Dual-process theories hold that there are two distinct processing modes available for many cognitive tasks: one that is fast, automatic and non-conscious, and another that is slow, controlled and conscious. Typically, cognitive biases are attributed to type 1 processes, which are held to be heuristic or associative, and logical responses to type 2 processes, which are characterised as rule-based or analytical. Dual-system theories go further and assign these two types of process to two separate reasoning systems, System 1 and System (...) 2 – a view sometimes described as ‘the two minds hypothesis’. It is often claimed that System 2 is uniquely human and the source of our capacity for abstract and hypothetical thinking. This study is an introduction to dual-process and dual-system theories. It looks at some precursors, surveys key work in the fields of learning, reasoning, social cognition and decision making, and identifies some recent trends and philosophical applications. (shrink)