Freakonomics has an interesting post on whether the old adage that ignorance is bliss is true. The post suggests evidence that the opposite is true for a simple analysis in the U.S., and links to a study that suggests there is no effect across countries once they control for basic income. But I wonder.
My interpretation of the "ignorance is bliss" philosophy is not just that you're ignorant, but that also you don't know that you're ignorant. Once you know how much you don't know (or, conversely, how much you don't control), unhappiness will undoubtedly follow.
Few people these days, rich or poor, educated or not, think that they know much of whats going on in the world. Perhaps these measures of unhappiness are really picking up how much as a species we think we know.
Or maybe there is a strong correlation with religious fundamentalism, which purports to give us the answers and argues no other answers are needed (or even that all others are evil). So, is it then science, or any critical exercise aimed at religious explanations of creation, which makes us unhappy?
PhD Comics from years ago, on how graduate school makes you dumber, has always struck me as right on the mark in this debate. Once you realize how much you really don't know, you become dumber, and there's no going back.