RATIONALITY A MUSCLE THAT NEEDS CONSTANT FLEXING

Ithe 1964 film My Fair Lady after Colonel Pickering has secured the help of an old friend to pull strings at the Home Office (plus ça change) in the hope of finding the absconded Eliza Doolittle, Professor Higgins snaps: “Why is thinking something women never do?/ And why is logic never even tried?/ Straightening up their hair is all they ever do./ Why don’t they straighten up the mess that’s inside?"

Today the sex and gender wars are more nuanced than that, at least in public, but the charge of stupidity and unthinkingness has found many other targets: antivaxxers, Brexiteers, conspiracy theorists, climate change activists on the M25, and so on.

Unlike Henry Higgins’s pointed criticism, Steven Pinker, a Harvard professor of cognitive psychology and seasoned populariser of subjects far beyond, sees a mess inside every one of us. He takes an evolutionary perspective to argue that the mess is getting worse; humans aren’t used to the volume, immediacy and pace of information that fuels our connected lives. In essence, we fail woefully to be rational. But do we really want to fare better? Rational personalities can seem dull and inhibited. What is rationality? Pinker settles on the definition that it’s “the ability to use knowledge to attain goals”, or to work with the truth to get where we want. But assuming our values are well-intentioned, people can be “goaded into applying their best habits of thinking” to avoid the “siren songs that lure us from good decisions”. Rationality is a muscle of sorts, or rather a collaborative group of muscles. Pinker has the noble aim of making cognitive exercise as aspirational and appealing as working on your six-pack.

There’s a skill in identifying tempting wrong answers to a question that lead you to the right one. Imagine buying a smartphone and a case, costing $110 in total. “The phone costs $100 more than the case. How much does the case cost?” You know that if the answer were $10, Pinker wouldn’t be asking the question. It’s easier to resist the round numbers ($10) when the scenario is packaged as a test, and you want the dopamine hit of getting it right ($5). But when these scenarios are woven through our daily lives — in sales pitches, investment opportunities, the six o’clock news — with less predictable rewards, our brains are rash and vulnerable.

Pinker is indebted to the psychologist Daniel Kahneman, who wrote the 2011 smash-hit Thinking, Fast and Slow, that describes how humans are crippled by cognitive biases. We tend to think linearly rather than exponentially, underestimating the value of saving money over the long haul or the rapid spread of a virus. If we have examples to hand, we overestimate both risks and benefits. After hearing about a drowning accident, we’re more likely to fret about our next wild swim.

It’s very hard to put probabilities into words. Data, while much more precise, and therefore essential to public communication, can also be highly misleading. Pinker’s discussion of Bayesian reasoning, like much of the book, is fascinating. His example emphasises why rationing medical tests is often a public good, particularly for hypochondriacs. Rationality doesn’t only outline our flaws, but also suggests ways to minimise them. Deriving and storing knowledge in communities — colleges, think-tanks, the media — prevents the biases of individuals running riot. The randomised controlled trial, for example, is “an impeccable way to cut these knots” of irrationality, Pinker argues, because the randomising, doubleblind design and the intervention vs control arms of the experiment minimise human meddling.

Still, these collective efforts need to win our confidence. I’m a doctor, but my understanding of how the Covid vaccines work is superficial. I took my vaccine not because I reasoned my way there from first principles: I trusted, and was led. Pinker advises we choose our company well, as it feels better and safer to make decisions that align with those around us. For me that’s a tribe of compassionate nerds, not people who watch Fox News. Vaccine uptake is higher in the UK than the US not because we’re more rational. We have a health system with many vulnerabilities, but corruption and profiteering are not chief among them. Trust is a resource. But at any time, the public may no longer care to trust if they suspect that institutions no longer care for them.

Pinker, as his book would predict, deviates from his own standards of rationality when discussing issues close to his heart. He makes straw men out of the “cultural anthropologists” and “literary scholars” who “avow that the truths of science are merely the narratives of one culture” yet “have their child’s infection treated with antibiotics”. Pinker demonstrates the availability heuristic when he states that “universities have turned themselves into laughing stocks for their assaults on common sense” and are at the “forefront of finding ways to suppress opinions”.

The forefront? Really? He overstates the problem by the number of examples he can produce, prompted by his own stakes in this debate. A rational life also requires “epistemic humility”, a humility which Pinker is not always willing to extend to the social sciences and humanities. As a result, he oversimplifies the current challenges we face about knowledge — the suspicion of expertise, the bias in our data collection — which these academic disciplines work hard to explain and unmask.