Phenomenology is not realism, in that the real is dependent on Dasein‘s understanding of being (Seinsverständnis) without which sense data make no sense to it. Sense is not borne out by perception per se; it is existentially mediated qua Dasein. Phenomenology is not idealism either, because it accepts the reality of the external world; Dasein is being-in-the-world (In-der-Welt-sein). It is just that for a phenomenologist, it does not make sense to talk about the real world without understanding what being is first. It is the task of philosophical phenomenology to elevate Dasein‘s understanding of being above and beyond the pre-ontological level of understanding that characterises the naïveté of common sense.
Understanding of being precedes perception: hermeneutica a priori