Another spare, tiresome, pretentious yet simple-minded anti-American diatribe from Danish Dogma-tist Lars von Trier, the latest in his line of assaults on U.S. imperialistic cruelty and sexual-and-economic exploitation that began with “Dancer in the Dark” but took off in earnest with “Dogville,” which was the first installment in a projected trilogy of which “Manderlay” is the middle portion.

The earlier film, you’ll recall, was set in a Depression-era Colorado hamlet, into which a damsel named Gloria wandered. She was taken in by the townspeople but eventually was turned into their virtual slave, until her gangster father showed up and gave her the upper hand. In this picture Gloria (previously played by Nicole Kidman, but now by Bryce Dallas Howard) and her ruthless daddy (previously James Caan, now Willem Dafoe) come upon an old plantation in Alabama–the titular Manderlay–and discover slavery is still practiced there though it’s 1933. Infuriated at this state of affairs, Grace takes it upon herself to reform the place by force, freeing the blacks and making the whites their servants and teaching the former slaves how to run the community democratically (and the whites their new place). But though there’s some initial success, things ultimately go south, as it were, and the denouement is predictably dire. In von Trier’s version of America, doom always lurks just around the corner.

As with “Dogville,” the writer-director presents his fable on an almost empty soundstage, with chalk marks on the floor indicating locales and an occasional stick of furniture or bit of background construction to suggest place. The artificiality of the approach–which also divides the piece, rather preciously, into eight clumsily titled chapters, is as dreary this time around as the last, though the actual writing (much of it narration delivered, once more, in from the perspective of some omniscient observer–read von Trier–by John Hurt) seems slightly less arch, perhaps because the pace isn’t quite as ponderous this time around. That’s not just a factor of length, though the fact that “Manderlay” is about forty minutes shorter than “Dogville” is certainly beneficial: the tempo is a trifle less deliberate and the delivery a bit more animated, too. But all that means is that while this film is ponderous, history shows it could be worse.

But the real problem with “Manderlay” isn’t just formal; it has to do with content. Von Trier’s script, as usual, covers lots of bases–one twist takes us back to a condemnation of capital punishment, which he already dealt with in “Dancer”–but it’s basically about white guilt over slavery in this country and the fact that we can’t admit that racism is a continuing problem, simmering just beneath the surface, and that criticism of that reality (like von Trier’s, for instance) can lead to an eruption of anger and violence that unmasks the continuing but unspoken bigotry. The picture isn’t just a general condemnation of slavery as an institution; it’s a critique of the distinctively American do-goodism that claims to have addressed the evils of the system by a process of assimilation and instruction. (One of the most interesting turns the fable takes–because it has obviously topical overtones considering current Mid-East policy–involves Grace’s efforts to teach the freed slaves to decide matters democratically. Needless to say, the effort turns out badly. That extends von Trier’s indictment of American racial prejudice into a more general critique of U.S. arrogance in thinking that we can “reform” the world, and of our presumption that we inhabit some sort of moral high ground from which we can justifiably do so.)

All of which is well and good: criticism of the American past and present, of the spoken and unspoken assumptions of U.S. policy and of the baleful effects of our history and the attitudes that still exist as a result of it is entirely valid and worthwhile, from whatever source and in whatever forum, including a movie theatre. But such criticism, if expressed in cinematic form, has to be more than von Trier offers: it needs to be a flesh-and-blood drama rather than a dry dissertation, an experience that makes you viscerally feel the points it wants to make in emotional terms, not this sort of stale, arid polemic in the form of a pseudo-story. “Manderlay” fails utterly not because of the position it takes, but because of the way in which it takes it. It reduces white-hot issues to drab, dull soap-box rhetoric.

Still, some of the cast make good impressions. Howard and Dafoe recite their lines decently, even though they can’t make much of their stick characters, and Danny Glover has quiet authority as the “house Negro” Wilhelm, whose subservient pose hides something more sinister. And Isaach de Bankote is appropriately virile as the “proud” Timothy, who also turns out to be rather different than his original persona suggests. (Gloria’s misreading of the two is obviously intended to suggest U.S. blindness in seeing things as they really are.) Some of the others in the large supporting cast have their moments, too. But ultimately none of them is anything but the writer-director’s mouthpiece. Nor is the crew given much leeway, though Anthony Dod Mantle’s camerawork is as fluid as the straight-jacket approach allows. The music–a collection of somber baroque movements–is attractive, but the dirge-like quality weighs things down even more than the visuals would alone.

“Manderlay” isn’t contemptible: it represents von Trier’s effort to express his view of America. The problem is that his view is incomplete and schematic, and that he presents it in a stagy, turgid and ineffectual way. He recently announced that he’s postponing the concluding episode of the trilogy until he’s more mature. Let’s hope he does some real intellectual growing-up, and reconsiders his absurdly ascetic cinematic approach, before he takes it on.