What role should the Federal Reserve play in the U.S. economy? That question is at the heart of any study of the economic crisis that began in 2007 and any consideration of how to prevent further crises. A year ago the chairman of the Federal Reserve, Ben Bernanke, delivered four lectures at George Washington University, in which he argued that the Fed's response to the crisis—including its conspicuous and contentious bailouts—fell within the traditional role of a central bank. Those lectures and Mr. Bernanke's answers to some audience questions have now been edited and published in a slim volume. Pitched to a general...