When The Facts Change I Change

This quip is widely attributed to Keynes, reportedly delivered as a retort during a debate when he was challenged for reversing a previous position. While the exact occasion is unverified, it is consistent with Keynes's intellectual temperament: he revised his views openly throughout his career, most famously abandoning aspects of classical monetary theory while developing the arguments of The General Theory (1936). The remark has since become a touchstone for empirical, evidence-responsive thinking.