Presidential candidates who think they can learn on the job are fooling themselves and deceiving the public. To be sure, every new president confronts a learning curve, for no other job fully prepares a person for the demands placed on the chief executive of the United States. But learning the details of the federal budget process is one thing; learning the methods and motives of foreign allies and adversaries is quite another.

And it is in the realm of foreign policy that presidential inexperience is most dangerous. The two great foreign policy debacles of our time — the war in Vietnam and the recent war in Iraq — followed directly from the woeful inexperience of the presidents most responsible.

Lyndon Johnson was a master of domestic politics and perhaps the greatest legislator-in-chief in American history. But he knew little about foreign affairs and less about south-east Asia. He was compelled to rely on his national security experts, who suffered from the can-do compulsion that wins promotions in the West Wing and the Pentagon.

With the exception of George Ball, the undersecretary of state, no one was willing to tell Johnson that Americanising Vietnam’s civil war was a terrible idea, that Ho Chi Minh, who had made his life’s work the ejection of foreign armies from Vietnam, would keep fighting for as long as it took to drive the Americans out. Johnson followed the bad advice of his experts, and the United States — and Vietnam — paid the price.

George W. Bush made a point of letting the media know he was studying up on foreign policy during the campaign of 2000. That alone should have been a warning, for whatever Condoleezza Rice and the team she put together told Bush in those cram sessions in the governor’s mansion couldn’t have made up for Bush’s inattention to the world during his self-admittedly misspent youth and young adulthood.

Bush’s innocence of the world didn’t seem to matter during his first several months in office, but the terrorist attacks of September 11, 2001, thrust foreign policy to the top of his agenda. The president found himself at the mercy of Dick Cheney and the cadre of neoconservatives who staffed his national security team, a group that had been itching for years to smack Saddam Hussain. They told Bush that Hussain had weapons of mass destruction or would get them soon, and Bush didn’t know the sceptical questions to ask. He blindly approved the invasion of Iraq, destabilising the heart of the Middle East and unleashing the whirlwind the United States and the world have been battling ever since.

There is no reason to think Donald Trump or any of the other candidates with little grounding in foreign affairs would do better than Johnson or Bush. (Hillary Clinton might make mistakes in foreign policy, but they wouldn’t be the mistakes of gross inexperience.) Trump has boasted that he will be guided by experts, although the names he has floated thus far have left many real experts singularly unimpressed.

The makings of a disaster

The problem with reliance on experts is that they have agendas, and the agendas only coincidentally overlap with those of the president and the country. National security experts are occupational activists; they are wired to respond to world problems with American action. In foreign policy, the hardest thing for a president to do is to say no to proposals for action. Pundits praise action; voters admire action; historians laud action. A president who says no to action is assailed as weak, irresolute or cowardly.

With the hired experts adding their voices to the chorus for action, a president without the basis for independent judgement can be stampeded into a foolish decision. Johnson couldn’t say no on Vietnam; Bush couldn’t say no in Iraq. Disaster followed.

Disaster can ruin a presidency, a country or a region. But it rarely ruins experts’ careers. Why should it? They were merely advisers. The president was the one who made the decisions. The experts skip to their next gigs: at think tanks, universities, banks, law firms, consultancies. They cash in on their recent proximity to power. Their party will win the White House again; another president, especially one unversed in foreign policy, will need experts. They’ll be back.

— Washington Post

H. W. Brands is the author of Reagan: The Life and Traitor to His Class: The Privileged Life and Radical Presidency of Franklin Delano Roosevelt, among other books. He teaches at the University of Texas at Austin.