In § 7(c) of Being and time, Heidegger takes great care to explain the importance of understanding the essence of phenomenon as making manifest, such that visibility belongs to the very meaning of phenomenon itself. Phenomenology, as the logos of phenomenon, is an investigation into the fundamental visibility of being – a special moment of uncovering which is captured in the ancient Greek term aletheia.
Viewed in this light, it is clear why Heidegger approaches and uses phenomenology as an ontology: for phenomenon to become “phenomenologically relevant” (Heidegger, 1996, p. 33), it has to be accessed in the context of the meaning of being (Sinn von Sein) in beings (Seiende). In being-in-the-world as the primary mode of being on earth, there is only one kind of being that can question the meaning of being – and that is Dasein. This ontological priority of Dasein provides the reason for Heidegger’s introduction of fundamental ontology in Being and time. Phenomenology, in Heidegger’s hands, becomes fundamental ontology. This is the first important standpoint Heidegger takes vis-à-vis the history of Western philosophy. The second important standpoint taken by Heidegger is that, by virtue of the ontological priority of Dasein, phenomenology as fundamental ontology is essentially hermeneutic in method and character. This is because the essence of Dasein‘s comportment to being (Seinsverhältnis) is understanding of being (Seinsverständnis), which Dasein accesses through interpretation – the mediation of “subjectivity” and its “fore-structure” (Vor-Struktur), so to speak. In other words, phenomenology, as fundamental ontology, is hermeneutics.
To quote from § 7(c) what is methodologically speaking the most important passage in Being and time: