Predictably Irrational, by Dan Ariely

In the past decade or so Behavioural Economics has become all the rage in both academic circles and among the general public. The financial crisis that started with the bursting of the sub-prime mortgage bubble in the US a couple of years ago has given behavioural economists a major boost.

The basic premise of behavioural economists is that humans are not necessarily rational when they make economic or financial decisions. One of the cornerstone assumptions of “traditional” economics is that we decide based on rational analysis of costs and benefits and seek to maximise our financial gains. It turns out this is not the case and many of our decisions are driven by “irrational” factors that defy the premises of traditional economics.

Professor Dan Ariely is another ex-Israeli scientist that has popularised Behavioral Economics with his book Predictably Irrational. Using relatively simple experiments he shows that many of our decisions are influenced by irrational factors, but more importantly, that this irrational behaviour is, in many cases, predictable. In other words, contrary to popular belief (at least in the last 300 or so years of the “scientific era”), humans are inherently irrational.

Here are a few examples:

• People will feel better taking a medicine that costs 10 times as much as another, identical, medicine.
• When faced with a free product, we will likely “buy” it even if they don’t need it.
• Sexual arousal will lead people to change their behaviour and perform deeds they deem immoral.
• We will think food or drink are better if they are presented in a more glamorous setting.

Ariely’s book is highly entertaining and provides some delightful nuggets of truth about ourselves. But I didn’t find many of his “discoveries” surprising. It is true that we like to see ourselves as rational machines, but most of our life experiences clearly demonstrate this is not the case. Blind belief in a purely rational brain is, well, irrational. The work of Nobel prize winner Daniel Kahenman (with his partner Amos Tversky), around how people decide between alternatives involving risk, has been known for many years. Ariely’s achievement is mainly in popularising the subject and presenting it in a way that most people can understand.