On the Normativity and Plurality of Logical Consequence: Some Reflections on the Role of Logic in Our Epistemic System

This thesis focuses on two topics at the core of current debates in the philosophy of logic: the normativity of logic and logical pluralism. The first chapter begins with an overview of the alternative conceptions of logic, and then presents the state of the art on the normativity of logic and logical pluralism. In the second chapter, I provide an account of the normativity of logic as sourced in rationality according to which being evaluated against a standard of formal cogency is constitutive of being rational. There are two main innovations in support of this treatment of logic’s normativity. First, while there is a lively debate nowadays on what the connection is between logic and norms for reasoning, there is little discussion on the nature and the source of the normativity of logic. Second, adopting this view gives logical pluralists a new way to treat the objection that logical pluralism is incompatible with the claim that logic is normative for reasoning. This objective is developed in the third chapter, where I also argue that my proposal, while accommodating both monist and pluralist accounts of logic, provides support for a form of pluralism about logical consequence. The fourth chapter considers two ways to extend my proposal. First, I discuss an important issue concerning the epistemic significance of adopting logical pluralism. I argue that, since the logical pluralist endorses more than one validity relation, she has additional conditions for transmitting justification. Further, I suggest that the logical pluralist should adopt contextualism about deductive justification. Second, I develop the prospects of combining logical pluralism with pluralism about truth. One way to do this is to claim that different truth properties and different consequence relations operate in different domains. I contend that this form of pluralism is based on commitments that are co-untenable.