Franklin Delano Roosevelt knew a thing or two about fear. When FDR raised his hand to take the oath that would make him the thirty-second president of the United States, fear had settled like a thick gray fog across Washington. It was the very bottom of the Great Depression. Banks were falling like dominoes, and more than half the industrial production of the United States had evaporated. Prices for farm products had collapsed, one in four workers was unemployed, and two million Americans were homeless.

This was the country whose care was about to be entrusted to a partially paralyzed man who had narrowly escaped assassination only a month before. Eleanor Roosevelt understandably described her husband’s inauguration as “terrifying.”

In his first address as president, Roosevelt spoke directly to the mood of the day. “I am certain that my fellow Americans expect that on my induction into the presidency I will address them with a candor and a decision which the present situation of our nation impels,” he began. “This is pre-eminently the time to speak the truth, the whole truth, frankly and boldly. Nor need we shrink from honestly facing conditions in our country today. This great nation will endure as it has endured, will revive and will prosper. So, first of all, let me assert my firm belief that the only thing we have to fear is fear itself—nameless, unreasoning, unjustified terror which paralyzes needed efforts to convert retreat into advance.”

Of course Roosevelt knew there were plenty of things to fear aside from fear itself. But he also knew that as serious as the nation’s problems were, “unreasoning fear” would make things far worse by eroding faith in liberal democracy and convincing people to embrace the mad dreams of communism and fascism. The Great Depression could hurt the United States. But fear could destroy it.

It’s an insight older than the United States itself. Roosevelt’s line was lifted from Henry David Thoreau, and Thoreau in turn got it from Michel de Montaigne, who wrote “the thing I fear most is fear” more than three and a half centuries ago.

Fear can be a constructive emotion. When we worry about a risk, we pay more attention to it and take action where warranted. Fear keeps us alive and thriving. It’s no exaggeration to say that our species owes its very existence to fear. But “unreasoning fear” is another matter. It was unreasoning fear that could have destroyed the United States in the Great Depression. It was unreasoning fear that killed 1,595 people by convincing them to abandon planes for cars after the September 11 attacks. And it is the growing presence of unreasoning fear in all the countries of the Western world that is causing us to make increasingly foolish decisions in dealing with the risks we face every day.

Daniel Gardner, The Science of Fear