Substitution in Material Inference and Logical Environments

Standard - GACR GA26-22448S [Registered results] 2026 - 2028

Principal Investigator: Ing. Wesley Fussner, Ph.D.

Logical inferences are typically thought as those inferences that hold by virtue of the form of the involved statements rather than their meaning. In contrast, material inferences are those that hold due to the meaning of the implicated statements. A prominent line of thought — represented by the work of W. Sellars and R. Brandom — argues that most important inferences are material in nature rather than logical.

This project aims to develop a metatheoretical basis for thinking about the relation between logical and material inferences, using the universally agreed-upon importance of substitution as an anchor point.

The project will deploy three approaches in order to develop the proposed metatheoretical framework: A "bottom-up" hierarchical approach that takes logical inference as something done to statements that come pre-equipped with material relationships; a "same level" approach that understands material inference and logical inferences as obeying different inferential standard; and a "top-down" approach reconstructing logical consequence as a fragment of material consequence.

Project Aims

  1. Develop a cohesive framework that integrates material and logical inference.
  2. Clarify the role of substitution at the interface of material and logical inference.
  3. Explicate the nature of logical variables.