The UConn Logic Colloquium on Friday, 7 May 2021, at 10am EST (online) will feature Alessandro Zucchi (University Of Milan). Title, abstract and zoom information below.

Minimal Change Theories Of Conditionals: The Import-Export Law And Modus Ponens

Abstract: Stalnaker’s minimal change semantics for conditionals fails to support the import-export law according to which (a) and (b) are logically equivalent:

(a) if A then if B then C
(b) if A and B then C

However natural language conditionals seem to abide by the law. McGee (1985) outlines a minimal change semantics for conditionals that supports it. I argue that in fact the equivalence between (a) and (b) does not hold unrestrictedly and I suggest that the facts follow from the interaction between the semantics of conditionals and the ways suppositions may affect the context. I conclude by describing the consequences of my account for the issue of the validity of modus ponens.