Link Search Menu Expand Document


These are the lecture notes for a course called Are Two Systems Better Than One? at the University of Milan by Corrado Sinigaglia and Steve Butterfill.

Two systems theories of reasoning are well-known and widely discussed. However less attention has been paid to two systems (or dual process) theories in other domains. What are two systems theories, and in which domains are they defensible? In this course we will consider the view that two systems can be distinguished in almost any domain, including number, colour, object, ethical and social cognition. This view, if correct, requires us to understand why in so many cases two systems are better than one.

We will consider a range of theoretical issues and methods which are important for understanding claims about systems and processes. These include automaticity, information encapsulation, processes dissociation, signature limits and interface problems.

The overall questions for these lectures are:

  • In which domains is there substantial evidence for a two systems theory?

  • How are the two systems distinguished?

  • Why are there two systems?

  • When, if ever, are two systems better than one?

  • How, if at all, do the two systems interact? What are the barriers to interaction between them?

  • What, if any, kind of unity is there across domains?