We live in a world of broken models. To understand why world leaders can’t easily fix the sputtering global economy, you have to realize that the economic models on which the United States, Europe and China relied are collapsing. The models differ, but the breakdowns are occurring simultaneously and feed on each other. The result is that the global recovery flags, while pessimism and uncertainty mount. Take the United States. The U.S. economic model was consumer-led growth.