Steve, the chorus of "Pig! Pig! Pig!" to Nozick's challenge highlights the most awful aspect of the hedonistic American take on happiness. This take says that happiness is entirely about how we feel, not at all about good commerce with the world. Our colleague and new Nobel laureate, Danny Kahneman, holds a sophisticated version of this take. Danny holds that an event (like a trip to Tuscany or a whole life) is some direct function of the number of pleasureful moments minus the painful moments. I think this is profoundly wrong.
The last words of Ludwig Wittgenstein give the lie to the hedonic account. He was by all accounts miserable. A collector of Wittgensteinobilia, I have never seen a photo of Wittgenstein smiling. (Actually one of my readers just last week sent me a photo of Wittgenstein "smiling." But it looks to me more like he has just sat on a sandwich.) Wittgenstein was melancholy, irascible, and scathingly critical of everyone around him and even more critical of himself. In a typical seminar held in his cold and barely furnished Cambridge rooms, he would pace the floor, muttering audibly, "Wittgenstein, Wittgenstein, what a terrible teacher you are." Yet his last words impeach all forms of happiology. Dying alone in a garret in Ithaca, N.Y., he said to his landlady, "Tell them it's been wonderful!" If we don't take Wittgenstein's judgment of a happy life seriously, whose can we take? Hence Authentic Happiness' delineation of three happy lives: the Pleasant, the Good, and the Meaningful.
I think, Steve, that we should be more careful about distinguishing "heritable" from "evolutionary" from "genetic" from "unchangeable." I believe that the Good Life may be heritable and evolved without being either genetic or unchangeable. (There are, by the way, no data at all on the heritability of flow and few on the heritability of the strengths). Take beauty, for example.
Evolution has certainly worked on beauty. Beauty is passed on from one generation to the next, as is the propensity to be attracted to it. Natural selection sees to it that sexually attractive people have higher reproductive success than ugly people. Beauty in turn is made up of simple traits like eye color, and eye color in turn has even simpler building blocks like a particular chain of DNA. But beauty, like automobiles, comes in many models, and its definition changes within limits over time and culture. There are many ways to be sexually attractive: many combinations of eye color, teeth, and hair will all be attractive, and more important, even more combinations will be ugly and so will be eliminated from the gene pool. If there are myriad kinds of beauty, then there are myriad molecular ways to construct "beauty," all of which get selected for. The upshot of this is that there is unlikely to be a genetics of beauty. There will not be "beauty genes," or there will be so many combinations of genes underlying beauty as to be scientifically unwieldy.
So, too, with the Good Life. There are at least 24 ubiquitous strengths, each of which might well be heritable. The Good Life consists in deploying different combinations of these strengths in work, love, and play. So any genetics of the Good Life will be scientifically unwieldy. Moreover, leading the Good Life is eminently changeable: It consists in identifying those strengths and using them more and more in the realms of life. So importantly, the Good Life may be heritable and evolved but highly malleable and not genetic. This is the main reason why the human genome project is likely to be a flop when it comes to complex traits.
And as for human nature and humane leadership, you and Bob and I still share the dream of a scientific understanding of this great question. Someday, we may hope.