Do you think it’s too late for a Christmas gift idea? Not for the one I have in mind. It’s something you can give right now to anyone you like. It’s something that’s sorely needed in policy circles and political debates; namely, civility.

Alas, what we’re seeing in the marketplace of ideas today is a disturbing growth of incivility. This breakdown isn’t a failing of either the political left or right exclusively. It spreads from one end of the spectrum to the other.

This schoolyard mentality, and the name-calling that inevitably follows, are not the exclusive domain of those who attach intemperate comments to online articles. We hear it from highly educated people who write syndicated columns, publish books, and shout on radio and television talk shows.

Further down the food chain, lesser lights join in, poisoning the atmosphere still more. The Internet is a breeding ground for this type of behavior.

Someone will post a civil comment on some political topic. Almost immediately, someone else swings the verbal hammer of incivility, and from there the conversation degrades into a food fight, with invective and insult as the main course.

This breakdown is an echo of the famous “broken windows” theory of crime, popularized years ago by criminologists James Q. Wilson and George Kelling: When a broken window in a building is left unrepaired, the rest are soon broken by vandals.

That’s what we see online and on the airwaves. Once someone lowers the tone, others take it as an invitation to join in. Debates become shouting matches.

If you watch closely, you’ll see something else happening. The people who make civil comments basically shut down. A few join in the food fight, but most just disappear. They leave because the atmosphere has turned hostile to anything approaching an actual dialogue.

This is the real danger of incivility. Our free, self-governing society requires an open exchange of ideas. That can’t happen without a certain level of mutual respect for each other’s opinions and viewpoints.

What we see today is an accelerating competition between the left and the right to see which side can inflict the most damage. Increasingly, those who take part in public debates appear to be exchanging ideas when, in fact, they are trading insults: idiot, liar, moron, traitor.

The broken-windows theory shows us the dangers when it comes to both crime and debates. There’s an important difference, though. When behavioral norms break down in a community, police can restore order. However, when civility breaks down in the marketplace of ideas, the law is powerless to set things right.

And properly so. Our right to speak freely is guaranteed by those five glorious words in the First Amendment: “Congress shall make no law … .”

Still, the need for civility has never been greater. Our nation is divided as hardly ever before between the left and the right. We are at loggerheads on profoundly important political and social questions. Civilization itself is under barbaric attack from without.

Sadly, too many of us are not rising to these challenges as a democratic people. Rather than helping to reverse this decline, the rising chorus of incivility is driving out citizens of honest intent and encouraging those who trade in jeering and mockery.

If we are to prevail as a free, self-governing people, we must first govern our tongues and our pens. Restoring civility to public discourse is not an option. It is a necessity.

Who will begin the restoration of civility? It falls to all of us to help revive this important virtue.

There’s a world of difference between attacking a person’s argument and attacking a person’s character. We need to do more to respect that difference. We need to engage in rational debate and either hold our own or lose with grace.

We must defend our convictions with all the spirit we can. We should do it, though, with all the civility we can muster, no matter what our opponents do or say.

May that be our gift to one another, this year and every year.