Ampliative Adaptive Logics and the Foundation of Logic-Based Approaches to Abduction

Abstract

In this paper, we propose a reconstruction of logic-based approaches toabductive reasoning in terms of ampliative adaptive logics. The advantagesof this reconstruction are important: the resulting logics have a propertheory (that leads to justified conclusions even for undecidablefragments), they nicely integrate deductive and abductive steps, and theyare much closer to natural reasoning than the existing systems.We present two new adaptive logics for abduction, CP1 and CP2. CP1 enables one to generate explanations for novel factsfrom a consistent theory. CP2 moreover enables one to abduceexplanatory hypotheses for novel facts and for anomalous facts from apossibly inconsistent theory. We illustrate both logics with some examplesfrom the history of the sciences (the discovery of Uranus and of Neptune),and present some alternatives to CP1 and CP2 that are bettersuited for non-creative forms of abductive reasoning and for practicalreasoning.