New York city's Museum of Modern Art (MOMA) is to modern art what the Oxford English Dictionary is to English the last word in authority. But when your job is to stabilize the quarrelsome, shape-shifting course of modern art history, authority is a tricky thing. John Elderfield, 61, knows all about that. As moma's chief curator of painting and sculpture, with final say over what hangs in the museum's galleries, he has carefully expanded a story that was threatening to harden into a narrow orthodoxy. That is why the recent rehanging of moma's permanent collection was one of the most hotly anticipated art-world events in years. Was Picasso down? (No.) Jasper Johns up? (Yes!) Would lesser-known Latin Americans get more space? (Yes.) Would the big names of the '80s make it through the door? (A select few.) "The history of modern art is not a single path," he says. "It's more like a democracy, full of different constituencies trying to convince the world that they're the ones who count." The world, you might say, and Elderfield.