Are Two Systems Better Than One?

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.