A similar sequence seems to have happened in Milton Friedman’s advocacy of laissez-faire. In the aftermath of the Great Depression, there were many people saying that markets can never work. Friedman had the intellectual courage to say that markets can too work, and his showman’s flair combined with his ability to marshal evidence made him the best spokesman for the virtues of free markets since Adam Smith. But he slipped all too easily into claiming both that markets always work and that only markets work. It’s extremely hard to find cases in which Friedman acknowledged the possibility that markets could go wrong, or that government intervention could serve a useful purpose.

Friedman’s laissez-faire absolutism contributed to an intellectual climate in which faith in markets and disdain for government often trumps the evidence. Developing countries rushed to open up their capital markets, despite warnings that this might expose them to financial crises; then, when the crises duly arrived, many observers blamed the countries’ governments, not the instability of international capital flows. Electricity deregulation proceeded despite clear warnings that monopoly power might be a problem; in fact, even as the California electricity crisis was happening, most commentators dismissed concerns about price-rigging as wild conspiracy theories. Conservatives continue to insist that the free market is the answer to the health care crisis, in the teeth of overwhelming evidence to the contrary.