ABSTRACT
David Over is a leading figure in the psychology of reasoning and rationality, and in this introduction we sketch the background conditions that led to this role. His academic base was in philosophical logic, in particular the role of the conditional, if. He was strongly influenced by the ideas of J.L. Austin. He began a cross-disciplinary approach to this topic in collaboration, firstly, with Ken Manktelow and latterly with his major associate Jonathan Evans. With Manktelow, he advanced a decision-theoretical approach to deontic reasoning, a challenge to the prevailing schema theories, of which they were critical. With Evans, he first produced an extension of the dual process theory of reasoning and a dual theory of rationality, in their first book, and then established a major new theory of the conditional, the suppositional theory, in their second. These formed the basis of what he termed a ‘new paradigm’ in the study of reasoning, one based on probability rather than the previous framework of two-valued logic. Following Evans’ retirement, David has continued his prolific output of research and theory with a number of international collaborators; his focus remains on the conditional.
