Joseph E. Stiglitz writes for The New York Times: “The controversy over the choice of the next head of the Federal Reserve has become unusually heated. The country is fortunate to have an enormously qualified candidate: the Fed’s current vice chairwoman, Janet L. Yellen. There is concern that the president might turn to another candidate, Lawrence H. Summers. Since I have worked closely with both of these individuals for more than three decades, both inside and outside of government, I have perhaps a distinct perspective.”