Bookworm: Irrationality

Stuart Sutherland explains what drives our illogical decisions – and how to address this.

What’s the book's main premise?

From Aristotle’s claim that man is a “rational animal”, to Descartes’ famous statement “I think, therefore I am”, we have tended to think of ourselves as fundamentally rational creatures. However, we consistently make irrational decisions. And when people are in positions of power – doctors or law-makers, for example – the potential to do harm is immense.

In Irrationality, Stuart Sutherland takes a closer look at what’s driving our illogical decisions, unreasonable actions and irrational behaviour, looking both for the ‘why’ behind them and the ‘how’ we can become more logical in our decision-making. 

What's are Sutherland's credentials?

He was a renowned psychologist and writer who taught at Oxford University and the University of Sussex. Aside from Irrationality, he's best known for his book Breakdown, an account of his struggle with manic depression.

But what drives us to be irrational?

There are many reasons why we might behave irrationally, and key among them is “the availability error” – by which we ignore known facts and instead pay more attention to the information that makes the biggest impression on us, that which is most directly “available”.

This explains why anyone who has seen the film Jaws is more fearful of swimming in the sea than they are of their car ride to the beach, even though we are far more likely to die in a car accident than in a shark attack. This availability error also gives rise to other irrational behaviours such as the primacy error, where we form irrational beliefs based on a first impression.

And then there's halo effect, when we assume that someone with a noticeably “good” trait has other good traits as well. That’s why we tend to think that good-looking people are also intelligent.

What goes wrong when people aren’t rational?

When we rely on intuition rather than data and formal mathematical analysis, our ability to determine probabilities falters.

Think about doctors who rely on hunches, prime ministers who don’t listen to their cabinet ministers, banks that pay bonuses that encourage risky bets; they are all investing in discredited human intuition instead of facts and figures. In so doing, they may be putting lives and livelihoods at risk.

This problem is compounded by our tendency to be overconfident in our own gut feelings. For example, the 95% of British drivers who believe they are “better than average” drivers can’t all be right. And this may be further exacerbated still by our tendency to seek confirmation of our beliefs rather than contradictory evidence to test them, which would be the more rational thing to do.

Is there a good example of how we choose to behave irrationally?

With a firm eye on the absurdity of everyday life, Sutherland describes how we’d rather sit through a bad film or play in excruciating boredom than get up and leave, just because we've already paid.

The logical thing would be to leave, restricting our loss to the purely monetary. Yet our propensity for self-delusion leads us to believe that the second half of a rotten play might be better than the first. And so we waste our time as well as our money.

What lessons can I take from the book?

At the end of most chapters, Sutherland includes a handy round-up of key points, under the headline ‘Moral’.

For example, at the end of his chapter on obedience, the morals are:

1. Think before obeying.

2. Ask whether the command is justified.

3. Never volunteer to become a subject in the Psychological Laboratory at Yale (this one being  home to Stanley Milgram’s now-notorious obedience experiments from the 1960s, now rightfully considered shocking).

A key takeaway is that we can become more rational in our decision-making by trading intuition for statistical methods. Even totting up the items in a list of pros and cons can be useful.

What am I most likely to say after reading this book?

“Check the facts and figures.”

What am I least likely to say after reading this book?

“I have a hunch…”