THE big screen's polemicist-in-chief is back. In “Capitalism: A Love Story”, Michael Moore turns his camera and loud-hailer to the identity crisis that has gripped the world's most enduring economic system. His conclusion is characteristically punchy: capitalism is inherently evil, “a system of giving and taking…mostly taking.” His line of argument is also characteristically simplistic.

Mr Moore is a showman, and his film is studded with trademark stunts. Some are funny, for instance his wrapping of crime-scene tape around the headquarters of bailed-out Wall Street firms to the bemusement of security guards. The footage of the botched attempts by experts to explain derivatives is hilarious.

His mastery of the issues is less assured. In his black-and-white world, there is no middle class, just “the people who got it all and the people who got nothing”, as one dispossessed homeowner puts it. Forget greedy borrowers, napping regulators or global economic imbalances. The recession is entirely the fault of Wall Street's robber-barons and, in a novel reading of Detroit's woes, corporate bosses who drove their companies into the ground because of, not in spite of, their determination to slim down their operations and break the power of the unions.

As in “Fahrenheit 9/11”, his film about America's response to the attacks on the World Trade Centre, Mr Moore sees conspiracies everywhere. The $700 billion bail-out after Lehman's collapse was no genuine attempt to stave off depression, but a financial coup d'état, staged by big banks. Like nefarious screen villains, the bankers “had a simple plan: to remake America to serve them.”

So busy is Mr Moore imagining such shenanigans and resorting to class-struggle theatrics, and so hectoring his tone, that he risks leaving even his fans unmoved. Tellingly, the film's first-weekend box office take was well below expectations. His biggest failure, however, is his inability to articulate a plausible alternative to the system he loathes.

He talks fuzzily of more democracy, but it is not clear what he means. He likes small, co-operatively run firms, but how that model could be made to work for multinationals is far from clear. In the end, Mr Moore fails to produce a convincing riposte to the argument that capitalism, though prone to the occasional spectacular bust, is the economic system best able to correct its own excesses.