Formalizing the Interaction Between Evidentiality and Egophoricity: A Multi-Modal Logic for Tibetan Epistemic Systems

Golog Tibetan grammaticalizes both evidentiality and egophoricity, but the two categories interact in a constrained way: evidential marking neutralizes the binary egophoric versus non-egophoric contrast. This paper develops LEE (Logic of Evidentiality and Egophoricity), a multi-modal logic that formalizes this interaction. LEE employs operators □EGO, □SENS, and □INF for egophoric, sensory-evidential, and inferential-evidential markers, respectively. The blocking effect is captured by axioms □σφ → (□EGOφ ↔ ◇EGOφ) for σ ∈ SENS, INF. This paper establishes soundness, completeness, and decidability for LEE. Three empirical puzzles receive unified explanation: (i) blocking of egophoric vs. non-egophoric contrasts under evidential marking, (ii) semantic bleaching of egophoric morphology in evidential contexts, and (iii) the unidirectional nature of the evidential–egophoric interaction.