Why Do Humans Reason? Arguments for an Argumentative Theory

Hugo Mercier and Dan Sperber make the case:

Reasoning is generally seen as a mean to improve knowledge and make better decisions. Much evidence, however, shows that reasoning often leads to epistemic distortions and poor decisions. This suggests rethinking the function of reasoning. Our hypothesis is that the function of reasoning is argumentative. It is to devise and evaluate arguments intended to persuade. Reasoning so conceived is adaptive given human exceptional dependence on communication and vulnerability to misinformation. A wide range of evidence in the psychology or reasoning and decision making can be reinterpreted and better explained in the light of this hypothesis. Poor performance in standard reasoning tasks is explained by the lack of argumentative context. When the same problems are placed in a proper argumentative setting, people turn out to be skilled arguers. Skilled arguers, however, are not after the truth but after arguments supporting their views. This explains the notorious confirmation bias. This bias is apparent not only when people are actually arguing but also when they are reasoning proactively with the perspective of having to defend their opinions. Reasoning so motivated can distort evaluations and attitudes and allow the persistence of erroneous beliefs. Proactively used reasoning also favors decisions that are easy to justify but not necessarily better. In all of these instances traditionally described as failures or flaws, reasoning does exactly what can be expected of an argumentative device: look for arguments that support a given conclusion, and favor conclusions in support of which arguments can be found.

The claims the paper presents are not as disheartening as the abstract may suggest:

[T]he argumentative theory of reasoning..maintains that there is an asymmetry between the production of arguments, which involves an intrinsic bias in favour of the opinions or decisions of the arguer whatever their soundness, and the evaluation of arguments, which aims at differentiating good arguments from bad ones and thereby genuine information from misinformation. This asymmetry is often obscured in a debate situation (or in a situation where a debate is anticipated). People who have an opinion to defend don't really evaluate the arguments of their interlocutors in search for genuine information but rather consider them from the start as counter-arguments to be rebuked. Still, as shown by the evidence reviewed in section 2, people are good at assessing arguments, and are quite able to do so in an unbiased way, provided they don't have a particular axe to grind. In group reasoning experiments where participants share an interest in discovering the right answer, it has been shown that truth wins.