Renee Elio, Francis Jeffry Pelletier
We report empirical results on factors that influence human default reasoning, both in feature-inheritance type problems and in problems that specify information about exceptions to default rules. These factors include similarity between instances that are reasoned about and whether the classes of the instances are naturallyoccurring or classes of artifacts. While in classical deductive logic, a problem’s 'correct answer' is defined by the problem’s formal structure, we argue that the case is different for default reasoning. The identification of factors that influence people’s default inferences can contribute to more robust theories of default reasoning that include principles of relevance.