Did the human capacity to reason evolve as a mechanism to acquire truth? Or was it only in the service of winning arguments?

This is the question at the center of an article by Hugo Mercier and Dan Sperber in The Journal of Behavioral and Brain Sciences. Described by the New York Times, the article observes that language and reason have little to do with “truth and accuracy.” Quoting Mercier:

Reasoning doesn’t have this function of helping us to get better beliefs and make better decisions. It was a purely social phenomenon. It evolved to help us convince others and to be careful when others try to convince us.

The position of Mercier and Sperber would appear to provide an evolutionary explanation for all manner of rhetorical devices and tendencies. Individuals, for example, have a tendency to ignore data that does not support their case. This phenomenon is called confirmation bias. In a sense, reason isn’t an instrument by which to acquire truth. Instead, it’s perhaps more ambiguous. Reason is a means by which to convince others, change their minds. Reason is coercive.

Mercier and Sperber’s argument has inflamed some elements of the academic community. Darcia Narvaez, an associate professor of psychology at the University of Notre Dame diminished the theory as a moment of academic fashion:

[it] fits into evolutionary psychology mainstream thinking at the moment, that everything we do is motivated by selfishness and manipulating others, which is, in my view, crazy.

Others have remarked that Mercier and Sperber’s argument is in fact an example of the wisdom of crowds or the aim of deliberative democracy, described by Rawls and Habermas. Jonathan Haidt, a professor at UVA quoted by the Times, suggested as much:

Their work is important and points to some ways that the limits of reason can be overcome by putting people together in the right way, in particular to challenge people’s confirmation biases.

Mercier and Sperber appear to be heading in this direction, as well. Their article points to the advantages of group dynamics in the development of strong arguments. The group, after all, is equipped to present and vet many perspectives in rapid succession. The group could conceivably pick apart instances of confirmation bias and illuminate flaws in reasoning. According to Mercier and Sperber,

At least in some cultural contexts, this results in a kind of arms race towards greater sophistication in the production and evaluation of arguments. When people are motivated to reason, they do a better job at accepting only sound arguments, which is quite generally to their advantage.

Yes. Reason may be coercive, but Mercier and Sperber seem to be saying that with enough reason, enough speech, the group should arrive at a better outcome. Indeed, it’s reminiscent of the logic underpinning the metaphor of the marketplace of ideas – that more speech and more argument might spawn better speech. Justice Holmes, who coined the phrase in 1919, would be proud.

The marketplace metaphor, however, is flawed. As we’ve seen at other times, through the views of Ronald Coase, Justice Stevens, and others, an efficient market in speech does not equate to some Spenserian concept of survival of the fittest.  Indeed, Mercier rather off-handedly observed, “It doesn’t seem to work in the U.S.” Which leaves us with a question, just what is this metaphor we call the marketplace of ideas? Is the mere presence of a group itself sufficient to present and vet a variety of arguments? How do economic resources distort the marketplace of ideas?