Abstract: Speakers in conversational discussions are often confronted with the task of formulating themselves unrehearsed. Speaker and listener cooperate to construct an interpretation of their experience of the world, their part in the world, and the world of experience within them, that can be evaluated by a listener as next speaker or by the very same speaker who was primarily responsible for the production of the formulation in the first instance. This process of local cooperative and mutual co-construction and evaluation of interpretations of experience I refer to as a course of development. In a course of development an interpretation of reality (social or otherwise) is interactively and rhetorically worked up and dialectically worked through for coherence, relevance, tenability, consequences, etc. Excerpts from conversational discussions are used to demonstrate the interactive rhetorical and dialectical work speakers and listeners carry out in an effort to make sense of their experience of the world and their relationship to the world and each other. Ways of talking are analysed as means of constructing restricted world-views that do not so much rely or depend on the grammar of the particular language as on the dialogical-dialectical work of the speakers and listeners. The notions of horizon, perspective, appresentation, and apperception developed by Husserl for the phenomenology of individual perception are generalized to incorporate the mutual and cooperative calibration of consciousness evidenced in a course of development in conversational discussion. Contributions to an on-going discussion are claimed to constitute -passing theories- (a la Davidson) actualized in real time in the talk where the Husserlian notions of horizon, perspective, etc. of individual subjective consciousness are in a sense turned inside out in the establishment and maintenance of inter-subjective consciousness in relation to the topics and the events under development in the conversation.