The presumption of assurance

Abstract

According to the Assurance Theory of testimony, in telling an audience something, a speaker offers their assurance that what is told is true, which is something like their guarantee, or promise, of truth. However, speakers also tell lies and say things they do not have the authority to back up. So why does understanding tellings to be a form of assurance explain how tellings can provide a reason for belief? This paper argues that reasons come once it is recognised that tellings are trusted. And the logic by means of which trust gives reason to believe is quite general; it applies equally to belief that is based on evidence rather than assurance. Outlining this logic requires the introduction of the idea of epistemic presumptions, whose truth plays the role of ensuring a connection between believer, justification and truth.