I've been dipping into the literature on the measurement of happiness, and the most stunning thing about happiness is that it is so incredibly robust. It seems that there is almost nothing one can do to significantly and permanently alter one's natural temperamental disposition to happiness. Most people in most places are pretty happy. Income means very little. People who suffer horrifying disfigurements and disabilities usually bounce right back to their happiness “set-point.” The Minnesota twins studies show that hedonic tone is to a large degree genetic. It seems that even people in prison aren't a whole lot less happy than people not in prison. Freedom and democracy mean something, but not that much. If you're on good terms with your family, have close friends and meaningful work, you're probably doing about as well as you're going to do.
All this implies that any form of happiness-consequentialism is pretty much useless as anything more than a very brute standard of evaluation. I have yet to fully process what this really means. (It does mean that the Objectivist subjective-happiness-as-barometer-of objective-life-success view is plain false.) I do think this pushes me to a more Scanlonian view according to which our reasons for action are not even close to exhausted by considerations of “well-being.” If being more free, more healthy, and so forth do not cash out in terms of happiness, then so much the worse for cashing out value in terms of happiness.
Additionally, I think the methodological implications of the happiness research on measurement problems in economics have yet to be digested. Consider the concluding paragraph of Krugman's excellent essay “Viagra and the Wealth of Nations“:
In other words, as soon as you try to think seriously about how to measure Viagra's effect on the nation's wealth, you realize what a dubious enterprise such comparisons are. I have nothing against calculating real G.D.P. as accurately as possible; we need that number for all kinds of purposes. But the rather vulgar case of Viagra reminds us that, in the end, economics is not about wealth — it's about the pursuit of happiness.
Krugman seems to be saying that “problem of Viagra” is not simply a problem for calculating the effects new innovations have on material wealth, but a problem for determining the effects of innovation on happiness (which is what wealth really amounts to). But if we take the happiness research seriously, almost nothing has much effect on anyone's long-term happiness. So if we are to say what makes it better to have Viagra than to not have Viagra (or whatever), then we're going to have to say something about our reasons to value more possibilities, more choices, and enhanced abilities. But what we have to say is not going to be much about happiness. That is to say, “wealth” isn't a measure of happiness, either. My intuition about what wealth is: a garden of forking paths leading to multitudes of possible lives.