Time: Wed 27 May 2026, at 12:10

Place: Room B112, Building 2, Lee Shau Kee Humanities Hall

Speaker: WANG Zilu(MA Student), Peking University

Language: Chinese and English

This event is part of the Philosophy Symposium Series.

Abstract:

Deontic logic is a branch of modal logic studying the logical behaviors of normative concepts such as obligation, permission, and prohibition. These deontic modalities are typically applied to actions rather than propositions, e.g., "Alice ought to pay taxes", "You may have a cake or an ice cream", "Smoking is forbidden here". So, any adequate account of deontic modalities should be accompanied by a suitable treatment of actions. Many existing approaches to deontic logic either interpret deontic modalities as normal modal operators or assume that actions constitute a Boolean algebra. However, these treatments give rise to numerous deontic paradoxes where logical systems predict counter-intuitive inference patterns, especially concerning the notion of permission. In our previous work (2023, 2025), we proposed a novel semantic framework for deontic action logic of strong permission. Based on a formalized BHK-style interpretation of action types as sets of action tokens, we interpret strong permission as a bundle of ∀♢ such that an action type is strongly permitted iff each token of the type is executed at some deontically ideal world. Our semantics not only resolves well-known paradoxes, but also predicts many intuitively invalid inferences inherent to the Boolean treatment of action types. We further enrich this framework with preference semantics and update operators to model conditional norms. In this talk, I will present several deontic paradoxes concerning permission at three levels and demonstrate how our bundled framework for deontic action logic naturally addresses them.