This paper starts of with the story of Sizwe and his hesitancy about testing for HIV and AIDS. The story is used as a case study to illustrate an interdisciplinary process. The author proposes postfoundationalism and especially transversal rationality as a practical way of guiding the interdisciplinary discussion. Six scholars from different disciplines were asked to respond on the story of Sizwe. The author then reflects on these responses in an effort to create practical guidelines for an interdisciplinary process of transversal rationality. The reflection in this paper represents a third movement of reflection. The first was done in a paper delivered at a congress, and the second in the article that was published.