Social pragmatic factors in reasoning from disjunctions of numerical estimations


The paper presents two studies that investigated how individuals reason from disjunctive statements that use numerical estimations. In the experiments two types of such statements were used. In the first type both constituents of a disjunction could be a logically correct answer. That is, if “The average life time of a fruit fly is either 9 or 27 days”, any of those numbers is logically possible. In the second type that truth of one constituent excluded the truth of the other, e.g. “The average time of holidays in the EU is either higher than 9 days or else higher than 27 days”. A simple repetition of any of those figures is an illusory inference as it renders both constituents true. The results of Experiment 1 proved that although the participants showed a tendency to repeat one of the disjuncts as their answer, this tendency was smaller when the content of the statements referred to politics and social life in comparison with the general knowledge questions. The results of Experiment 2 showed that individuals reveal the tendency to repeat opinions coming from speakers who are more likeable, even if such opinions are incorrect illusory inferences. The results of both studies show that illusory inferences appear also in the domain of numerical cognition but they may be reduced by pragmatic factors such as the content of the message and the knowledge about its source.

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