Read carefully, and think. A smartphone and case, combined, cost £110. The phone costs £100 more than the case. How much is the case?

If you answered £10, you are, like most people: wrong. The answer, of course, is £5 (£105 is £100 more than £5, and £5 + £105 = £110).

This is one of many simple logic questions from Rationality, the latest book by Steven Pinker, the anti-woke Harvard cognitive psychologist famous for his bestsellers on language (The Language Instinct), human nature (The Blank Slate), why the world is getting less, not more, violent (The Better Angels of Our Nature), among many others.

Of a set of three such questions, five out of six university students got at least one wrong, and one in three got them all wrong. Even maths students from the Massachusetts Institute of Technology (MIT) averaged only two out of three correct, falling into the trap identified in Pinker’s book as the lure of irrelevant ‘superficial features’.

I confess to Pinker that I was one of the dunderheads who was wrong on all three questions after making a snap decision. He laughs with kindness.

He is Zooming me from Berkeley, California, where he is spending a sabbatical year with his step-daughters and their small children (as opposed to the University of California, Berkeley, a place considered more extreme even than ‘the Republic of Cambridge’, Harvard’s home town). He is there with his wife, the philosopher Rebecca Goldstein, author of a superb little book on Spinoza - they’re a brainy pair.

People with thinking as run-of-the-mill faulty as mine are the target audience of his new 12-part Radio 4 series, Think with Pinker and sees him tackle problems of the modern world with theoretical experts and real-life practitioners.

The episode on climate change features Bill Gates on how the market can save the world, and mathematician Hannah Fry on game theory’s application to our environmental behaviour. Other episodes explore Bayesian reasoning in medicine and the application of rationality to law and governance – ‘how do you get people to take advantage of government benefits or wear masks?’ One sees Ellen Peters, author of a book on numeracy, explain why poor quantitative reasoning leads to less money and poorer health.

Both the radio series and Rationality – like all of Pinker’s work – are a paean to human potential. Though his detractors insist he offers a typically Western male take on what constitutes truth and reason, what Pinker really trades in are energising explanations as to why we think the way we do.

‘I wanted to make people aware of their own biases and fallacies, and where they come from, and to try to explain them as a psychologist,’ he tells me of the latest project. ‘I was not content to say that the human brain is this buggy contraption, just a blender machine. I was very clear that human rationality is a genuine phenomenon.’

As a species, we are ‘flagrantly rational... we have transformed the planet, we’ve doubled our life span, we’ve decimated infant mortality and disease and famine, we’ve reached the moon, discovered the origins of the universe’.

The challenge is to understand why and how this can ‘coexist with the obvious nonsense that our species is also capable of’ – in this list Pinker includes ‘trolling, disinformation, the New Age receptivity to paranormal woo woo, to astrology, crystal healing, the spread of preposterous fake news and conspiracy theories’.

One of Pinker’s most pungent takeaways is that intuition, or ‘gut feeling’, is very often wrong. It was this, for instance, that led me and so many others to the wrong answer on the smartphone problem.

‘In particular, when it comes to human expert judgment,’ says Pinker, ‘one of the strongest findings in psychology is that you pitch the expert against even a simple formula – we’re not even talking about AI algorithms – a formula does better than a judge. Human intuition is easily fooled.’

The book, and the radio series, are packed with examples of just the kind of ‘intuitive’ thinking that backfires: the discounting of the future in favour of the present; that winning is better than being right; that things that feel remote don’t really exist, and so on.

So is our treasured gut feeling really useless? Not always, especially when it comes to sizing someone up. ‘Even if you can’t verbally articulate what you like about them,’ you may be ‘amalgamating tens or maybe hundreds or thousands of cues, bits of information, adding them up’, he says.

And sometimes, irrationality is the best course – in relationships, for example, it is knowing you’re loved for your ‘indescribable unique quirks’, rather than a box-ticking exercise, that persuades people to commit.

But in general, we can and should improve our thinking by weaning ourselves off gut feelings. Reading his book, says Pinker, is a good start and when I protest that it is actually quite challenging, he smiles patiently but not without a steely gleam in his eye: ‘The reader should be prepared to put in some mental effort. That’s their part of the bargain. My part of the bargain if they put in the effort, I’ll have done the work so that it will be understandable.’

For some, a second reading will be needed, but it’s true: Pinker writes like a dream, with Orwellian clarity, and this makes puzzling over his explanations fun. But I wonder what it’s like, in everyday life, being so aware of the mechanisms behind the way humans speak, think and act. Does it cause Pinker paralysis?

‘Sometimes. I’m agonising over a decision as we speak. I’m not impulsive, I give decisions a lot of thought and it may be to my disadvantage in holding, say, executive positions, which I have rarely held in my career. The number of decisions would paralyse me, unlike a good friend of mine who has held a number of these positions, and he said, it’s not the way I think – if a decision is really difficult that means that both alternatives have advantages, it doesn’t matter which one you choose, because both are good, so I don’t spend that much time on decisions. And I thought, that’s why he’s a department chairman and institute president and I’m not.’

Being a rational thinker also translates into a healthy physical regime: having grown up in an era when ‘men would drop like flies’ from heart attacks, Pinker has ‘exercised regularly for 40 years’ - he’s a particularly avid cyclist in his summer home of Cape Cod. He sticks to a low-fat diet, has never smoked and weighs himself every morning.

Finally, I ask whether rationality can be used in solving life’s trickiest dilemmas, those that don’t have right and wrong answers, such as whether to have a child. Pinker says yes. ‘It’s going to sound really nerdy,’ but if you were so inclined, there is ‘in theory’ a way to calculate even the child question: ‘You multiply the risk by the utility, that is the pleasure or pain, you add them up, each of the two choices, and you choose the choice with the higher sum.’

If nerdiness is the essence of the Pinkerian universe, then I want more of 
it, feeling clearly, as we end the call, 
that harnessing reason is not just useful 
in all kinds of ways both personal and universal, but a wondrous property of 
being human.

The Daily Telegraph

Read more