Abstract

This paper considers the classification in terms of "relative validity" of arguments that are taken to be good arguments in an informal setting, despite not being strictly or absolutely valid. It employs Timothy Smiley’s framework for relative validity in his ‘A tale of two tortoises’ (1995). Everyday arguments can rely on rules of inference that are not formally valid: such rules can be presumed to be good ones in the context, just as context can justify suppressed premises relied upon in other arguments. The paper goes on to draw on Smiley’s discussion of suppressed rules and relative consequence in considering arguments involving vague predicates. In particular, it examines Delia Graff Fara’s account of relative validity within the framework of a supervaluationist theory of vagueness, arguing that Smiley’s discussion suggests objections to Fara’s account and allows us to respond to the criticisms that she levels at the supervaluationist theory of vagueness. Further features and merits of Smiley’s framework are thereby revealed.