A Counterexample to Modus Tollens Seth Yalcin

Abstract

This paper defends a counterexample to Modus Tollens, and uses
it to draw some conclusions about the logic and semantics of indicative
conditionals and probability operators in natural language. Along the way
we investigate some of the interactions of these expressions with knows, and
we call into question the thesis that all knowledge ascriptions have truthconditions.
Aprobabilistic dynamic semantics for probability operators, conditionals,
and acceptance attitudes is developed around the idea of representing
the common ground of a conversation as a set of probability spaces.