The gross over-confidence of politicians like Trump and Cameron might help explain inequality

In 1995 a 44-year-old man called McArthur Wheeler set out to rob two banks in Pittsburgh. In preparation for the crime he smeared his face with lemon juice. Wheeler’s bizarre logic was that since lemon juice can be used as a kind of invisible ink on paper, the liquid would also render his face invisible to the banks’ security cameras.

After the robbery police retrieved the surveillance tape and gave it to a local news channel. Wheeler was duly identified and then arrested. During his interrogation Wheeler was confused over how his cunning plan to avoid detection had failed. “But I wore the juice,” he reportedly mumbled.

Wheeler’s delusions over his own competence as a criminal inspired two US psychologists, David Dunning and Justin Kruger, to run some experiments on undergraduates at Cornell University in New York. They asked students a series of technical questions on grammar and logic and told them to estimate their scores and also estimate their rank relative to their peers.

The results suggested that some students who performed badly not only considered themselves to have done well – but also believed themselves more competent than those who performed considerably better.

Thus was established the “Dunning-Kruger effect”: the cognitive bias of illusory superiority. People who rate their talents highly sometimes just don’t grasp how incompetent they truly are.

“This is more work than in my previous life,” Donald Trump told reporters from Reuters last week in an interview to mark 100 days of predictable fiasco from the property tycoon’s White House. “I thought it would be easier. This is actually more work.” Or as the former Apprentice personality might have put it: “But I wore the juice.”

One does not have to look far in politics to find the Dunning-Kruger effect. David Cameron was once asked why he wanted to be prime minister and replied: “Because I think I’d be rather good at it.” Before the 2015 general election he solemnly warned that Britain faced an “inescapable choice – stability and strong Government with me, or chaos with Ed Miliband”.

Surveying the chaotic British political scene in 2017 many have begun to question whether this was an entirely accurate prognostication. But not Cameron. Speaking in Bangkok last week Cameron said he thought he did a “reasonable job” as Prime Minister, despite his humiliating resignation last year in the wake of the Brexit vote. And he apparently has no regrets about his decision to hold that vote. “The lack of a referendum was poisoning British politics and so I put that right,” he concluded. In Cameron’s mind the lemon juice apparently worked a treat.

In February 2016 the Conservative MP David Davis airily stated that there was “no reason” Britain could not conclude entirely new free trade agreements with its biggest foreign markets “within two years”. Trade experts regard that as catastrophically ignorant of the technical difficulties involved in constructing such complex deals. But now that the two-year Article 50 European Union divorce proceedings have been triggered and Davis is the minister for Brexit he has an opportunity to prove himself correct. Let’s hope the lemon juice is operational.

It gets worse. Research from scientists at the University of California suggests over-confidence is often taken as a signal by others of actual competence. So Trump and Cameron’s electoral success may have reflected a view among the public that they must have known what they were doing precisely because they told us so forcefully. Ditto the super-confident Brexiteers like Davis.

Such cognitive biases may not only explain why we sometimes have such inadequate political leaders but also why we have such chronically unequal societies. The flip-side of unmerited over-confidence can be unmerited under confidence. And experiments by the behavioural economist Jeffrey Butler have found that when individuals are randomly assigned high and low pay in cognitive ability tasks those who are luckier often became more confident and competitive, while the unlucky tend to grow demoralised and to inaccurately underrate the relative ability.

Perhaps this research offers a clue as to why bright and diligent kids born into disadvantage so often fail to fulfil their potential while the most prestigious jobs and political power so often seem to be monopolised by the thrusting and grotesquely over-confident sons of privilege. Or to put it another way: why the lemons rise to the top.