Rediscovering <i>Homo Sapiens</i> in International Politics: Evolution and Rationality’s Missing Link

In How States Think, John Mearsheimer and Sebastian Rosato argue that the two dominant approaches to decision-making in international politics-rational choice theory and political psychology-are fundamentally flawed.Instead, they propose a model of rationality in which individuals use "credible theories" of how the world works to guide their assessments, and elites deliberate over these theories to determine foreign policy.I suggest that existing theory is too hastily rejected, and that these apparently opposing models can be reconciled by taking an evolutionary perspective-the process by which humans and human brains were built and therefore a critical, yet missing, part of the puzzle.An evolutionary perspective suggests: (1) rational choice is not always the most effective or efficient solution to decision-making problems; (2) cognitive biases are not mistakes, but adaptive "strategic instincts," which evolved because they helped us make good decisions, not bad ones; (3) these "non-rational" dispositions follow a systematic