Martin Scorsese's Taxi Driver has long been seen as a controversial masterpiece, a searing time capsule of New York City scraping bottom, and a high point in the fashion history of Mohawk haircuts. Now it turns out that on top of all those things, it's also a stealth fighter in the battle to unleash the forces of free market capitalism. This comes from Columbia University economist and Nobel laureate Robert Mundell, who has revealed to the world a theory that might be called wildly speculative and more than a little tasteless--in a word, Screengrabian. It has to do with the infamous effects of the film on John Hinckley, who developed an obsession with Jodie Foster based on her performance in the movie and watched it over and over, immersing himself in the sight of Robert De Niro's Travis Bickle preparing to assassinate a presidential candidate before switching gears and turning his guns on the Foster character's exploiters. Eventually, in the spring of 1981, Hinckley himself shot Ronald Reagan, then less than two months into his presidency.

Here's where it gets good. Although many remember Reagan as having been supernaturally unstoppable during the early years of his presidency, he was already facing major opposition, both in Congress and from the public at large, to parts of his economic plan. But then Hinckley showed up. "According to Mundell," writes the Financial Times of London, "the wave of sympathy for Reagan that was engendered by the assassination attempt deterred Democrats in Congress from voting against his proposed tax cuts. Because of this accident of history, the US administered a big fiscal stimulus at the same time that Paul Volcker at the Federal Reserve was administering tight money. This, for Mundell, was vital in creating the era of prosperity that followed." On the basis of this development, Mindell doesn't think that the movie's historical economic importance can be overstated. "Taxi Driver is the most important movie ever made from the standpoint of creating GDP," he's said. "It's the movie that made the Reagan revolution possible. That movie was indirectly responsible for adding between $5trn and $15trn of output to the US economy." At least we think it was indirect. Stay tuned for our next chapter, in which Oliver Stone arrives waving photos of Milton Friedman and Martin Scorsese performing script doctoring chores while crouching in the grassy knoll.