“Because economists can’t carry out experiments, economics is not a science. Discuss.” A classic exam question, but the premise is false: economists have been experimenting for decades. In the 1970s, John Kagel and Raymond Battalio tested the economic rationality of animals. For example, they plied rats with root beer (yum) and tonic water (yuck), varying the effort required to access either drink to see how they coped with changing prices. The rats turned out to be perfect rational consumers and could even manage a budget, which is more than can be said for most economics students.