Liberal commentator Jonathan Chait's headline about the most recent Democratic debate was stark: "Let's face it: The Democratic primary so far has been a debacle."

Chait and a lot of Democrats like him fear left-wing activists have forced the field to accept the latest far-left litmus tests on issues like decriminalizing illegal border crossings, health care for undocumented immigrants and forcing people to give up their private health insurance.

(Sen. Amy Klobuchar has avoided this sprint to the left, but she's polling at 1%.)

The fear is that Democrats are sabotaging their own general election prospects by embracing positions that will turn off more moderate voters in fall 2020.

But the Niskanen Center's Will Wilkinson made a contrary point last week: People don't vote on issues. They often claim they do, but the reality is they choose someone they like and then backfill the reasoning.

So how do people decide?

Here's what voters often tell me when I interview them: Their close study of issues leads them to the right candidate. And, they are independent of mind, and not at all partisan. And, they vote the person, not the party. They may even believe these things, but they're rarely true.

As the Stanford scholar of voting psychology Jon Krosnick told me once, decisionmaking occurs behind what he called "the black curtain of the unconscious." You may claim to know why you make decisions, but you're actually just guessing.

How can we guess who you will vote for?

Chris Weber, a Minnesotan who is a political scientist at the University of Arizona, told me, "By far the dominant predictor of how someone votes is party identification."

I know, I know: You're not in a party. And more and more of you are telling pollsters that you're "independent." But the fact is that you actually are in a party but you just refuse to admit it. We know this because you consistently vote for one party and not the other.

And it's understandable: The two parties are so polarized that if you lean toward one, the other is nowhere near you.

And why are you in one party and not the other? Lately it's because you really loathe the other guys. Weber reports that satisfaction with your party has stayed roughly the same in the past few decades, but "negative partisanship" has risen substantially. Which means in the "lesser of two evils" contest of every election, the greater evil has become ever more intolerable.

It's quite clannish. Seemingly atavistic, right?

But not you, right? You're really well-informed. (Heck, you read this column.)

Actually, the more engaged you are with the news, the more reliably partisan you are.

"People who are more informed are better at motivated reasoning," Weber said.

In other words, if you read a lot, you've got the cognitive chops to go out and find information to refute any argument that threatens your existing belief system.

Something to ponder.

J. Patrick Coolican 651-925-5042 Twitter: @jpcoolican patrick.coolican@startribune.com