What Social Science Does—and Doesn’t—Know
Introduction & Interesting Excerpts
In early 2009, the United States was engaged in an intense public debate over a proposed $800 billion stimulus bill designed to boost economic activity through government borrowing and spending. James Buchanan, Edward Prescott, Vernon Smith, and Gary Becker, all Nobel laureates in economics, argued that while the stimulus might be an important emergency measure, it would fail to improve economic performance. Nobel laureates Paul Krugman and Joseph Stiglitz, on the other hand, argued that the stimulus would improve the economy and indeed that it should be bigger. Fierce debates can be found in frontier areas of all the sciences, of course, but this was as if, on the night before the Apollo moon launch, half of the world’s Nobel laureates in physics were asserting that rockets couldn’t reach the moon and the other half were saying that they could. Prior to the launch of the stimulus program, the only thing that anyone could conclude with high confidence was that several Nobelists would be wrong about it.
But the situation was even worse: it was clear that we wouldn’t know which economists were right even after the fact. Suppose that on February 1, 2009, Famous Economist X had predicted: “In two years, unemployment will be about 8 percent if we pass the stimulus bill, but about 10 percent if we don’t.” What do you think would happen when 2011 rolled around and unemployment was still at 10 percent, despite the passage of the bill? It’s a safe bet that Professor X would say something like: “Yes, but other conditions deteriorated faster than anticipated, so if we hadn’t passed the stimulus bill, unemployment would have been more like 12 percent. So I was right: the bill reduced unemployment by about 2 percent.”
Another way of putting the problem is that we have no reliable way to measure counterfactuals—that is, to know what would have happened had we not executed some policy—because so many other factors influence the outcome. This seemingly narrow problem is central to our continuing inability to transform social sciences into actual sciences. Unlike physics or biology, the social sciences have not demonstrated the capacity to produce a substantial body of useful, nonobvious, and reliable predictive rules about what they study—that is, human social behavior, including the impact of proposed government programs.
The missing ingredient is controlled experimentation, which is what allows science positively to settle certain kinds of debates. How do we know that our physical theories concerning the wing are true? In the end, not because of equations on blackboards or compelling speeches by famous physicists but because airplanes stay up. Social scientists may make claims as fascinating and counterintuitive as the proposition that a heavy piece of machinery can fly, but these claims are frequently untested by experiment, which means that debates like the one in 2009 will never be settled. For decades to come, we will continue to be lectured by what are, in effect, Keynesian and non-Keynesian economists.