Humans Reason Skeptically

Abstract

The weak completion semantics is a novel cognitive theory. It is multi-valued, non-monotonic, and knowledge-rich, allows learning, can handle inconsistent background knowledge, and can be applied to model the average reasoner. Moreover, it uses abduction to explain observations, to satisfy integrity constraints, and to search for counterexamples. In all these applications, human reasoning tasks can only be adequately modeled within the weak completion semantics if skeptical abduction rather than credulous abduction is applied. This will be illustrated in the context of the suppression task, disjunctive reasoning, and conditional reasoning.