Pluralism in reasoning: how to legitimate material inferences

Wilfrid Sellars’s suggestion that there are valid material inferences entails that validity is not limited to formal inferences. Because material inferences are expressed in ordinary language and deal with both conceptual and empirical matters, an interesting prospect unfolds: valid reasoning is irreducibly plural. However, it is not clear what the validity of inferences composed of non-logical and descriptive vocabulary means. I argue that it is better to speak of the legitimacy rather than the validity of material inferences. A material inference can be understood as legitimate when one has a pragmatic propriety to infer from an assertion A to an assertion B. Pragmatic propriety designates the social-normative entitlement of inferencing. Because pragmatic proprieties are discipline-specific and local, legitimate reasoning is plural. Nevertheless, the shared general feature of reasoning practices is to preserve and improve the coherence of one’s system of belief.