The Republican candidates hardly have a lock on ideological necrophilia. Bernie Sanders’s attraction to massive, government-centered programs places him squarely among populists who dismiss the need to maintain fiscal balances and end up with unsustainable government budget deficits. The plans on his campaign website would amount to an estimated $18 trillion to $30 trillion in new spending over the next 10 years. In pledging a form of European-like socialism to throngs of adoring young people, he doesn’t mention that if they were European, many of them would be unemployed and without prospects of finding a well-paying job. The bottom line: Many of his policies have already been tested, and many don’t work all that well.

In a world in which a few keystrokes on a computer can lead to a wealth of information about the track record of a particular economic or political proposal, it’s surprising that ideological necrophilia is still so common. There are many reasons why bad ideas endure, but perhaps the most important is people’s need to believe in a leader when faced with the grave anxieties and uncertainties associated with rapid change—and the demagogue’s inclination in these fragile moments to promise anything, even the discarded notions of demagogues past, in order to obtain and retain power.