A couple of years ago, Mitt Romney developed a bad habit. As part of his national campaign, the Republican nominee would attack President Obama over some perceived failing. Then the attack would be fact-checked and be proven wrong. Romney, confronted with proof that he was lying, would repeat the claim anyway, convinced that it didn’t matter whether he told the truth or not. It happened over and over and over again.

It underscored a dangerous development: the era of post-truth politics.

Two years later, the phenomenon hasn’t gone away. In Arkansas last week, Rep. Tom Cotton (R), his party’s U.S. Senate nominee, was caught in one of the most brazen lies of the 2014 campaign season. The right-wing congressman claimed he voted against this year’s Farm Bill because President Obama “hijacked” it, “turned it into a food-stamp bill,” and added “billions more in spending.”

As a factual matter, literally none of this is even remotely true, and fact-checkers came down hard on such shameless dishonesty – all of which might matter if Cotton gave a darn. But as Peter Urban reported yesterday, the congressman just doesn’t care about getting caught.

Rejecting criticism of its latest TV ad, Republican Senate hopeful Tom Cotton plans to keep running the “Farm Bill” message beyond its current ad buy. “We’ve gotten such great feedback from farmers, taxpayers, and supporters that we’re actually going to increase the size of the ad buy,” said David Ray, a spokesman for the Cotton campaign.

In a local interview this week, Cotton said he’s “proud” of his demonstrably dishonest commercial, adding that the fact-checkers didn’t spend time “growing up on a farm,” so he knows “a little bill more about farming than they do.”

As defenses go, Cotton’s argument is gibberish. One need not grow up on a farm to recognize the basic tenets of reality. The congressman told a lie, he knew it was a lie, he got caught telling a lie, and instead of doing the honorable thing, Cotton has decided he likes this lie.

The public discourse isn’t supposed to work this way. Under traditional American norms, politicians could be expected to spin, dodge, and slice the truth awfully thin, but there was an expectation that a candidate who got caught telling a bald-faced lie to the public was likely to end up in real trouble.

Cotton seems to believe those norms no longer apply – he can get caught lying and pay no real price at all.

In other words, Tom Cotton sees American politics in a post-truth era. He can say what he pleases, without regard for honesty, because there won’t be any meaningful consequences for deceiving the public on purpose.

Is he right? This didn’t work out too well for Romney, but Cotton’s in a much better position to prevail in Arkansas.