In his first inaugural address, President Franklin Delano Roosevelt declared, “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.”

FDR was wrong. Far worse than nameless, unreasoning, unjustified terror is nameless, unreasoning, unjustified optimism which leads to catastrophic blunders that would not have occurred if potential costs and risks had been properly weighed in advance. The greatest thing we have to fear is … optimism itself.

Excessive optimism has ruined many individual business investments, investment portfolios, and romantic relationships. But individual failures are limited in their impact on society. Not so, the blunders of political leaders who wreck their nations or empires by overestimating their chances of success.

What was Napoleon thinking, when he invaded Russia? What was Hitler thinking, when he repeated Napoleon’s mistake?

The Great Leap Forward of 1958-1962 is thought to have resulted in the deaths of as many as 45 million Chinese because of famine, caused inadvertently by Mao’s imbecilic scheme of catching up rapidly with the West in industry through a crash program including the construction of primitive backyard steel furnaces.

Are autocrats more prone to these kinds of disastrous blunders? One would have to be very brave to question a proposal made by the Fuhrer or the Great Helmsman.

But unchecked optimism can drive democracies to disaster as well. The catastrophes that have befallen the U.S. and the world in the last generation all have their roots in excessive, even utopian, optimism.

The invasion of Iraq by President George W. Bush in 2003 may go down in history as the single stupidest blunder in the annals of U.S. foreign policy. The architects of the Iraq War believed that once Saddam Hussein was removed from power, a functioning Iraqi democracy could be set up in short order, making a prolonged occupation of the country by U.S. and allied forces unnecessary. Post-Saddam Iraq would pay for its own reconstruction, with revenues from oil sales.

Instead, the country disintegrated into a cauldron of ethnic warfare, which, merging with the chaos of civil war in Syria, has enabled the rise of the would-be Caliphate, the Islamic state, which has sought to replace al-Qaeda as the leader of global Salafist Sunni jihadism. Ignoring the warnings of many Middle East experts, George W. Bush lit a fuse that has blown up much of the Arab world.

The optimism of America’s economic policy establishment has been equally extreme and out of touch with reality. In the late 1990s, many policymakers and pundits mistook a bubble in tech stocks for a new age of sustained high growth. The stock market crash of 2001 hardly dented irrational elite optimism. Between 2001 and the crash that triggered the Great Recession in 2008, many analysts were convinced that the world economy had entered what was called “the Great Moderation,” an age of low interest rates and high and stable growth. This turned out to be merely the calm before a far greater storm, which took the shape of the worst global economic crisis since the Great Depression.

The bias in favor of exaggerating chances of success in war and “rosy scenarios” in economic policy seems to be shared by dictatorships and democracies alike. Individual leaders, whether they rose to power by election or force, are likely to have inflated notions of their personal ability to achieve great deeds. In democracies as in autocracies, the leaders are likely to be surrounded by yes-men and yes-women, afraid to anger the leader by bearing bad news.

Formal checks and balances, like those of the U.S. constitution, with its system of separated powers, don’t adequately counteract optimistic groupthink. All too often, policymakers in the executive branch, Congress and the judiciary get swept up in the same madness, as happened when Congress approved Bush’s doomed war in Iraq in the aftermath of the al-Qaeda attacks of 9/11. And America’s elaborate system of checks and balances did not prevent those few and brave economic experts who warned that the bubble of the 2000s was unsustainable, until it was too late. Mere formal institutional checks are easily swept aside, when a mob — including an elite mob — is collectively deranged.

In medieval monarchies, the court jester was supposed to have immunity from punishment, if he spoke truth to power. Whether this was the case in fact I am inclined to doubt.

Senior statesmen with surplus gravitas can sometimes succeed in talking down over-optimistic policymakers. With other students at Yale in the 1980s, I was invited to a conversation with former German Chancellor Helmut Schmidt. Asked to name the most impressive foreign statesman he had met, Schmidt came up with a surprising choice — Soviet minister of foreign affairs Andrei Gromyko.

From his wielding of the Soviet veto at the UN Security Council, Gromyko had obtained the nickname Mr. Nyet or Mr. No. According to Schmidt, Gromyko was also known for his success at home in repeatedly blocking ill-conceived initiatives by the Soviet Politburo. The punchline? Gromyko was in the hospital, when the Politburo made the decision to invade Afghanistan in 1979.

When asked what job he would accept in the newly-elected Reagan administration, the conservative editor William F. Buckley, Jr., replied, “Ventriloquist.” The Cabinet post that needs to be filled, however, is neither Ventriloquist nor Echo. It is the appointee sometimes described, with apologies to James Bond, as “Dr. No,” the official whose sole function is to say an over-optimistic president or prime minister: “Are you crazy? Have you completely lost your mind? Are you a total idiot? Don’t even think it. Forget about that stupid idea right now and never raise it again.”

Volunteers to be Dr. No in the next administration may apply to the Clinton and Trump campaigns. I would guess that there will not be much competition for the job. •