David D. Friedman is Professor of Law at Santa Clara University, California. His rst book, The Machinery of Freedom: Guide to a Radical Capitalism, was published in 1973, remains in print and is considered a libertarian classic. His scientific interest in the future is also long-standing. Professor Friedman's web page, www.davidfriedman.com, averages more than 3,000 visitors a day and his blog, Ideas, at http: //daviddfriedman.blogspot.com receives about 400 daily visits.