Chesterman agrees that translation and interpreting studies should be seen as belonging to the same general field. He underlines the value of joint projects in translation research and outlines an attempt to set up such a project in Helsinki. He questions the value of disciplinary autonomy from a research point of view, as opposed to the institutional point of view. Chesterman briefly discusses different opinions of the relation between theory and data in empirical and hermeneutic research. These differences derive partly from different interpretations of the concept of a theory, and of the relative importance of facts versus ideas. In assessing theories, we also appeal to pragmatic criteria, not only truth-based criteria. The theory-data relation may be the weaker one of illustration, not only the stronger ones of testing or falsification. Chesterman defends a Propperian approach to research, based on the testing of hypotheses. A Propperian view can also help us to understand claims of progress in translation research.