The probabilistic turn

This chapter aims to outline the so-called ‘probabilistic turn’: a move from using logic to using probability theory as a framework for understanding human thought. This probabilistic turn has occurred primarily over the last ten to fifteen years across a range of disciplines. The chapter begins by considering the probabilistic turn in the semantics of natural language, i.e. the project of specifying a formal theory of meaning for natural language statements, and thus specifying which inferences follow from such statements. It considers how probabilistic approaches have become prevalent in the three areas that were considered in relation to logic-based methods. In each of these areas — theories of scientific inference, artificial intelligence, and psychology — the discussion will be broadened to consider relevant research across related disciplines. The chapter thus provides historical and technical background for the development of the specific probabilistic theories of performance on the three key areas of human reasoning: conditional reasoning, the selection task, and syllogistic reasoning.