Trump v Khan: the trouble with intelligence

Homer the genius: The formula above is said to correctly predict the mass of the Higgs boson.

After Sadiq Khan called him ‘ignorant’, Donald Trump challenged the mayor of London to an IQ test. To many, IQ is a byword for intelligence. How is it measured, and what does it truly mean?

A fortnight into his new job as mayor of London, Sadiq Khan was already entangled in a spat with Donald Trump. Referring to the US presidential hopeful’s divisive views on Islam, Khan labelled him ‘ignorant’. Trump responded with a challenge: ‘Let’s do an IQ test.’

Trump’s comment missed the point – as one of Khan’s aides pointed out, ‘ignorance is not the same thing as lack of intelligence.’ But it revealed something else: the value placed on IQ tests as a marker of intellectual ability. For many, it goes without saying that one’s IQ indicates one’s intelligence – that is, after all, what the ‘I’ stands for.

The importance of IQ tests is reflected in their prevalence in many societies today. Schools depend on them to spot learning difficulties in pupils. Employers use them to evaluate job applicants. Judges sometimes rule that defendants with low IQs are not fit to stand trial.

Yet the tests are not without controversy. They emerged, over a century ago, from attempts to quantify a person’s innate intelligence. But experts have long questioned whether such a thing can be measured with a number – or if it even exists.

This view was expressed early on by IQ pioneer Alfred Binet, who stressed the great diversity of intelligence. Decades later, the American psychologist Howard Gardner developed a ‘theory of multiple intelligences’. He argued that physical, social and musical skills should be classed alongside verbal and logical aptitudes as ‘intelligences’.

It is now widely accepted that IQ tests assess specific skills, such as spatial reasoning and powers of analysis. And it seems that these are determined not only by innate ability, but also by such factors as education. Experts point to the Flynn effect, whereby IQ test scores have increased since the 1930s. This rise is too quick to be explained by genetic evolution – there must be external causes at work.

Interpreting IQ is a messy business. Test scores are often misunderstood. Is it time we stopped using them?

Bright sparks

Yes, say some. IQ is not only misleading: it can be dangerous. The system measures assets – say, range of vocabulary – that are more prevalent among the wealthy and educated, and passes them off as ‘intelligence’. As such, it can lend weight to racist and classist theories. It is high time we took a more nuanced view of intelligence.

IQ is not the be all and end all, agree others. Other assets, such as social awareness and work ethic, are equally crucial predictors of ‘success’. But it is still an effective measure of important skills. Tests can help a teacher work out whether a pupil needs special help in certain areas, for example. They are flawed, yes, but still useful.

You Decide

  1. Are tests important in life? (All tests, not just IQ-related ones.)
  2. Boris Johnson once said that some people are too stupid to succeed in life. Is he right?


  1. Come up with your own definition of intelligence. Share it with the class, and see whether they agree.
  2. Take the IQ test in the Become An Expert section. Is it a good measure of intelligence? Write down your thoughts in 300 words.

Some People Say...

“Intelligence is the ability to adapt to change.”

Stephen Hawking

What do you think?

Q & A

Am I ever going to have to take an IQ test?
Depends on where you live and what you want to do in life. For example, IQ tests are more common in the American education system than the British one. They also form a part of applications for certain types of job, especially grad schemes. But in other fields – such as manual work or the creative industries – they are less relevant.
I flunked my last IQ test. Is that bad?
The idea that IQ tests are the sole (or best) way to measure intelligence is falling out of favour. This is partly due to general problems with tests: what if you’re just having a bad day? Also, the notion that the specific skills addressed in IQ tests constitute intelligence is being challenged. So don’t lose hope – your score doesn’t mean you can’t achieve great things.

Word Watch

Not the same
In other words Trump was ignorant of what ‘ignorant’ means.
IQ tests
There are various tests, suited to different purposes. Some are aimed at specific age groups, for example.
Stands for
The ‘Q’ is for ‘quotient’, meaning ‘amount’.
A UK court is currently deciding whether two Trinidadian prisoners should be taken off death row, on account of their exceptionally low IQs. See Become An Expert.
Alfred Binet
(1857-1911) French psychologist. He invented one of the earliest IQ tests, a modified version of which is still used. Contrary to many other early adopters of the tests, he was vocal about their limitations, arguing that intelligence cannot be reduced to a number.
Flynn effect
Named after academic Jim Flynn, who made it widely known. Proposed explanations include the spread of education and improved nutrition. See Become An Expert.
The writer Jason Richwine gained notoriety when he published a paper arguing that their lower IQ scores show American Hispanics to be stupider than native-born whites. The controversy caused him to lose his job with a think tank.


PDF Download

Please click on "Print view" at the top of the page to see a print friendly version of the article.