Behavioural science explains Iran debate

OF all the findings in behavioural science, the most significant may be "loss aversion", the idea that people dislike losses a lot more than they like equivalent gains.

Loss aversion can create big trouble for businesses and investors. And it can badly confuse political debate - as it seems to be doing in the current discussions of the nuclear deal with Iran. (Disclosure: My wife, Samantha Power, is the US ambassador to the United Nations.)

Here is a simple demonstration of the power of loss aversion: When a convenience store offers shoppers a five US cent bonus for bringing their own bags, they still don't bother. But when the store charges five US cents for each plastic bag it distributes, shoppers use a lot fewer of them. The prospect of loss concentrates the mind.