Dual system theories demolished

Posted on July 14, 2010


The most thorough critique that one can offer for any particular position should, it seems to me, contain two elements. The first should be the standard argument showing why it is that the position under attack is fallacious. The second, but often forgotten, element is an explanation for why it is that some people, often very intelligent people, should come to believe that particular falsehood. It is a pleasure, therefore, to see a paper which critiques dual system accounts, which I have been very sceptical about for a number of years, containing both of these elements. I am talking about “Two is not always better than one” by Gideon Keren and Yaacov Schul, published in Pespectives on Psychological Science last year:

Over the past two decades, there has been an upsurge in theoretical frameworks alluding to the existence of two different processing systems that supposedly operate according to different rules. This article critically examines the scientific advance offered by these theories (in particular advances in the domains of reasoning, decision making, and social cognition) and questions their theoretical coherence as well as the evidence for their existence. We scrutinize the conceptual underpinnings of two-system models and explicate the assumptions underlying these models to see whether they are reasonable. We also evaluate the empirical paradigms used to validate two-system models and ponder about their explanatory strength and predictive power. Given the popularity of these models, we discuss the appeal of two-system theories and suggest potential reasons for their prevalence. We comment on the potential costs associated with these models and allude to the desired nature of potential alternatives. We conclude that two-system models currently provide little scientific advance, and we encourage researchers to adopt more rigorous conceptual definitions and employ more stringent criteria for testing the empirical evidence in support for two-system theories.

I think the article is so thorough in its critique that there is little to be said on the issue from the psychology side – I’ll definitely be using the article in my book. Interestingly, having just read an article by Jonathan Evans in In Two Minds where he walks back most of the claims that dual system proponents like him have been making, it seems that the whole debate is moving in this direction. About time. I am glad that my own critique of dual system accounts comes much more from a historical and philosophical direction as, otherwise, it seems to me that I would now have very little to write on the issue.