# Philosophy of Logic

**Type:** Concept  
**Domain:** foundations-logic  
**Codex URL:** /mathematics/foundations-logic/philosophy-of-logic/  
**Entry status:** Live — v1.0 (2026-07-09)

## Summary
Examines what makes logical inference valid, the nature of logical laws, and the plurality of logics. Key positions: logicism (Frege/Russell), formalism (Hilbert), intuitionism (Brouwer), Platonism. Tarski's truth hierarchy, liar paradox, logical pluralism.

## Sources
- [Tier 1] Frege, G. (1879). Begriffsschrift. Trans. Bynum 1972. Oxford University Press.
- [Tier 1] Tarski, A. (1935). Der Wahrheitsbegriff in den formalisierten Sprachen. Studia Philosophica, 1, 261-405.
- [Tier 2] Beall, J.C. and Restall, G. (2006). Logical Pluralism. Oxford University Press.
- [Tier 3] Priest, G. (2008). An Introduction to Non-Classical Logic. 2nd ed.

---
*Mathematics Codex entry v1.0 — added 2026-07-09 — thecodex.expert/mathematics/*