Dear NATO protesters:

I hope you have plans to enjoy yourselves in Chicago next week, because otherwise it's hard to see why you even bother to make the trip. You are certainly not accomplishing anything for your cause, any more than the Occupy Wall Street protesters or the earlier anti-globalization protesters accomplished anything for theirs.

In fact, the recent history of mass left-wing protest is a litany of failure—a failure that people on the left seem incapable of analyzing, let alone acting upon.

Your core problem is this: Your supporters seem to think of protest as an expressive activity, a way for them to tell the world how they feel. But protest is not an expressive activity. It is a communicative activity. If you crave self-expression, join a creative-writing class. If you want to relieve your feelings, see a therapist.

The medium is the message, as the saying goes. People won't hear what you have to say if they don't like how you behave. Or don't understand it. So lose the giant papier-mâché art projects. As for pitching tents in public parks and inviting street people to move alongside you—who wouldn't expect a rapid deterioration into criminality?

Occupy Wall Street's one achievement was accomplished almost at the very beginning: its popularization of the concept of the "other 99%." That was powerful—and it was a message utterly undermined by the hobo camps that defined OWS as a movement of its own oddball 1% rather than the American mainstream. If instead OWS had staged daily 1-hour teach-ins—followed by trash pick-up in the parks where it convened—it might have proceeded to build on its first success. Instead it repelled potential followers.

The violence and confrontation that accompanied the anti-globalization protests of the late 1990s had the same results.

Organizers of left-wing protests always present themselves as helpless to contain the violent margin, the so-called Black Bloc. Maybe. But that self-presentation would carry more conviction if they announced from the start their intention to cooperate with police. "If you break the law, we'll turn you in ourselves and testify against you in court" is a message that would have powerful effect. The unwillingness to cooperate with police to prevent violence likewise sends a message about who you are, what you believe, and what your aspirations are.

Martin Luther King changed minds. The Black Panthers hardened minds. Dan Choi persuaded. ACT-UP repelled.

Yet despite this clear compare-and-contrast, the political left returns again and again to the wrong modes of protest. Maybe puppets, chants, and window-breaking are just more fun. Maybe they lack impulse control. Whatever the reason, the behavior predicts the outcome: they lose.