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.

In categorical explanation a category label is used to explain an associated property. We show that label entrenchment,whether a label is commonly used by ones community, affects the judged quality of a categorical explanation whetherthe explanation offers substantive information or not. In Experiments 1 and 2, explanations using unentrenched labels arerated as less comprehensive and less natural independent of causal or featural information, even when the label is merely aname for the explanandum. Experiments 3 and 4 replicate the effect with unentrenched labels coined by groups of expertdiscoverers and rule out explanations like familiarity and communicative principles. Most participants in Experiments3 and 4 could not report the impact of entrenchment on their judgments. We argue that reliance on entrenchment arosebecause the community often has useful information. Common use of labels as conduits for this knowledge inducesreliance on community cues even when uninformative.

Does the ability to reason well make one less likely to engage in motivated reasoning? Following a paradigm used by Kahan, Peters, Dawson, and Slovic (2013), this study aims to replicate, extend, and explain the surprising finding that those most likely to process politicized data in a biased manner are those who score highest on a measure of numerical proficiency. Although our study found general effects of motivated reasoning, we failed to replicate Kahan et al.’s “motivated numeracy effect”. However, our study did find that, when forced to consider competing statistical interpretations of the data before responding, highly numerate participants were more likely than less numerate ones to choose a correct but belief-contradicting interpretation of data. These results suggest that while numerate participants were biased when generating responses, they were not when evaluating reasons to justify their responses