The main competition at this festival might be compared to an exclusive club with a significant number of permanent members. (A gentleman's club, mainly, since shockingly few women - none this year - are invited to join.) Some filmmakers pass through an initiation period in satellite programs like Un Certain Regard and the Directors' Fortnight, while others vault right onto the main stage, but it is remarkable how many of them, once they are voted in, keep showing up year after year.

Not only do these masters face off against one another in the annual tussle for the Palme d'Or, but they also serve on the juries that award it. Emir Kusturica, the president of this year's jury, had a film in competition last year (and won the top prize 10 years ago). Atom Egoyan, whose "Where the Truth Lies" is competing this year, was on the jury in 1996, when David Cronenberg's "Crash" was in competition. "A History of Violence," Mr. Cronenberg's new film, is a current entry, and he was jury president in 1999, when the top prize went to "Rosetta," directed by Belgium's Jean-Pierre and Luc Dardenne, who are back this time with a movie called "The Child" (not to be confused with "The Son," which was their entry three years ago).

These repeated visits can have the effect of burnishing a director's reputation. Surely, for example, "A History of Violence," a deceptively accessible, brilliantly booby-trapped thriller, is likely to excite even viewers who have been perplexed or repelled by Mr. Cronenberg's past work, and also to satisfy his die-hard admirers (a group well represented among English-language critics here).

But then there is the case of Lars von Trier, who won the Grand Prize (a runner-up honor, despite its name) for "Breaking the Waves" in 1996 and the Palme four years later for "Dancer in the Dark." In 2003 he arrived with "Dogville," the first film in a projected trilogy set in the United States during the Great Depression and shot on a vast, almost barren soundstage in Scandinavia. (He left without a prize.) Now he is back with the second installment, called "Manderlay," after a song by Kurt Weill and Bertolt Brecht. It stars Bryce Dallas Howard in the role originated by Nicole Kidman, a gangster's daughter named Grace.

"Dogville," a harsh allegory of communal intolerance, enraged some American critics, who accused Mr. von Trier of trashing a country he had never visited. Its perceived anti-Americanism found predictable favor with quite a few Europeans, and that debate may well replay itself this year. Except that "Dogville" was, even to its enemies, a powerful and provocative enough film to elicit a defensive reaction. "Manderlay," in contrast, a bizarre interpretation of American racial history overlaid with ill-digested Nietzschean ideas about slavery and domination, is too silly to deserve serious opprobrium.

Mr. von Trier loves to court controversy, and in the past he has inspired some vital debates with his confrontational, formally daring exercises in cinematic sadomasochism. This is more like a bright, undisciplined undergraduate's term paper combined with a child's tantrum. Mr. von Trier gleefully attacks the moral arrogance of American liberals (the phrase "politically correct" even appears anachronistically in the script), but all he offers in its place is his own artistic self-regard, which is starting to grow tiresome.

Thankfully, in addition to the old guard, the first half of the Cannes Film Festival (which concludes on Saturday) presented some new faces, whose first forays into competition met with mixed reactions but who also performed the valuable service of opening up fresh topics of debate.

Carlos Reygadas is a Mexican director in his mid-30's whose first film, "Japón," played in the Directors' Fortnight in 2002. His second, "Battle in Heaven" is ambitious in a way that courts strong responses, both positive and negative, and is perhaps not entirely in control of its ambition. The main character is a stocky, plain-looking chauffeur who, along with his wife, has committed a senseless crime. He also initiates a sexual relationship with his employer's daughter, and the story moves, slowly and heavily, toward an inevitably grim conclusion.

Whether Mr. Reygadas achieves the profundity he aims for is open to dispute (a dispute I am having with myself at this moment), but there is no question that he has a gift for raw, strange and beautiful compositions, and for infusing everyday life in Mexico City with an almost metaphysical terror.

Mr. Reygadas represents a cinema of difficulty - a tradition that challenges conventions of psychological realism and emotional transparency. Marco Tullio Giordana, at 54 still a relatively new face here, can be said to represent an opposing tendency, one of humanistic social concern. In 2003, "The Best of Youth," his glorious six-hour mini-series about Italy in the last decades of the 20th century, was shown out of competition, earning his new film, "Once You're Born You Can Never Hide," a chance at the Palme.

If "Battle in Heaven" risks obscurity, "Once You're Born" risks sentimentality, and it is a risk some critics have been unwilling to indulge. (In the poll of French critics published in the trade newspaper Film Français, it had the lowest score of any competition film shown so far.) Using both professional and nonprofessional actors (including a remarkably gifted child named Matteo Gadola), Mr. Giordana tells the story of a young boy, the son of a prosperous factory owner, who is lost at sea and rescued by a boat carrying illegal immigrants into Italy. He befriends two of them, a brother and sister from Romania, and in his efforts to help them confronts some of the contradictions facing Italian society - and indeed much of Europe - today.

Many of the European films in Cannes that address problems of poverty, racism and social conflict do so in a harsh, austere, punishing manner. "Once You're Born," with its tenderness and generosity of spirit, is different, and this may have hardened some hearts against it. But such humanism, Mr. Giordana remarked this morning as he sat in a beachside cafe behind the Palais des Festivals, "is part of the DNA of the Italian cinematic tradition." He is a worthy bearer of that inheritance - bringing it to this Cannes festival and, one hopes, to many more in the future.