Testimony and argument: a Bayesian perspective

Philosophers have become increasingly interested in testimony (e.g. Coady, Testimony: A philosophical study. Oxford University Press, Oxford, 1992; Kusch & Lipton, Stud Hist Philos Sci 33:209–217). In the context of argumentation and persuasion, the distinction between the content of a message and its source is a natural and important one. The distinction has consequently attracted considerable attention within psychological research. There has also been a range of normative attempts to deal with the question of how source and message characteristics should combine to give rise to an overall evaluation of evidential strength (e.g. Walton, Witness testimony evidence: Argumentation, artificial intelligence, and law. Cambridge University Press, Cambridge, 2008). This chapter treats this issue from the perspective of the Bayesian approach to argument (Hahn & Oaksford, Psychol Rev 114:704–732, 2007a; Hahn et al., Informal Log 29:337–367, 2009) and summarises empirical evidence on key intuitions.