Early on, before the campaigning begins in earnest, presidential candidates lunch with journalists in order to get acquainted. During one of these lunches, Mitt Romney was talking about the global economy and was asked why he thought some nations grew rich and others didn’t.

He said there are at least two schools of thought on this question, one associated with Jared Diamond of U.C.L.A., which emphasizes natural resources, and another associated with the Harvard historian David Landes, which emphasizes culture. Over the next several minutes, he weaved the two theories together, siding a bit more with Landes.

The answer demonstrated an ability to handle contradictory information streams. From it, you could see how Romney had managed to graduate with honors from Harvard Law School, while graduating in the top 5 percent of his class at Harvard Business School. You could see how he managed to start Bain Capital and turn it into a $4 billion firm, doubling the return on investment every single year, on average. You could see how he turned around the Salt Lake City Olympics and passed bipartisan health care reform in Massachusetts....