Preferring common sense over abstract economic theory or unreliable historical data may seem like, well, common sense. But there’s another problem with placing too much faith in common sense — namely that although everyone thinks they know what it is, they often invoke it to reach wildly divergent conclusions. And because when something is a matter of common sense it is considered beyond dispute, these disagreements can be extraordinarily difficult to reconcile — as current political debates illustrate.
Source: The Perils of Thinking Like an Individual
-OR- The problem with complex topics that most people aren’t educated well enough to understand sufficiently but are still expected to interact with intelligently (e.g. voting on big socioeconomic issues, taking care of one’s own health, properly caring for the environment…).