When the Americans declared independence over two centuries ago they also declared the pursuit of happiness, along with life and liberty, to be an unalienable right. Until recently, however, that has not featured as an explicit goal for governments. Rather, they have concentrated on objective measures of economic and social improvement, such as living standards. That is now changing. In Britain, for example, the coalition led by David Cameron is starting to gauge quality of life by asking people how happy or anxious they have been feeling, how satisfied they are with their lives and how worthwhile are the things they do.

Will such new measures of well-being be any more meaningful than traditional indicators? Is the new focus on quality of life a welcome recognition that governments can and should promote happiness, or will it open the door to meddlesome states that intrude into people’s personal lives?