1941 – 2021
J. Michael Dunn (1941–2021) was an American logician and philosopher at Indiana University, widely recognized as a foundational figure in relevant logic and non-classical logics. He developed the Belnap-Dunn four-valued logic (FDE) and made major contributions to the semantic foundations of substructural and paraconsistent logics. His work bridged formal logic, computer science, and metaphysics.
Co-developed the Belnap-Dunn four-valued logic (First Degree Entailment, FDE), foundational to paraconsistent and relevance logic
Provided influential relational semantics ('star semantics') for relevant logic
Developed gaggle theory, generalizing residuation and Galois connections across substructural logics
Co-authored foundational work on entailment with Anderson and Belnap
Contributed to information-based interpretations of logical connectives