We often hear those on the right branded as “intolerant.” We’re all a bunch of extremists who just want to shut down the other side, right? We’re unlike those on the left, who welcome debate and want to give all viewpoints a respectful hearing.

Or so we’re told. We might even start to believe it – until we encounter the oh-so-tolerant voices of our loyal opposition. Voices such as:

Josh Barro: This New York Times reporter has said of viewpoints that he calls “anti-LGBT” (lesbian-gay-bisexual-transgender): “We need to stamp them out, ruthlessly.” So he has little patience with Heritage Foundation expert Ryan Anderson, an expert on marriage issues well-known as an informed and courteous debater.

In a recent Twitter exchange with Mr. Barro, Mr. Anderson told him: “We may disagree, but [there is] no need to be uncivil,” adding, “Even in the midst of disagreement, we should treat all people with respect.” Mr. Barro disagreed: “Some policy views render people unworthy of respect.”

Lois Lerner: According to emails written by the former Internal Revenue Service official, conservatives are “crazies” and another word too obscene to quote. Conservatives who dare to criticize the government, in her view, want to “take us down.” Small wonder that the agency targeted conservative groups during Ms. Lerner’s tenure.

Lawrence Torcello: Earlier this year, the assistant professor of philosophy at the Rochester Institute of Technology recommended jail for those who disagree with his beliefs on climate change. Because “climate denial remains a serious deterrent against meaningful political action,” the government should make the “the funding of climate denial” a crime.

In a nod to free speech, Mr. Torcello distinguishes between those who deny climate change and those who fund campaigns advancing this point of view. So it seems you can disagree with him and avoid prison. Just don’t spend one thin dime promoting your point of view.

I don’t mean to suggest that the left has a monopoly on intolerance. You don’t have to flip past many TV or radio stations, or surf the Web for long before you run into the same attitude coming from some on the right. It’s just particularly rich to hear it from those on the left, who rarely stop telling us how intolerant the rest of us are.

No matter who this attitude comes from, it’s a serious problem.

There’s nothing wrong with a spirited debate, of course. Our country was founded in the wake of one of the most profound disagreements in the history of mankind. Americans tend to feel very passionately about certain subjects, and they don’t hesitate to throw a few elbows while making their views known.

There’s a world of difference, though, between thinking your opponent is wrong and thinking he’s a moron, a fool, a traitor, a racist or a crook. Or, to hear the way some people describe those on the other side, all of the above.

Why are we seeing such a rise in incivility? It’s partly rooted in human nature. We “know” certain things to be true, so those who disagree with us aren’t merely wrong; they’re stupid or evil. The idea that they’re just as intelligent and patriotic as we are, but simply see things differently, doesn’t occur to us.

It’s also the result of laziness. It takes effort to see things from someone else’s point of view. It’s far easier to assume the worst and question their motives. Besides, how else are we going to break through the din of the 24-hour news cycle and the never-ending barrage of social media without a few verbal Molotov cocktails?

We’re better than this. We need to remind ourselves that to remain a free, self-governing people, we need to temper our outbursts and restore civility to our public discourse.

It’s not a job that starts with the other guy. It starts with each one of us. The marketplace of ideas can’t flourish without respect and civility. That means more than just talking. It means listening.