“You can’t opt in and then out of offering film tax credits,” said producer David Hoberman (“The Fighter” and “The Proposal”) referring to Gov. Deval Patrick’s plan to cap the film tax credit at $50 million – down from around $125 million. “If you’re going to stay in the business of making movies, then stay in the business,” said the man behind Disney’s Mandeville Films, who was at Suffolk University yesterday leading a screenwriting workshop for 50 undergrads. “You need to develop infrastructure and talent. It takes time for people to feel secure enough to stay in Massachusetts if they know there’s going to be work,” he said.

Martin Scorsese’s suspense thriller, “Shutter Island,” led the North American box office for a second consecutive weekend on Sunday, fending off strong debuts from the comedy “Cop Out” and horror remake “The Crazies.” Leonardo DiCaprio, who has collaborated previously with Scorsese, stars in the picture as a federal marshal stranded at a prison hospital for the criminally insane off the coast of Massachusetts in 1954.

If Professors Fitzgerald and Enrich stepped out of their offices at Northeastern University and sauntered to where wage earners are struggling to meet mortgage payments, they might reassess the value of “transient’’ jobs. In Dorchester and South Boston during the summer production season, on the set of the “The Zookeeper,’’ just one of the movies then in production, they would have seen many employees who were happy with their transient union jobs. At the Franklin Park Zoo set, where I worked, there were more than 100 employees for a number of months. They included carpenters, plasterers, painters, greenspersons, Teamsters, dressers, electricians, and laborers, many who had been laid off from other industries.

Joe Maiella, president of the Massachusetts Production Coalition, an unexpected attendee at a State House briefing held by critics of film industry tax breaks, took on the leading opponent, Rep. Steve D’Amico, challenging his facts and offering his version of “what’s true” about film production credits.

Word outta Tinseltown is that the Cambridge homey will star as Robert F. Kennedy in a biopic about the slain senator.

The Dennis Lehane novel on which “Shutter Island” is based takes place in Massachusetts, and the film was shot almost entirely in the Bay State. “We looked at Massachusetts, Connecticut and Rhode Island — searching for incentives so we would get a bang for the buck,” says location manager Robin Citrin. “Massachusetts had good ones, plus a lot of abandoned mental hospitals, some of them with incredible architecture.”

This film presence can offer a myriad of options to VES graduates like Horovitz who decide to remain in the area. Upon graduating, Horovitz became the first Teaching Fellow of VES 50: Fundamentals of Filmmaking. But due to the Massachusetts Film Tax Credit luring major studios to shoot in Boston, he also has had the opportunity to work on commercial film. “It’s great,” said Horowitz. “I’ve TA-ed here, and on Fridays I’ll PA [work as a Production Assistant] on a hundred-million-dollar movie.”

Massachusetts-made SHUTTER ISLAND is the number one movie in America.

The growth of the film industry here ought to prompt a wider discussion about general tax policy. It is the film industry that is in focus right now. But it is actually about every industry. It is the private sector that creates the jobs that produce the tax revenue that is the lifeblood of government. If government keeps raising the price of doing business here, it will ultimately collect less and less.

It’s nice to spot Leonardo DiCaprio in Nahant or Bruce Willis in Lynn, but Massachusetts House Speaker Robert DeLeo said business is the biggest reason to bring Hollywood to the Bay State. His view is underscored by a recent University of Massachusetts study concluding the state’s efforts to lure Hollywood stars has transformed Massachusetts into one of the nation’s fastest-growing locations for film and television production with a 117 percent growth in motion picture and video production jobs in the state between 2005 and 2008.

Oddly, Professor Enrich makes no reference to UMass’ recently published, independent, 18 month study on the local economic impact of the MA film industry since 2006. According to that study, nearly 7,000 jobs were created in 2008 alone. Even if you attribute only 75% of those jobs to the credit, the cost-per-job is just $18,000. The professor was correct about one thing, film jobs pay an average annual salary of $68,000. Hardly a “losing bargain.”

Just in the past couple of years, the local area has hosted several movie projects. Scenes from “Bride Wars,” starring Anne Hathaway and Kate Hudson, were filmed in Salem. Parts of “The Proposal,” starring Sandra Bullock, Ryan Reynolds and Betty White, were filmed in Beverly and Manchester. “The Company Men,” starring Ben Affleck, Kevin Costner and Tommy Lee Jones, features scenes shot in Marblehead. Capping the film tax credit isn’t so much about making those in the film industry angry. It’s about a short-term gain that will very likely create a long-term loss.

This incentive is not just about actors, directors, producers or studio owners who benefit from the program. It’s about local businesses and workers, some in sectors that have been particularly hard hit by the recession, such as construction and transportation. Jobs and private-sector economic activity are what produce the long-term, sustainable tax revenue that the state desperately needs. So while Essex reaped $150,000 as a town from “Grown Ups” using Centennial Grove, it’s more notable that the summer-long film work injected an estimated $1 million or more into the Essex private-sector economy. It would be foolish, not to mention expensive, to drive that activity to other states.

A new study from the University of Massachusetts at Boston confirms what local residents have been noticing in recent years: The state is one of the fastest-growing locations for film and television production. So the worst thing government could do is discourage that growth.

Local officials fear that Gov. Deval Patrick’s proposal to scale back a tax credit for movie producers to make films in Massachusetts would set back plans for the construction of a $300 million motion picture studio complex at the former South Weymouth Naval Air Station.

Here’s a Massachusetts movie sweep that’s probably the first of its kind: I picked up this week’s Rolling Stone (the one with a heavily-tattooed Lil Wayne on the cover), and all of the movie reviews inside were of Massachusetts-set films.