Ray Dalio, the sixty-one-year-old founder of Bridgewater Associates, the world’s biggest hedge fund, is tall and somewhat gaunt, with an expressive, lined face, gray-blue eyes, and longish gray hair that he parts on the left side. When I met him earlier this year at his office, on the outskirts of Westport, Connecticut, he was wearing an open-necked blue shirt, gray corduroy pants, and black leather boots. He looked a bit like an aging member of a British progressive-rock group. After a few pleasantries, he grabbed a thick briefing book and shepherded me into a large conference room, where his firm was holding what he described as its weekly “What’s going on in the world?” meeting.

Of the fifty or so people present, most were clean-cut men in their twenties or thirties. Dalio sat down near the front of the room. A colleague began describing how the European Central Bank had just bought some Greek bonds from investors at a discount to their face value—a move that the speaker described as a possible precursor to an over-all restructuring of Greece’s vast debts. Dalio interrupted him. He said, “Here’s where you are being imprecise,” and then explained at length what a proper debt restructuring would entail, dismissing the E.C.B.’s move as an exercise in “kicking it down the road.”

Dalio is a “macro” investor, which means that he bets mainly on economic trends, such as changes in exchange rates, inflation, and G.D.P. growth. In search of profitable opportunities, Bridgewater buys and sells more than a hundred different financial instruments around the world—from Japanese bonds to copper futures traded in London to Brazilian currency contracts—which explains why it keeps a close eye on Greece. In 2007, Dalio predicted that the housing-and-lending boom would end badly. Later that year, he warned the Bush Administration that many of the world’s largest banks were on the verge of insolvency. In 2008, a disastrous year for many of Bridgewater’s rivals, the firm’s flagship Pure Alpha fund rose in value by nine and a half per cent after accounting for fees. Last year, the Pure Alpha fund rose forty-five per cent, the highest return of any big hedge fund. This year, it is again doing very well.

The discussion in the conference room moved on to Spain, the United Kingdom, and China, where, during the previous week, the central bank had raised interest rates in an attempt to slow inflation. Dalio said that the Chinese economy was in danger of overheating, and somebody asked how a Chinese slowdown would affect the price of oil and other commodities. Greg Jensen, Bridgewater’s co-chief executive and co-chief investment officer, who is thirty-six, said he thought that even a stuttering China would still grow fast enough to push world commodity prices upward.

Dalio asked for another opinion. From the back of the room, a young man dressed in a black sweatshirt started saying that a Chinese slowdown could have a big effect on global supply and demand. Dalio cut him off: “Are you going to answer me knowledgeably or are you going to give me a guess?” The young man, whom I will call Jack, said he would hazard an educated guess. “Don’t do that,” Dalio said. He went on, “You have a tendency to do this. . . . We’ve talked about this before.” After an awkward silence, Jack tried to defend himself, saying that he thought he had been asked to give his views. Dalio didn’t let up. Eventually, the young employee said that he would go away and do some careful calculations.

After the meeting, Dalio told me that the exchange had been typical for Bridgewater, where he encourages people to challenge one another’s views, regardless of rank, in what he calls a culture of “radical transparency.” Dalio had no qualms about upbraiding a junior employee in front of me and dozens of his colleagues. When confusions arise, he said, it is important to discuss them openly, even if that involves publicly pointing out people’s mistakes—a process he referred to as “getting in synch.” He added, “I believe that the biggest problem that humanity faces is an ego sensitivity to finding out whether one is right or wrong and identifying what one’s strengths and weaknesses are.”