For 15 years, I produced a weekly PBS series called “Think Tank,” hosted by Ben Wattenberg. Our slogan was “No journalists, no politicians, no food fights,” which was enough to set the program apart from most of what passed for policy discussion on television at the time, and delivered us a small but attentive audience who supported our effort to improve the public discourse.

In all those years, we did have a number of journalists on the program – Ben felt that if a journo had written a book, he or she was worthy of an invitation. But we never allowed a single politician to set foot in our greenroom or grace our small, booklined set – except for one: Daniel Patrick Moynihan. Ben revered the senior senator from New York as a public intellectual in the truest sense: a deep and original thinker who could introduce ideas into the public dialogue and, more importantly, translate them into public policy. As a result, Moynihan was a frequent and welcome guest, and our audience was richer for it.

A few fleeting scenes from those appearances on “Think Tank” are included in a terrific new documentary that charts the arc of Moynihan’s fascinating and important life. Titled simply “Moynihan” and directed by Joseph Dorman and Toby Perl Freilich, the nearly two-hour film tells the story of how Moynihan rose from the streets of Hell’s Kitchen to become an adviser to presidents, an ambassador to both India and the U.N., and a four-term U.S. senator. More importantly, it provides a user’s guide to how data and social science can be harnessed to inform public policy debate and effect legislation.

Moynihan’s most famous aphorism, which guided his own work and is a watchword for the film, is especially relevant today: “Everyone is entitled to his own opinion, but not his own facts.”

The film is also a powerful antidote to those who scream that America is more divided now than ever, that we are on the brink of civil war. Moynihan operated in the 1960s, and footage of urban riots, violent campus unrest, and Vietnam protests remind viewers that not so long ago, America experienced turmoil that makes today’s disruptions seem like a garden party. Campus radicals at Harvard did not simply disinvite those with whom they disagreed, they threatened to burn down Moynihan’s Cambridge home while his young family was in residence and he was at work in Washington. Snowflakes, indeed.

Moynihan saw himself as a champion of the underdog. In particular, he wanted to help what were then called “unwed mothers” – especially urban, black women. The filmmakers rightfully concentrate on his public efforts in this regard, but they also provide some personal back story to illuminate the roots of his commitment. Moynihan, born into lower-middle-class surroundings in New York, saw his own family fall into poverty when his mother was abandoned by his father – who later reappeared in California with a new wife and family. The experience taught Moynihan the importance of intact families and the role of fathers in particular. The producers do not dwell on armchair psychology, however, and the bulk of the film is devoted to Moynihan’s public life. And what a public life it was.

“The Negro Family: The Case for National Action,” commonly called “The Moynihan Report,” was this great thinker’s most consequential piece of social science. Written in 1965, it warned of how an out-of-wedlock birthrate of 25 percent among blacks threatened to create a permanent underclass. It was controversial then and it is controversial now – but today, fully 23 percent of all American families are headed by a single mother, and more than six of out 10 black families are fatherless.

Moynihan was also a showman, and the documentary revels in his carefully constructed public persona. At 6 foot 5, you could hardly miss him, and his many TV appearances are used to good effect in the film. We see him joust with William F. Buckley, Dick Cavett and Tim Russert. We’re reminded that this spellbinding speaker with the unplacable patrician accent was in reality a product of the streets of New York and a former dockworker who went to City College, before his reinvention as a Harvard don.

All in all, the result is a thoroughly entertaining portrait of a singularly consequential American.

“Moynihan” has already opened theatrically in New York and Los Angeles. It will be playing this weekend at the AFI Theater in Silver Spring, Md. – just outside the nation’s capital. For Washingtonians, it is an opportunity to be both entertained and informed – and to learn about one of the capital city’s rarest breeds: a politician who was at once a true intellectual and a world-class public performer.