Value judgments, prescriptions and proscriptions concerning instructional proposals seem to be very frequent in works in Didactics (papers, communications,…). In this paper we tackle the question of whether claims of this kind are legitimate. In few words, we wonder whether didactics can say how to teach. For that, we analyse and compare the answers to this question of several scholars working in different approaches. In this way, we would like to start a dialogue aimed at laying the foundations for a better understanding and a scientific cooperation between different theories in Didactics.