Gilbert Harman, in ‘Logic and Reasoning’ (Synthese 60 (1984), 107–127) describes an “unsuccessful attempt ... to develop a theory which would give logic a special role in reasoning”. Here reasoning is psychological, “a procedure for revising one's beliefs”. In the present paper, I construe reasoning sociologically, as a process of linguistic interaction; and show how both reasoning in the psychologistic sense and logic are related to that process.