Abstract: We propose a principled distinction between two types of inferences: ‘intuitive inference’ and ‘reflective inference’ (or reasoning proper). We ground this distinction in a massively modular view of the human mind where metarepresentational modules play an important role in explaining the peculiarities of human psychological evolution. We defend the hypothesis that the main function of reflective inference is to produce and evaluate arguments occurring in interpersonal communication (rather than to help individual ratiocination). This function, we claim, helps explain important aspects of reasoning. We review some of the existing evidence and argue that it gives support to this approach.