put together a musical version of “The Princess Bride” in 1994. I wrote many of the songs and played piano.

A little while ago, we did a reunion concert version of the show. It was a nice weekend of reminiscing and catching up. However, I kept noticing one guy doing tech, whom I didn’t know, staring at me with a kind of wary wonder.

Near the end I found out why. Someone asked me if I had read Calvin Trillin’s latest book, and I said that I hadn’t — upon which this fellow injected, “He works for a conservative think tank — he doesn’t read Calvin Trillin.”

No smile, tart verging on hostile. It was a slightly awkward juncture, but I let it pass. We were having too good a time for me to dwell on it.

Interesting, though. This was a Blue America Berkeley crowd. This guy is likely exquisitely wary of stereotyping women and minorities, and yet he took my political leanings as license to label me as deaf to Mr. Trillin’s erudition and wit on the basis of a partisan antipathy to the work of anyone liberal. To him, I was an ideologue, foreign to reflection.

Forget that I had spent the weekend sitting at the piano, coaching people on songs I wrote, talking to everyone about this and that. What was important about me was my being identified as — gasp — a conservative.

Anyone who does what I do is used to running up against this type of guy now and then. I mention it not as a personal cri de coeur, but because of a larger tragedy: how ordinary such perceptions are among his demographic, and the failure of our higher education system to correct them. Instead of countering the unthinking polarization increasingly typical in our discourse, a college education too often leaves unchecked a confusion between dogma and enlightenment.

It’s one thing to understand that power is unequally distributed, or that lower social class does not mean lower intelligence or worth. A century ago, President Taft’s wife qualified as progressive in supporting the suffrage — but only for women (and men!) of a certain class. Her predecessor as first lady, Edith Roosevelt, had given a lesser grade of meals to “lower” servants than to “higher” ones. (I happen to have just read a biography of Nellie Taft, which I suppose has left me behind on my Trillin.)

Happily such assumptions of that era are six feet under. However, the current idea that the politics of Harper’s are the only way to be intelligent or moral is as blinkered as Social Darwinism.

No one could read Milton Friedman, Friedrich Hayek, Thomas Sowell, or Norman Podhoretz and see them as unintelligent ideologues, for example. Yet so powerful in Blue America is the equation of liberalism with legitimacy that many would consider devoting a book’s worth of attention to such thinkers as incompatible with being educated.

The word education, however, comes from the Latin “to lead out of” — such as out of superficially attractive mistakes like thinking the sun revolves around the earth. Many seem to think that education means to be led out of the temptations of conservatism into the correctness of liberalism.

This is false. To be educated is to understand that issues can be argued coherently from many angles.

As such, true education is logically incompatible with finger-down-the-throat revulsion at the notion of “conservatives.” One can feel said revulsion toward particular conservatives (or liberals), or subgroups thereof — but not toward conservatism as a whole.

One tic among those who do not get this is especially indicative: despising conservatives for “oversimplifying” by not including every single relevant fact in short op-eds. Yet these folks understand the limitations of space when the writer is a liberal. The assumption is that the liberal, having a lock on smarts and empathy, can be trusted.

Take Bob Herbert’s column Monday in the New YorkTimes on “environmental racism” in Dickson County, Tenn. What happened to the people there is awful and demands attention. But as to biases responsible for it, Mr. Herbert said nothing about a carefully reasoned book by an advocate for the poor that conclusively dismantles the idea that racism determines where toxic waste is dumped in America. I must note that its author, Christopher Foreman, is not a pink, bow-tie-wearing “operative” but a black university professor who used to work for the Brookings Institution.

Yet the number of liberal readers who will send Mr. Herbert livid letters for not mentioning “The Promise and Peril of Environmental Justice” may very well be zero. But let the conservative not dot every i and cross every t in an 800-word piece and he is a fraud.

Ideally, cringing at the notion of conservatism (or liberalism) would be the mark of not having had the opportunity to go to college. Instead, in our America this attitude toward conservatism is too often considered one of the very keystones of being educated.

“Why can’t Johnny read?” we were once taught to ask. But today, if Johnny learns how to read, in college he is taught that there is only one way to think.

Mr. McWhorter is a senior fellow at the Manhattan Institute.