It has become an article of liberal faith that the Republican Party has moved away from the center. If that’s true, it’s only a matter of the GOP finally catching up with Democrats’ lack of centrism.

That’s the upshot of a new Pew Research Center study about polarization in America. The country is more divided now than two decades ago, when Pew started this series. But the notion Republicans stand alone as “party of no” extremists is not borne out by the data.

Yes, the surveys show Republicans have shifted toward the right over the past 10 years. But they also show the GOP is now simply as far to the right as Democrats are to the left — and that Democrats have been moving leftward much more steadily.

Ten to 15 years ago, Pew found Democrats were much farther to the left than Republicans were to the right. Now, they’re almost equally ideological: 56 percent of Democrats surveyed this time held “mostly” or “consistently” liberal views; 53 percent of Republicans were comparably conservative.

So, why are Republicans considered more ideological than Democrats? It may be that many liberals don’t realize just how ideological they really are.

The study shows the vast majority of those who hold “consistently conservative” views are likely to call themselves “conservatives,” while only a tiny fraction of those people consider themselves moderates. But it’s different on the left. Almost a third of those who are “consistently liberal” in their beliefs think they’re moderates. Among those with “mostly liberal” views, a plurality consider themselves moderates.

Interestingly, one-third of those who actually do hold mixed views — about as many liberal beliefs as conservative ones — call themselves conservatives. It seems those self-described conservatives are closer to the middle than they realize. Only 19 percent of these centrists identify as liberals.

This is a revealing exercise, because Pew’s pollsters grade respondents’ views based on the way they answer certain questions. Then those same respondents assign themselves partisan and ideological labels.

How do we account for the greater dissonance among liberals? Maybe conservatives are more honest about how ideological they are. They might be more aware of which positions are actually conservative vs. liberal or moderate. Or they could simply be less worried about any negative connotations of their label (as opposed to calling oneself a liberal).

I don’t think this survey answers that question definitively. But I am quite sure we will not have more compromise or less polarization as long as one side of the spectrum pretends it’s immune to the disease it detects — and denounces — on the other side.

Those denunciations have a practical effect on government. When Democrats fancy themselves less extreme than Republicans, they’re less likely to accept GOP ideas in a compromise. Likewise, when Republicans are offered left-wing solutions disguised as centrism, it’s no wonder they decline.

Over time, this false drumbeat of “extremism” being a uniquely right-wing problem becomes conventional wisdom. That’s how you end up with college professors and students protesting conservative speakers as if they’re beyond the pale. It’s how you end up with the IRS being much more heavy-handed in its scrutiny of tea-party groups than left-wing groups. It’s how spending more on poorly performing public services is considered “caring,” whereas seeking a different way to deliver them is “extreme.”

It’s how you end up with the polarization and gridlock we have today.