My PhD project analyzes some recent developments in the ‘rationality debate’, which originated as a reaction to the body of research that has followed Kahneman and Tversky’s work within the Heuristics-and-Biases project. Empirical evidence suggested that people are prone to widespread and systematic reasoning errors, and pessimistic views of human rationality have been quite popular in the psychological literature. However, this picture has also attracted fierce criticisms, and several researchers have recently questioned pessimistic assessments of human rationality by emphasizing the central importance of evolutionary considerations in our understanding of rationality.
In a paper I recently published in Philosophy of the Social Sciences I present some steps already taken in my project. In particular, I critically discuss some research that has come together under the umbrella term of “adaptive rationality” (AR) (e.g., Todd and Gigerenzer 2012). According to this view, people should not be assessed against norms of logic, probability theory, and decision theory, but rather against the goals they entertain. Moreover, the conclusion that people are irrational is seen as unsupported: people are often remarkably successful once assessed against their goals and given the cognitive and external constraints imposed by the environment.
I suggest that these theorists are right in arguing for a conceptual revolution in the study of human rationality. To show this, I start by considering the ways in which decision scientists tend to justify traditional norms of rationality. A prominent justification is pragmatic: it is commonly argued that if people violate such norms, they will incur costs. But these links are open to empirical testing. As Baron puts it:
'If it should turn out […] that carefully violating the laws of logic at every turn leads to eternal happiness, then it is these violations that should be called rational' (Baron 2000: 53).
AR theorists take this possibility seriously. Their research shows that behaviour that violates norms of rationality can be successful once measured against epistemic and individual goals. AR theorists seem right in claiming that, given the pragmatic premises, we have no grounds for considering those behaviours as irrational.
But where does this lead us? According to AR theorists, we should think of human cognition as adaptive and successful. This is problematic, though. In fact, empirical evidence suggests that people can be quite unsuccessful at achieving their goals. To take an example, let’s go back to the quote from Baron. Are people really good at predicting what will make them happy? In recent years decision scientists have started to directly study contexts when decisions succeed and fail to maximize happiness. An important result seems to be that people often fail to make choices that maximize their happiness. By looking at this as well as other examples, I try to show that in some important contexts people are, after all, ‘adaptively irrational’.