Measuring the Mind

'Intelligence' has long been a contested and dangerous concept. What is it? Who has it? Can it be changed? How do we know?

In his new book, Smart, David Brydan analyses how ideas about the intellect have ebbed and flowed throughout the past two centuries. Here he outlines some of his findings.

Questions by Peter Moore

Unseen Histories

It is common to come across descriptions from the Georgian Age of certain individuals being ‘in possession of great genius’ for a distinct subject or task. You argue that this mode of thought was quite different to the concept of general intelligence that emerged at the end of the nineteenth century. Is that right?

David Brydan

There were different ways of thinking about intelligence before the nineteenth century. 'Genius' was one of them, used to label incredible abilities in certain fields but also linked to Romantic ideas of madness.

Other English-language terms also overlapped with later ideas about intelligence – 'talent', 'wit', and so on. But their meaning always stretched further than how 'intelligence' would come be understood, often involving ideas about character, temperament or spirituality.

The modern idea of intelligence that emerged at the end of the nineteenth century stripped all that away. Now it was understood as a singular, measurable quality; clustered around specific mental skills such as verbal or numerical reasoning; possessed by some individuals or groups more than others; and crucial to the success of individuals and the progress of civilisation.

Unseen Histories

The cold, quantitative analytical work of figures like Francis Galton at the end of the nineteenth and beginning of the twentieth century was the time when humans were crudely divided into groups. Was this the moment when the idea of ‘intellect’ gained ground?

David Brydan

To follow on from the previous question, Galton also often preferred the term 'genius'. His contribution was to take the relatively new, limited and hierarchical idea of intelligence, which had been growing in popularity over previous decades, and to subject it to scientific study.

He studied the characteristics of individuals, but often thought in terms of the differences between human groups – social classes, nationalities, genders, and races. Other psychologists picked up where he left off, spawning the science of intelligence at the start of the twentieth century.

The technologies of testing that emerged from this science then spread rapidly across Western societies, through new systems of mass education and management theory. These completely reshaped the way ordinary people thought about intelligence and its importance.

Unseen Histories

Was intelligence at this time seen as having a static value? Or did people have the capacity to improve themselves?

David Brydan

Early intelligence scientists disagreed over whether differences in intelligence were caused more by nature or nurture. But they tended to agree that intelligence was static in the sense that people's performance on intelligence tests stayed fairly consistent over their lifetimes.

This was an idea that was enthusiastically taken up by those who liked to suggest there was a hard division between the 'intelligent' and the 'unintelligent'. But I'm not sure how much purchase this idea gained across society as a whole; we seem to have very much maintained our popular faith in the development and improvability of our minds.

One of the most interesting findings to come from late twentieth century intelligence science was the so-called 'Flynn effect', which showed that, on average, intelligence has improved significantly over the last 100 years.

Unseen Histories

Can you tell us a little about the early intelligence tests? One that you outline in your book, given to a young woman called Margaret in 1942, seems very rudimentary.

David Brydan

Some of the early IQ tests contained questions that seem fairly odd today – questions about specific social norms or the beauty of women's faces, for example.

But these weren't necessarily the tests most people encountered. As soon as the first tests emerged a thriving publishing market for knock-offs, test-your-own-IQ books and self-help manuals sprang into existence, often with only a limited relationship to the research of intelligence scientists.

Schools, workplaces, and careers-advice services also started developing their own intelligence and aptitude tests. The test Margaret sat was one of these, and sounds like it was trying to test spatial reasoning and awareness.

Why that was deemed to be the most important ability for women wanting to join the armed forces in WW2 is anyone's guess.

Unseen Histories

World War Two demonstrated the terrifying consequences of dividing humans by biology. But while much of the early twentieth century enthusiasm for eugenics evaporated, interest in the concept of natural intelligence persisted through organisations like Mensa. Is that right?

David Brydan

The idea of intelligence was extremely popular with the eugenicists. Many of the early intelligence scientists wanted to find ways to improve the genetic 'quality' of the human race, including through mass sterilisation programmes.

The Nazis weren't that interested in the idea of intelligence, but killed hundreds of thousands of people in the T4 euthanasia programme, including people with intellectual disabilities who lives were deemed 'unworthy of life'.

The legacy of World War Two made arguments about the lower intelligence of certain races harder to make (although that didn't stop a lot of people trying). But the idea of intelligence retained its popularity.

Mensa exemplified this, growing from a tiny group of English eccentrics after the war to a global club with tens of thousands of members by the 1980s.

Unseen Histories

You point out early on that the current US president is addicted to ideas about IQ and ‘genius children’. Is this an echo of the mid-twentieth century culture that he grew up in?

David Brydan

To a certain extent, yes. Joe Biden – from the same generation – was also fond of throwing around the language of IQ, if in less offensive ways.

But there is a younger generation around Trump who seem similarly obsessed with the idea, including Elon Musk. That culture stems from a combination of Silicon Valley's hyper-meritocratic celebration of genius, and a strand of the neoliberal right which nurtured the idea of IQ after the controversies about race and intelligence in the US during the 1990s had made it largely taboo among liberals.

We've now returned to a world which sounds much like the 1920s, with Musk calling for 'high-IQ revolutionaries' to reform the government and Trump describing Somalis as 'low-IQ people'.

Unseen Histories

Your book included the intriguing story of an ‘idealistic’ Italian priest who founded a school for the gifted in the 1950s. Was this very much a story of its time?

David Brydan

To some extent it's a story of the whole twentieth century. The idea of separate education for 'gifted' children really began in the United States in the 1920s, led in part by intelligence scientists.

This spread around the world in the mid-twentieth century which is when the Italian priest, Don Calogero, opened his school in Sicily. But it continued to grow after that, and still forms part of many countries' education systems today.

It's always had an 'idealistic' element – aiming to identify highly intelligent children, including from working class or marginalised backgrounds, and giving them an education that will truly maximise their potential and benefit their societies. But this idealism was often combined with more elitist or exclusionary ideas, or represented a backlash against efforts to make education more egalitarian.

Unseen Histories

‘Some time around the 1990s’, you write, ‘a new set of ideas towards intelligence began to emerge.’ What were these and are they still present in our societies today?

David Brydan

The 1990s saw the start of a new obsession with the idea of a cognitive elite. This was an era when everyone was talking about globalisation and the knowledge economy, when deindustrialisation for the many sat side by side with a highly-educated global elite.

Many in this global elite were making fortunes in finance or consulting. They were part of a cult which I call the ‘neoliberal superman’ – the heroic, risk-taking entrepreneur or founder – which emerged from Silicon Valley.

We can argue that there has been a backlash against some of these ideas recently, underpinning the rising distrust of experts and the attack on ‘globalists’. But I think the celebration of ‘cognitive elites’ is still very much with us.

The idea of intelligence is still being used – as it has for over a century – to undermine the fight for equality.

Smart: A History of Intelligence

Icon, 5 February 2026
RRP: £20 | ISBN: 978-1804441763

We encounter the idea of intelligence everywhere in our modern lives. Parents are told that their children will grow up smart if they are made to listen to Mozart, play with the right toys, and eat the healthiest foods. Schools and universities plunge everyone into the ruthless world of testing and academic competition.

We are told repeatedly that some of the richest and most successful people in society – the tech pioneers, CEOs or financial wizards – are rich and successful precisely because they're so smart. And we now have to worry about the impact of artificial intelligence on our jobs, our societies, and the very survival of our species.

Intelligence, then, is an idea that infuses our world, and one that we think matters. This hasn't always been the case. Like all ideas, intelligence has a history.

Smart draws on the history of science, politics, and popular culture to uncover the stories of the people and projects that built the idea of modern intelligence – the men and women who created Mensa, the priest who built a village for gifted children in the mountains of Sicily, and the plan to boost the intelligence of the Venezuelan people by teaching them lateral thinking skills. These stories also reveal the dark side of intelligence, an idea that drove the modern counter-revolution against equality.

With thanks to Arabella Watkiss