A Novel Semantics for Belief, Knowledge and Psychological Alethic Modality

The problem of logical omniscience—the assumption that agents know all logical consequences of their beliefs—has prompted many proposed solutions, but most merely tweak standard Kripke semantics without engaging with psychological mechanisms. This paper introduces a psychologically grounded approach called PQG logic, built on fundamental units of percepts, qualia, and cognitions. From these building blocks, it develops a novel semantics for belief, knowledge, psychological necessity, and possibility. The framework aims to address logical omniscience and to better understand the psychological-logical nature of belief and knowledge.

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Abstract

Recently there have been numerous proposed solutions to the problem of logical omniscience in doxastic and epistemic logic. Though these solutions display an impressive breadth of subtlety and motivation, the crux of these approaches seems to have a common theme-minor revisions around the ubiquitous Kripke semantics-rooted approach. In addition, the psychological mechanisms at work in and around both belief and knowledge have been left largely untouched. In this paper, we cut straight to the core of the problem of logical omniscience, taking a psychologically-rooted approach, taking as bedrock the "quanta" of given percepts, qualia and cognitions, terming our approach "PQG logic", short for percept, qualia, cognition logic. Building atop these quanta, we reach a novel semantics of belief, knowledge, in addition to a semantics for psychological necessity and possibility. With these notions we are well-equipped to not only address the problem of logical omniscience but to more deeply investigate the psychical-logical nature of belief and knowledge.