Another way logic might be normative

Abstract

Is logic normative for reasoning? In the wake of work by Gilbert Harman and John MacFarlane, this question has been reduced to: are there any adequate bridge principles which link logical facts to normative constraints on reasoning? Hitherto, defenders of the normativity of logic have exclusively focussed on identifying adequate validity bridge principles: principles linking validity facts—facts of the form Γ⊧ φ—to normative constraints on reasoning. This paper argues for two claims. First, for the time being at least, Harman’s challenge cannot be surmounted by articulating validity bridge principles. Second, Harman’s challenge can be met by articulating invalidity bridge principles: principles linking invalidity facts of the form Γ⊭ ψ to normative constraints on reasoning. In doing so, I provide a novel defence of the normativity of logic.