Fallacies and biases The case of the straw man

When processing political arguments, people are strongly affected by their prior ideological beliefs. Political cognition often relies on two types of ideological biases. Firstly, confirmation bias leads addressees of political communication to accept arguments that affirm their preferred ideological positions. Secondly, disconfirmation bias probes reasoners to reject arguments that provide attitudinally incongruent evidence. Here, we report the findings of an experiment aimed at investigating the role of biased reasoning on perceptions of argument soundness. We focused on the processing of the strawman fallacy to determine whether strawman effectiveness is contingent upon the activation of different ideological biases. We examined argument comprehension, argument evaluation and fallacy identification by means of a memory task, a rating task and an interview. Our data suggests that ideological biases and fallacy effect are associated with deliberative cognitive settings and marks a distinction between evaluative attitudes and the capacity to identify fallacies in political argumentation.