How Inference Can Be Explained in Terms of Logical Consequence

Rachel Boddy (IUSS Pavia)

11 April 2025, 16:00 (Lisbon Time – WET)

Faculdade de Letras de Lisboa

Sala Mattos Romão [C201.J] (Departamento de Filosofia)

Abstract: Philosophers have held that validity of inference can be explained in terms of logical consequence. In today’s debate on the normativity of logic, however, it is commonly taken for granted that this view is mistaken. Harman’s (1986) criticism appears to have settled the matter: Current logic fails to explain what beliefs may or should be inferred from what other beliefs. The issue here is that logical principles are not defeasible, whereas principles of belief revision are. I argue that this criticism does not settle the matter because it relies on a notion of inference that logical accounts do not share. The focus of this talk is on the question this raises: What is an inference supposed to be in logic? Starting from the view that inference is an epistemic notion, I argue that the notion of inference at play in logic should be expressed in terms of knowledge, not in terms of belief.