David Wootton in Lapham’s Quarterly:
We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty, and the pursuit of Happiness.
—The Declaration of Independence
These words, from Thomas Jefferson’s Declaration of Independence, are so familiar that it is easy to assume their meaning is obvious. The puzzle lies in the assertion that we have a right to pursue happiness. John Locke, in his Two Treatises of 1690, said we are all created equal and have inalienable rights, including those to life and liberty. But for Locke the third crucial right was the right to property. In Locke’s Essay Concerning Human Understanding, also published in 1690, he wrote about the pursuit of happiness, but it follows from his account there that there can be no right to pursue happiness because we will pursue happiness come what may. The pursuit of happiness is a law of human nature (of what we now call psychology), just as gravity is a law of physics. A right to pursue happiness is no more necessary than a right for water to run downhill.
Jefferson meant, I think, that we have a right to certain preconditions that will allow us to pursue happiness: freedom of speech, so we can speak our minds and learn from others; a career open to talents, so our efforts may be rewarded; freedom of worship, so we may find our way to heaven; and a free market, so we can pursue prosperity. Read this way, Jefferson’s right to the pursuit of happiness is an elaboration of the right to liberty. Liberty means not only freedom from coercion, or freedom under the law—or even the right to participate in politics—it is also a right to live in a free community in which individuals themselves decide how they want to achieve happiness. The “public happiness” to which Jefferson aspired can therefore be attained, since public happiness requires liberty in this expanded sense.
Jefferson was well aware that being free to pursue happiness does not mean that everyone will be happy. And yet we trick ourselves into thinking we know what is needed to be happy: a promotion, a new car, a vacation, a good-looking partner. We believe this even though we know there are plenty of people with good jobs, new cars, vacations, and attractive partners, and many of them are miserable.
More here.