CATEGORICAL INFERENCE IS NOT A TREE - THE MYTH OF INHERITANCE HIERARCHIES

One enduring principle of rational inference is category inclusion: Ca tegories inherit the properties of their superordinates. In five exper iments, I show that people do not consistently apply this principle wh en evaluating categorical arguments involving natural categories and a single nonexplainable predicate such as all electronic equipment has pal-ts made of germanium, therefore all stereos have parts made of ger manium. Participants frequently did not apply the category inclusion r ule despite affirming the relevant categorical relation (e.g., stereos are electronic equipment). They failed to apply the rule even when ca tegories were universally quantified unambiguously. Instead, judgments tended to be proportional to the similarity between premise and concl usion categories. Neglect of category inclusion relations was observed using arguments concerning natural kinds, artifacts, and social kinds . (C) 1998 Academic Press.