Success breeds failure. Policies and practices well-suited to society at one juncture in history are often poorly suited to the world they have beneficially transformed. If you carry a good thing too far, it can turn out not to be a good thing anymore.

Case in point, one of the most successful public policies in U.S. history, the World War II GI Bill of Rights, which financed college educations for military veterans. Signed by former President Franklin Roosevelt, it embodied New Deal generosity even as its chief backers included the racist Democratic Mississippi Rep. John Rankin and the supposedly reactionary American Legion. One secret of its success, like that of Social Security, was apparent reciprocity: It provided benefits for those who made some contribution.