Cogency and Question‐Begging: Some Reflections on McKinsey's Paradox and Putnam's Proof

A cogent argument is one whereby someone could be moved to rational conviction of the truth of its conclusion. So a chain of valid inferences cannot be cogent if only someone who already took themselves to be rationally persuaded of the conclusion could rationally receive whatever grounds purportedly warranted its premises as doing just that. Say that a particular warrant, w, transmits across a valid argument just in case the argument is cogent when w is the warrant for its premises. We need to note immediately a distinction between transmission of warrant, so characterised, and closure of warrant. Closure of warrant across entailment has of course been very widely discussed.' It is the weaker principle. Closure, unrestricted, says that whenever there is warrant for the premises of valid argument, there is warrant for the conclusion too. Transmis-