This special issue of "Thinking and Reasoning" is devoted to social judgement theory SJT, which has its origins in Egon Brunswik's probabilistic functionalism.; The first paper discusses the history and theory of SJT and explores Hammond's distinction between coherence and correspondence criteria. The next paper presents the major methodological approaches of SJT, with a focus on the Lens Model. Four applications follow, including an exploration of the medical applications of SJT.