If you didn't know better — and a lot of GOP candidates are hoping you don't — you would swear this fall that Republicans are the party of protecting Americans from being kicked off their health insurance because of pre-existing conditions.

"Covering pre-existing conditions is personal to me," Wisconsin Gov. Scott Walker (R) tweeted on Monday. "Plus, it's the right thing to do."

"When it comes to health insurance, Donald Trump and Republicans will protect patients with pre-existing conditions," Trump told a Las Vegas rally in September. "We're going to do that. We want to do it."

"I'm taking on both parties, and fighting for those with pre-existing conditions," Rep. Dana Rohrabacher (R-Calif.) says in a new campaign ad.

This is all sort of hilarious, because until about a year ago it was the central mission of the Republican Party to repeal the Affordable Care Act, otherwise known as "ObamaCare." The act has proven incredibly unpopular at times — so much so that the GOP was able to retake Congress in 2010 — but a funny thing happened: Americans figured out what was in the law. Mandatory coverage of pre-existing conditions was part of the law and also incredibly popular. Repeal failed, and while Republicans may still hate ObamaCare, they suddenly love some of its key provisions.

The anecdote comes as no surprise to liberals. Poll after poll over the years has shown that our fellow citizens don't think much of liberals or liberalism — but they share liberal views on issues ranging from money in politics to the minimum wage to climate change. It's a hell of a branding problem for left-of-center activists.

This brings us, of course, to the matter of political correctness.

"P.C." is incredibly unpopular. This won't surprise anybody who has noticed that Donald Trump has been president for nearly two years, but the notion was reinforced last week with a new studyaccompanied by a breathless headline in The Atlantic — reporting that a whopping 80 percent of Americans believe "political correctness is a problem in our country." Bad news for liberals, right?

There's just one small problem, as The Atlantic reported. "Since the survey question did not define political correctness for respondents, we cannot be sure what, exactly, the 80 percent of Americans who regard it as a problem have in mind."

That makes the report, released by a new organization called More in Common, less than helpful as a political guide. How can you solve a problem that is barely, vaguely defined?

For the record, here's one possible definition of "political correctness": Good manners.

Here's another: Being polite.

And here's another: Refusing to punch down.

At its most basic, being politically correct means you think before you talk, that you make some small effort not to give offense to the people around you, that you do a little bit of work to consider the feelings of other people — particularly when those people come from backgrounds where dealing with discrimination and oppression is a regular feature of their lives.

These are practices that, in ordinary society, might be expected of any halfway decent adult.

You know who might agree? Many of those same Americans polled in the new study. Eighty-two percent of them, for example, believe that hate speech is a problem in America. Eighty-two percent believe that racism is at least a somewhat serious problem in America. Sixty-nine percent believe that sexism is a problem. As with ObamaCare, Americans may not like the branding that comes with being politically correct, but they seem to support the particulars.

It's a bit more complicated than that, of course. There really are small pockets of society where failure to be politically correct can carry a social penalty — mostly in corners of academia. Those corners have taken on outsized power in our national imagination. "I have liberal views but I think political correctness has gone too far, absolutely," said a 28-year-old North Carolina woman quoted in the study. "We have gotten to a point where everybody is offended by the smallest thing."

While there are those exceptions, though, most Americans appreciate a good-faith effort to be polite. More than 90 percent of political correctness is simply avoiding slurs — if you aren't sure, don't say it — and listening a little bit, so you know the terms people use to describe themselves. All you have to do is restrain yourself a little bit for the good of the people around you.

Political correctness may be unpopular, but who cares? Often, it's simply the right thing to do.