Through a hermeneutic-phenomenological reading we show the methodological commitments that support the approach of the interexistential theme, eminently in §26 of Being and Time and in constant consideration of its location and systematic dependence. This clarification allows, in positive contrast with the analysis of the world-environment of being-at-hand, to explain why the interexistential inquiry is set in motion within the primary daily horizon where the others are previously open, both mediately as intentional reference in the world-environment, as well as immediately (...) in the shared world. This initial approach in daily life is an inevitable methodological demand for the successful witnessing of the most basic being-with-another, thanks to which Heidegger manages to unveil the essential and a priori ontological structure of da-sein as being-with. (shrink)