Paul Krugman — Nobel Laureate economist, #5 on Prospect magazine’s 2015 list of the world’s top “thinkers” — gives us powerful advice about the climate policy debate in his August 12 NYT op-ed (similar to this from a February column).
Here’s how I would approach the issue: by asking how we know that a modeling approach is truly useful. The answer, I’d suggest, is that we look for surprising successful predictions. General relativity got its big boost when light did, in fact, bend as predicted. The theory of a natural rate of unemployment got a big boost when the Phillips curve turned into clockwise spirals, as predicted, during the stagflation of the 1970s.
So has there been anything like that in recent years? …Were there any interesting predictions from … models that were validated by events?
In fact he is discussing his own field, macroeconomics — but this insight has deep roots in the philosophy of science and applies as well to climate science. Predictions are the gold standard for validating theories. In The Structure of Scientific Revolutions (1962) Thomas Kuhn described failed predictions that undermined dominant paradigms (e.g., the Michelson–Morley experiment) and successful predictions that helped establish new paradigms (e.g., the orbit of Mercury). He said…