46 | New Scientist | 11 December 2021

Features Interview

How to be

more rational

To explain the paradox of why a smart species

embraces so much codswallop, we need

to rethink rationality, as Steven Pinker

tells New Scientist

H

UMANITY faces some huge

challenges, from the coronavirus

pandemic and climate change to

fundamentalism, inequality, racism and

war. Now, more than ever, we need to think

clearly to come up with solutions. But instead,

conspiracy theories abound, fake news is

in vogue and belief in the paranormal is as

strong as ever. It seems that we are suffering

from a collective failure of rationality.

Steven Pinker doesn’t buy into this

disheartening conclusion. In his new book,

Rationality: What it is, why it seems scarce,

why it matters, the Harvard University

psychologist challenges the orthodoxy

that sees Homo sapiens as a species stuck

in the past, with an ancient brain fuelled

by biases, fallacies and illusions, incapable

of understanding the complexities of the

modern world.

History, he argues, refutes that. After all,

humans have built civilisations, discovered

the laws of nature, vanquished diseases and

identified the building blocks of rationality

itself. Ours isn’t an innately irrational species,

says Pinker. However, we don’t embrace our

rational side as much as we might. With more

insight into the human mind, we can learn

to change that – and master an underused

resource that will help us tackle the challenges

of the 21st century and beyond.

New Scientist: What do you mean by rationality?

Steven Pinker: I define it as the use of

knowledge to attain goals. There is not one

single tool of rationality – it depends what

you’re after. If you’re seeking to derive new

true statements from existing ones, then

logic is your tool. If you want to assess your

degree of belief in a hypothesis based on

evidence, then Bayesian reasoning. If you

want to figure out what’s the rational thing

to do when the outcome depends on what

other rational people do, game theory.

Those tools don’t seem to come naturally

to people, yet you reject the idea that human

cognition is a heffalump trap of biases and

delusions that are a legacy of our evolution. Why?

Yeah, I don’t think it’s quite right. Although

there’s no question we do have outbursts of

irrationality – and they are all too plentiful –

I’m not ready to write off our species as

irrational. We can all be rational when it comes

to our immediate surroundings and outcomes

that affect our lives. And if you’re upset about

some outbursts of irrationality, don’t blame

hunter-gatherers. I begin the book with a

description of how the San people of the

Kalahari desert deploy rationality to engage

in pursuit hunting, where they’ve got to figure

out where the antelope may have run based

on some fragmentary tracks on the ground.

They engage in some pretty sophisticated

inference. They wouldn’t survive if they didn’t.

All of us command some aspect of

rationality. In our everyday lives we package

it with subject-matter knowledge in particular

areas – bringing up the kids, holding down

a job, getting food in the fridge. What we

don’t wield are tools that can be applied to

any subject matter: calculating probability,

distinguishing correlation from causation,

Bayesian reasoning, statistical decision

theory. Those come less naturally to us.

And when it comes to issues that are larger

than our day-to-day physical existence,

people don’t necessarily hew to the mindset