Degrees of assertability

In considering what we ought to say, we can evaluate a proposition both for whether it is assertable and for how assertable it is. The latter notion, that of comparative assertability, has an important role to play, both in our epistemic evaluations of speech and in our pragmatic reasoning. Yet, despite this, it has received little prior discussion.

This paper takes up the investigation of comparative assertability. §§1–2 provide a preliminary, informal overview of the topic and an operationalization of the target notion. §3 introduces Probabilism, the thesis that a proposition's degree of assertability is determined by its probability. Probabilism has been assumed in much of what prior discussion on comparative assertability there is. In §4 I present two kinds of problem for Probabilism—problems which, I suggest, when taken in combination, should lead us to look for alternatives. In §5, I formulate and defend one such alternative. Under this proposal, comparative assertability is a matter, not of comparative probability, but of comparative normality. I conclude by demonstrating how adopting this approach allows us to avoid both kinds of problem which beset Probabilism.