Social security and Medicare present entirely different challenges, says this authority. But you would not know that to listen to Alan Greenspan's comments last winter. He said both programs would have to be cut. In contrast, future social security obligations can be accommodated without serious...

The two papers that make up the core of this book address what is perhaps the most fundamental question in the current debate over Social Security: whether to shift, in part or even entirely, from today's pay-as-you-go system to one that is not just funded but also privatized in the sense that...