Title: The Logic of Plausible Reasoning: A Core Theory
Abstract: The paper presents a core theory of human plausible reasoning based on analysis of people's answers to everyday questions about the world. The theory consists of three parts: a formal representation of plausible inference patterns; such as deductions, inductions, and analogies, that are frequently employed in answering everyday questions; a set of parameters, such as conditional likelihood, typicality, and similarity, that affect the certainty of people's answers to such questions; and a system relating the different plausible inference patterns and the different certainty parameters. This is one of the first attempts to construct a formal theory that addresses both the semantic and parametric aspects of the kind of everyday reasoning that pervades. all of human discourse.