What could make a retired four-star general who has led two U.S. intelligence agencies nervous?

The current administration.

In an op-ed in the The New York Times, General Michael Hayden writes, “It is fair to say that the Trump campaign normalized lying to an unprecedented degree.”

We in the intelligence world have dealt with obstinate and argumentative presidents through the years. But we have never served a president for whom ground truth really doesn’t matter.

For many Americans, this is not a problem. Last year, I met a few of them in the back room of a Pittsburgh sports bar where my brother had arranged for several dozen Trump supporters to meet with me.

I knew many of them, indeed had grown up with several. But we could have been from different planets. They were angry. They work hard, pay taxes and struggle to raise children, but feel neglected by their government. And Donald Trump is still their guy. “He is an American.” “He is genuine.” “He doesn’t filter everything or parse every word.”

They didn’t seem very interested in facts, either. Or at least not in my facts. Political partisanship in America has become what David Brooks calls “totalistic.” Partisan identity, as he writes, fills “the void left when their other attachments wither away — religious, ethnic, communal and familial.” Beliefs are now so tied to these identities that data is not particularly useful to argue a point.

Hayden’s new book, “The Assault on Intelligence: American National Security in an Age of Lies,” reflects the idea that Americans are in danger of losing something precious — their reliance on truth. Can there be freedom without facts?