There are many different ways of studying human judgement. Individual researchers into the subject tend to focus on just one or two of them and to neglect others. As a result, a number of different literatures have developed somewhat independently of one another. Those publishing in one are well insulated from the ideas exposed in another. This is an intellectually unhealthy situation in need of a remedy. Clare Harries and Mandeep Dhami organised a symposium at the 17th Conference on Subjective Probability, Utility and Decision Making in an attempt to provide one. They invited different speakers to outline those approaches to studying judgement that they had found particularly interesting or useful. The papers in this Special Issue are derived from presentations at that symposium. All of them have been subject to refereeing of the same nature and standard as other papers submitted to the journal.The four main papers included here provide critical reviews that describe and compare different approaches. As a set, the papers provide concise state-of-the-art accounts of the strengths and weaknesses of different approaches to studying judgement. However, they also provoke a numer of questions: certain of them are specific to particular approaches but others are much more general. Some of these questions are discussed in the two short commentaries that conclude the issue.
