On Moderate Pluralism About Truth and Logic

According to moderate truth pluralism, truth is both One and Many. There is a single truth property that applies across all truth-apt domains of discourse, but instances of this property are grounded in different ways. Propositions concerning medium-sized dry goods might be true in virtue of corresponding with reality while propositions pertaining to the law might be true in virtue of cohering with the body of law. Moderate truth pluralists must answer two questions concerning logic: (Q1) Which logic governs inferences concerning each truth-apt domain considered separately? (Q2) Which logic governs inferences that involve several truth-apt domains? This paper has three objectives. The first objective is to present and explain the moderate pluralist’s answers to (Q1) and (Q2). The second objective is to argue that there is a tension between these answers. The answer to (Q1) involves a commitment to a form of logical pluralism. However, reflection on the moderate truth pluralist’s answer to (Q2) shows that they are committed to taking logic to be topic neutrality. This, in turn, forces a commitment to logical monism. It would seem that the moderate truth pluralist cannot have it both ways. The third objective is constructive in nature. I offer an account of what moderate truth pluralists should say about logic and how they might resolve the tension in their view. I suggest that, just like moderate truth pluralists distinguish truth proper and “quasi-truth,” they should endorse a distinction between logic proper and “quasi-logic.” Quasi-truth is truth-like in the sense that instances of quasi-truth ground instances of truth. Quasi-logic is logic-like in the sense that it concerns arguments that are necessarily truth-preserving but are not generally so in a topic neutral way. I suggest that moderate truth pluralists should be monists about truth proper and logic proper but pluralists about quasi-truth and quasi-logic. This allows them to say that logic proper is topic neutral while still accommodating the idea that, for different domains, different arguments may be necessarily truth-preserving.