How Penn is putting on an act as roving ambassador
What was Sean Penn doing in Argentina anyway? Why are a movie actor and his moustache touring South America like visiting statesmen, and being welcomed with a press conference by each of the continent's presidents?
Actually, as it happens, Mr Penn is there as a visiting statesman: in January, he was appointed Haitian ambassador-at-large, the first time a non-Haitian has ever been awarded such a title.
Not that this necessarily qualifies him to comment on the status of disputed archipelagos in the South Atlantic. Indeed, you might argue that to wade into the debate over the Falkland Islands -- or "the Malvinas of Argentina", as Mr Penn appears to prefer -- is a distraction from his task.
Nevertheless, after meeting Argentinian leader Cristina Kirchner this week, the actor informed a crush of journalists that "the world today is not going to tolerate any kind of ludicrous and archaic commitment to colonialist ideology".
Later, in Uruguay, he disparaged the British RAF's plans to post Prince William to the islands as "unthinkable". The reactions of right-leaning British MPs and media outlets were predictable, with the 'Daily Mail' complaining that "the achingly trendy ex-Mr Madonna" was "shooting his mouth off". Falklands War veteran Simon Weston called him an "idiot".
The responses from different quarters show the unifying power of the tedious Hollywood liberal -- and Mr Penn is perhaps the most committed of all to the ludicrous and archaic ideology of celebrity interventionism. He has previously, for example, inserted himself into arguments surrounding Iran, Iraq and Venezuela -- though, to his credit, he did visit those places before broadcasting his views.
Politics entered the life of Mr Penn's father Leo uninvited. An actor like his son, and a decorated World War Two airman, Leo was among those blacklisted by the House Un-American Activities Committee during the 1950s for refusing to testify against his peers.
He found himself unemployable in film, and turned to the New York theatre for work, where he met Mr Penn's mother Eileen, also an actor. After Michael, the first of their three sons, was born in 1958, the couple moved to Los Angeles, where Leo became a television director.
Sean was born in August 1960. He was a volatile teenager, arguing persistently with Eileen, from whom he is said to have inherited his hard edges. In 1974, he made his first screen appearance in an episode of 'Little House on the Prairie', directed by his father. He grew up in the company of actors, including his younger brother Chris and friends Charlie Sheen and Emilio Estevez. Like them, he first emerged as part of the 'Brat Pack'.
Even during this first stage of his career, Mr Penn was known as a formidable on-set presence. He had spent two years training intensively with method acting coach Peggy Feury and, to prepare for his role, lived out of a car at the beach during the filming of 'Fast Times at Ridgemont High'. Mr Penn soon became a tabloid favourite, too, and after a brief engagement to the actress Elizabeth McGovern, he wed the young pop star Madonna in 1985. Enraged by press helicopters hovering low over the ceremony in Malibu, he found a gun and started firing at them.
The marriage proceeded in similarly tempestuous fashion: while the couple were shooting their 1986 turkey 'Shanghai Surprise' together in Macau, Mr Penn came across a photographer snooping in their hotel room, dangled the man from a ninth floor balcony by his ankles, and was arrested for attempted murder. He escaped from jail and fled the country on a jetfoil.
In 1987, he was sentenced to 60 days in jail for assaulting one of his wife's more ardent fans. The couple divorced in 1989, when Mr Penn was charged with domestic assault, after tying Madonna to a chair and beating her.
His second marriage appears to have been troubled, too, if less spectacularly so. Mr Penn and the actress Robin Wright had a daughter in 1991, and a son in 1993, marrying in 1996. But they endured a number of separations and abortive divorce filings before separating permanently in 2010.
His directorial debut, 'The Indian Runner', appeared in 1991. Subsequent films he directed are 'The Crossing Guard' (1995) and 'The Pledge' (2001).
When he returned to acting in earnest, it was to great acclaim. He was nominated for an Oscar in 1995, for his turn as doomed Death Row inmate Matthew Poncelet in 'Dead Man Walking', and finally won his first Academy Award in 2004 for the crime drama 'Mystic River'. Mr Penn won again, for 'Milk', in 2008.
By then, he was also well known for his politics. In the run-up to the Iraq war, he spent $56,000 (€43,000) on an ad in 'The Washington Post', criticising George W Bush. He visited Iraq before and after the 2003 invasion. In 2005, he travelled to Tehran to write 12,000 words for the 'San Francisco Chronicle'. He visited Venezuela to meet Hugo Chavez in 2007, and to Cuba for an audience with Raul Castro in 2008.
Following Hurricane Katrina in 2005, Mr Penn flew to New Orleans, found a boat and started fishing victims from the floods personally. When Haiti was hit by a monstrous earthquake in 2010, he swooped into the country with $1m (€765,000) in funding and no NGO experience, and founded the J/P Haitian Relief Organisation.
Detractors beware: Mr Penn does not respond well to sneers. Last year, for instance, he told CBS News that he hoped his critics would "die screaming of rectal cancer".
When the makers of 'South Park' mocked Mr Penn and his fellow Hollywood liberals in their film 'Team America', he wrote an open letter inviting them to join him on a road trip to Fallujah and Baghdad, signing off, "All best, and a sincere fuck you". He is perfectly comfortable making enemies. "I love humankind; I don't like humans," he has said. "I don't get along with people very well. I never did." (©Independent News Service)