Connecting Free Choice Permission with Obligation and Prohibition by Not Doing It

DEONProceeding Paper
Zilu Wang and Yanjing Wang
Proceedings of DEON 25
Publication year: 2025

n this paper, we propose a bundle-based framework of deontic logic with permission, obligation, and prohibition, based on our previous work on free choice (strong) permission. The key is to introduce the negated action types such that $\neg\alpha$ captures the idea of \textit{not doing $\alpha$}. This negation can naturally connect weak obligation and prohibition to strong permission. It also helps to define weak permission and strong obligation. Under various model classes, we give several sound and complete proof systems with strong permission, weak obligation, and prohibition modalities. We also compare our work with Fine’s deontic logic based on truthmaking semantics.

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Strong Permission Bundled: First Steps

DEONProceeding Paper
Zilu Wang, Yanjing Wang
Proceedings of DEON 2023
Publication year: 2023

In this paper, we introduce a novel framework for deontic logic of strong permission that accommodates free choice. Our approach treats permission as a bundled modality, which combines a universal quantifier with a possibility modality such that an action type \alpha is permitted if and only if every token of \alpha can be executed in some deontically ideal world. Our formalization of action tokens and their types is inspired by the BHK-style interpretation for intuitionistic logic. We axiomatize the logics of strong permission under various conditions. In addition to satisfying the desirable logical requirements found in the literature, our framework also predicts interesting new phenomena related to permission and distribution laws that align with our linguistic intuition.