Has America lost its ability to reason?

I was sure I’d heard the high school teacher wrong. He told me the biggest problem he has with his students — many of whom end up in America’s top universities — was that they didn’t know how to read.

“Oh, they’ve cracked the alphabetic code,” he clarified. “What I’m saying is they don’t have the ability to sit still with a text and read it for comprehension. Even worse, when they come across something they disagree with, they think it isn’t true. I’m not talking about opinions; I’m talking about facts.”

What troubles the teacher is not that his students are reaching wrong conclusions. What troubles him is that they don’t grasp that they should make the effort to reason at all.

He’s right to worry. If the best and brightest have lost faith in the power of critical reasoning to illuminate the way forward, we’re in trouble.

Whether they realize it, ordinary people have become more comfortable with the idea that truth is relative and that emotion is a reliable and sufficient guide to finding it. For many of us, what’s true is whatever is pleasing and useful.

For at least a generation, this sort of thing has panicked conservative thinkers, who blame liberals for mainstreaming moral relativism and lack of respect for truth, except in the culturally Marxist sense of being a tool for social or political change. Relativism in this sense is no longer a specialty of the left. Here’s the nut of an exchange I’ve had many times over the past year with fellow conservatives:

“Barack Obama is a Muslim.”

“No, he’s not.”

“You have your opinion; I have mine.”

There is no way to argue with this, if by “argument” you mean the exercise of analyzing premises and data to reach a deliberative conclusion. This is argument as mere contradiction. You might say that approaching life this way will lead you into a world of trouble, but then again, you have your opinion, and they have theirs.

Which brings us to Sarah Palin and her best-selling new book, “Going Rogue.” Palin’s is plainly a red-hot political brand — and the purest instance of right-wing identity politics and its folly.

As an early Palin supporter, I cheered for the feisty small-town Alaskan who wasn’t part of the political and cultural elite. But when she started talking, revealing that she had no interesting thoughts about national governance, I was reminded of why a political elite matters. We don’t need leaders who are just like us. We need them to be smarter and more capable. Neither race, class, religion, geographical background nor any other demographic characteristic can make up for incompetence.

Palin has had a year to immerse herself in all the things a serious national leader must care about. On evidence of “Going Rogue,” she’s wasted her time.

Her mind isn’t geared toward resolving basic philosophical contradictions like her observation that corporations and politicians often collude against the common good, and her dogmatic belief in the sanctity of free enterprise. Well, which is it? You can’t hymn the majesties of capitalism’s “creative destruction” on one page, while proclaiming yourself a staunch defender of traditional families and institutions on another.

To be fair, no other Republicans have managed to reconcile this, either. The problem for Palin is that she doesn’t see that there’s anything to be reconciled. The problem for her ardent followers is that they see no reason to question her on anything and reject all criticism of her as made in bad faith. The problem for all of us is that this incoherence is increasingly taken for normal.

Palin’s vacuous populism is a crude example of intellectual corruption tainting public discourse. We saw a more sophisticated form recently when computer hackers revealed hidden e-mails from top climate scientists, in which they discussed secretly manipulating data and marginalizing heterodox colleagues, all to advance their global-warming views.

When scientists, who are supposed to be disinterested expert investigators of empirical data, are unmasked as cutthroat political infighters who don’t respect truth and its unbiased pursuit if it interferes with their agenda, it becomes harder to convince ordinary people to trust the judgment of elites.

They have their opinion, and you have yours.

The late critic Jane Jacobs defined culture as the worldview-defining thoughts you carry around in your head. Not long before she died, she wrote, “A culture is unsalvageable if stabilizing forces themselves become ruined and irrelevant.” Traditional belief in the effectiveness of reason, however imperfectly realized, has long been a stabilizing force in our liberal democracy.

If that faith is slipping into irrelevance, we are going to lose more than our minds. That beleaguered teacher’s incurious and indifferent students are bird brains in a cultural coal mine.