This article in the Guardian about the cult of measuring "happiness" reminded me of something that Karl Popper wrote in 1948:
"Do not aim at establishing happiness by political means. Rather aim at the elimination of concrete miseries. Or, in more practical terms: fight for the elimination of poverty by direct means - for example, by making sure that everybody has a minimum income. Or fight against epidemics and disease by erecting hospitals and schools of medicine. Fight illiteracy as you fight criminality. But do all this by direct means."
The intuition is simple and straightforward. The things that make the members of a political community happy are diverse, so whose happiness are we going to prioritize? The things that create misery tend to be common to everyone. There is an asymmetry, ergo public policy is unlikely to have much impact if it aims at promoting happiness. It might be more successful and generate political support if it tackles miseries that everyone has some risk of experiencing.
The writers of the US Declaration of Independence seem to have spotted this: life liberty and the pursuit of happiness. Strange that neither New Labour nor the Tory/LibDems seem to have noticed. Or maybe they have. Vague policy goals like social mobility and happiness are perfect if you want to do nothing or despair of doing anything about real human misery.