Proceedings of the Annual Meeting of the Cognitive Science Society

A connectionist model of argument strength, which applies to arguments involving natural categories and unfamiliar predicates, was proposed by Sloman (1991). The model applies to arguments such as robins have sesamoid bones, therefore hawks have sesamoid bones. The model is based on the hypothesis that argument strength is related to the proportion of the conclusion category's features that are shared by the premise categories. The model assumes a two-stage process in which premises are first encoded by connecting the features of premise categories to the predicate. Conclusions are then tested by examining the degree of activation of the predicate upon presentation of the features of the conclusion category. The current work extends the domain of the model to arguments with familiar predicates which are nonexplainable in the sense that the relation between the category and predicate of each statement is difficult to explain. W e report an experiment which demonstrates that both of the phenomena observed with single-premise specific arguments involving unfamiliar predicates are also observed using nonexplainable predicates. W e also show that the feature-based model can fit quantitatively subjects' judgments of the strengdi of arguments with familiar but nonexplainable predicates.