Friday, November 30, 2012

Nagel on Haidt 1: Group Selection

Thomas Nagel reviews Jonathan Haidt’s The Righteous Mind: Why Good People Are Divided by Politics and Religion (along with Dignity: Its History and Meaning by Michael Rosen) in The New York Review of Books.  Here is Nagel’s summary of Haidt’s theory:
Haidt’s empirical theory, which he calls “moral foundations theory,” is an example of evolutionary psychology. It is the hypothesis that a set of innate “modules” of moral response were fixed in humans by natural selection, and that these responses, further shaped by cultural evolution in various more specific forms and combinations, underlie the widely divergent moralities that we observe not only across the globe but within pluralistic cultures like that of the United States…
Haidt distinguishes six basic types of moral response, which he likens to distinct taste receptors, so that different moralities are like different cuisines in the use they make of these responses. Each type manifests itself through intuitive emotional reactions, positive and negative, to a specific value or its violation, so he gives them double-barreled names: care/harm, liberty/oppression, fairness/cheating, loyalty/betrayal, authority/subversion, and sanctity/degradation. Haidt believes that all these responses developed in their basic innate form because they suppress or regulate self-interest and make cooperation possible among people who are not close relatives.
I am cutting and pasting here to isolate the following topic. 
Specifically, Haidt argues that group selection—selection for genetic traits whose presence benefited social groups of early humans in competition with other groups, rather than individual selection for traits that enhanced the reproductive success of individuals in competition with other individuals—is responsible for the main moral dispositions. The existence of group selection is a highly contentious issue in evolutionary biology. Haidt defends it in this case on the ground that moral norms can include cheap enforcement mechanisms, such as forms of group pressure, that cancel the genetic advantage for any individual of trying to benefit from the group’s success while not following the norms—free riding, in other words.
Individual natural selection can explain psychological traits that benefit the individual and his close kin; but group selection, he argues, is needed to explain those traits that benefit individuals only by sustaining norms that preserve the cohesion of the group.
As Nagel observes, group selection is a very controversial issue in Darwinian Theory.  As the argument is frequently put, any altruistic trait that benefitted the growth of a group as a whole without conferring a reproductive benefit on the individual altruist against other members of the group would quickly go out of business.  As the group grows relative to other groups, the portion of altruists would shrink and disappear.  Thus group selection cannot work. 
One way to make group selection work would be for groups to continually break up and reform.  If the group-benefit trait works to increase the size of the group faster than individual selection within the group works against the altruists and groups break up and reassemble faster than the latter can complete its work, altruists might be sustained in the general population. 
Another way to make group selection work would be for the altruists to have a way of purging non-altruists from the group.  Haidt argues that group selection is necessary to explain the evolution of moral instincts.  I would point out that the obverse is equally true.  Moral instincts are necessary to make group selection possible. 
Whether group selection is a common feature of creatures other than human beings is to be sure difficult to demonstrate.  That natural selection favors human beings who can cooperate with one another much more effectively than other social animals because the moral instincts allow such persons to trust one another seems very likely.  The moral instincts are clearly not limited either to direct self-interest or to a preference for genetic relatives.  Young children will readily cooperate with individuals who they have just met, coming to their aid or engaging them in games.  Once cooperation has begun, the child will expect the partner to keep playing the game. 
I think Haidt is right to believe that group selection is necessary for the moral instincts to evolve.  I think also that something like moral instincts are necessary for group selection to work among social animals.  


  1. I'm not sure how these "moral instincts" arise under group selection. It would seem to require tremendous selection pressure, and it is not likely that the groups would differ significantly enough to make that much difference. It makes more sense that they arose initially under kin selection in a few isolated groups of related individuals. After these "moral instincts" were established in this small population, then it makes sense that group selection might have an effect in the "moral" population outcompeting other less "moral" groups.

  2. Donald: selection pressure involves time in its function. Very small reproductive advantages can favor traits given enough generations.

    It is also probable that the traits that group selection might work on would predate the emergence of the human species. Chimpanzees are poor cooperators compared to human children, but they do cooperate even with unrelated individuals.

    Contrary to what you argue, it seems to me that a group with even a slightly enhanced cooperative instinct might be much more successful than groups without the same.

    At any rate, the human capacity for cooperation is so far off the scale of other primates that it is likely a case of runaway selection, similar to the peacock's tail.