In this episode we speak with Martin Dufwenberg about his paper Promises and Partnership, which he co-authored with Gary Charness and which was published in Econometrica in 2006. The paper investigates whether communication affects the outcomes in trust games in line with the predictions of guilt aversion. Among other topics, we discuss the story behind the writing of the paper, the reception it received since it was published, and the advantages of having a formal theory before running an experiment.