There is something immediately appealing about the idea that behavioural psychology can make people do things they otherwise would not. It is called "The Nudge". If, for example, a council labels its bins Recycling and Landfill, there will be less rubbish in the latter than if it was labelled General Refuse.
Unsurprisingly, the Government wants to apply such insights to public life. Trials altering the wording on official forms, it claims, have led to doctors paying £1m more in tax. But the idea that the billions lost through fraud can be reduced using the technique is less convincing.
Human beings are not always rational. Telling teenagers that their mother will hate a new video game, say, may make it seem more fun somehow. Fraud, however, is not subconscious. It is a crime that people deliberately set out to do. And something a good deal heftier than a nudge is required to deal with it.