Are differences in IQ to blame for income inequality?

London Mayor Boris Johnson sparks a debate over the relationship between wealth and smarts

Boris Johnson
(Image credit: (Oli Scarff/Getty Images))

Last week, London Mayor Boris Johnson made a very controversial assertion that differences in IQ levels help explain income inequality. Here are his remarks:

Whatever you may think of the value of IQ tests, it is surely relevant to a conversation about equality that as many as 16 percent of our species have an IQ below 85, while about 2 percent have an IQ above 130. The harder you shake the pack, the easier it will be for some cornflakes to get to the top.

And for one reason or another — boardroom greed or, as I am assured, the natural and god-given talent of boardroom inhabitants — the income gap between the top cornflakes and the bottom cornflakes is getting wider than ever. I stress: I don't believe that economic equality is possible; indeed, some measure of inequality is essential for the spirit of envy and keeping up with the Joneses that is, like greed, a valuable spur to economic activity. [via The Telegraph]

This started a massive public argument not only in England, but in economic circles generally. While some claimed that Johnson was "telling it like it is," Deputy Prime Minister Nick Clegg condemned the mayor's remarks as "careless elitism." Others questioned the concept of IQ altogether.

On Tuesday, radio talk show host Nick Ferrari asked Johnson some impromptu questions from an IQ test. Johnson did not fare so well.

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Question 1: A man builds a house with four sides of rectangular construction, each side having a southern exposure. A big bear comes along. What color is the bear?

The mayor's answer: Johnson said the bear was probably brown. The answer is white because the house must be at the north pole to have four south-facing walls.

Question 2: How many apples would you have if you took two apples from three apples?

The mayor's answer: Johnson said, "Loads of apples." He then changed his answer to one apple. But the answer is two apples — if you take two apples, then you have two apples.

Question 3: I went to bed at eight o'clock in the evening and wound up my clock and set the alarm to sound at nine o'clock in the morning. How many hours sleep would I get?

The mayor's answer: The mayor refused to answer. The right answer is one hour, as a wind-up alarm clock cannot differentiate between AM and PM. [Telegraph]

To be fair, those are some pretty tough questions, especially when they're thrown at you with the expectation of an immediate answer.

But the real question is whether a person's IQ score even matters. IQ is not necessarily even a very good measure of how smart you are. Intelligence — and the ability to succeed in life — is far more multi-dimensional than IQ.

According to professor Howard Gardner of Harvard University, intelligence can be measured along seven different dimensions: Visual-spatial, bodily-kinesthetic, musical, social, emotional, linguistic, and logical-mathematical. At most, an IQ test tries to measure three of these: Visual-spatial, linguistic, and logical-mathematical. Some people see even more dimensions — creativity, memory and retention, reaction time, etc.

Furthermore, scientists have already investigated the link that Johnson made between IQ and inequality. A 2007 study in the journal Intelligence found that although people with higher IQs tend to earn a little more, there is no direct correlation between IQ and wealth:


Sorry, Boris. IQ is not a satisfying explanation for wealth inequality.

Indeed, there is a much stronger correlation — as measured by the famous Stanford Marshmallow Experiment — between self-control and wealth.

The experiment gave children a choice between one marshmallow placed in front of them, or two marshmallows if they could wait for 15 minutes. The study found that children who took the first marshmallow grew up to be more likely to have multiple health problems, have a criminal record, be a drug addict, be a single parent, and have less wealth. The child who exercised self-control and waited 15 minutes was more likely to flourish.

So self-control is an important attribute for success in life. But can it be taught? Is that the best way to tackle the growing inequality between rich and poor that is emerging in Western countries?

Lots of studies have since shown that children are able to develop self-control strategies, and that self-control is like a muscle that needs training to develop its full strength. A 2012 paper by German academics concluded:

Because self-control skills can be trained, early life interventions are possible, with potentially large welfare benefits. Although individuals at all levels of the self-control scale seem to benefit from increases in self-control ability, scarce resources may be warranted to identify at-risk children and youth and to direct resources for interventions to them. []

In other words, like most questions of policy, it's a complicated issue. Unfortunately, some politicians are only too happy to simplify matters by suggesting poorer people just aren't very smart.

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John Aziz is the economics and business correspondent at He is also an associate editor at Previously his work has appeared on Business Insider, Zero Hedge, and Noahpinion.