This theory is hard to reject because it is so hard to judge. Economists who have studied the numbers don't see much happening to productivity growth, except in the manufacture of computers. Perhaps we're so impressed by the present revolution because it's ours. And so the unexpectedly strong economy of the 1990s remains a mystery. What is not mysterious, however, is how it has led to high approval ratings for Clinton.
Presidents get more credit than they deserve when the economy is good, and more blame when it's bad.
When it comes to making economic policy, there's no substitute for being in the right place at the right time.