Being and Time begins very appropriately with a critical assessment of Plato’s Sophist, which seems poised to position Heidegger’s investigation in the same investigative lineage as Plato. By pointing out Plato’s own admission that the expression of Being—Heidegger is aware of the elusiveness of not just the practicality of Being, but the overarching theory that proceeds the term.
So, Heidegger’s first task is to re-conceptualize Being by finding a way to appropriately ask: what is Being? In particular, how has this “what-ness” been misunderstood. This task is critical to Heidegger’s approach to Being, since Heidegger argues that the question of Being has not been asked correctly—that is to say, concretely—and this, in turn, has led to the term’s elusiveness for Plato. If, as Plato confirms, Heidegger suggests that we must rethink the kind of thought (i.e. as Heidegger argues in his Parmenides lecture) necessary to ask the question of Being the right way. To do so, this means setting aside the tradition of Being—as it has been forgotten and misunderstood—in order to, as Heidegger argues, “reawaken an understanding for the meaning of [the question of the meaning of Being].” In doing so, Heidegger believes that the way to offer the “meaning” of the question of Being is to destroy how this meaning has been disseminated by traditional ontology post-Plato—the question of Being, as such, has its “meaning” incorrectly conceptualized by the tradition of ontology, to the extent that what Being is (i.e. its metaphysics), consequently, becomes a question left woefully unanswered in its traditional interpretation. Because of this, Heidegger sets the “provisional aim” of Being and Time towards an understanding the meaning of the question of Being by “the possible horizon” of the “Interpretation of time.”
Before suggesting what this “Interpretation of time” as a “possible horizon” for understanding Being would look like, Heidegger calls for some “introductory remarks” situated on the “exposition of the question of the meaning of Being.” Such an “exposition” attempts to avoid “dogma” that “declares” the question itself—of the meaning of Being—“superfluous” on one hand, and on the other, “sanctions its complete neglect.” But more importantly, since Being is “rooted in ancient ontology,” there are certain categorical imperatives (of ontology) that Heidegger highlights as three “presuppositions”: 1.) that Being is “the most universal concept,” 2.) that Being is “indefinable,” and 3.) that Being is “of all concepts the one that is self-evident.”
In light of these “prejudices,” as Heidegger calls them, the question of Being not only “lacks an answer, but that question itself is obscure and without direction.” What this means, then, is that there must be a “formal structure of the question of Being” constructed around an inquiry based on three interrogative elements: that which is asked about, that which is interrogated, and that which is to be found out by asking. For Heidegger, these “constitutive factors” reveal, through inquiry, that “the meaning of Being must already be made available to us in some way”—in other words, by formulating this inquiry into question about Being, what is required, then, is an explanation of “how Being is looked at, how its meaning is to be understood and conceptually grasped.” As a result, Heidegger suggests that “it requires us to prepare the way for choosing the right entity…and to work out the genuine way of access to it”—this entity, as the inquirer, is “transparent in his own Being,” because “the very asking of [the question of Being] is [this] entity’s mode of Being.” This entity that Heidegger contends “gets its essential character from what is inquired about Being” is the entity “which each of us is himself and which includes inquiring as one of the possibilities of its Being”: this entity is denoted by the term “Dasein,” fundamentally grounded on ontological and ontical priorities.
The ontological priority of the question of Being as the extent to which “Being is always the Being of an entity” through the totality of entities in conjunction with the ontical priority of the question of Being as the degree to which Dasein “always understands itself in terms of its existence” illustrates Dasein’s ontico-ontological priority, as it shapes Heidegger’s analytic of Dasein. By way of this analytic, Dasein’s essentia resides in its ability “to be,” while the means by which we can speak of it (at all) underscores its existentia—the latter, for Heidegger, is a “mine-ness” denoted as “presence-at-hand,” by which “entities are grasped in their Being.” But, what lies more primitively to presence-at-hand is “ready-to-hand,” or the average, “everydayness” of Dasein—it is a use-value of entities “in the world.” Dasein, then, allows entities to have Being “in the world”—when Being is “in the world,” it is translated beyond the “is-ness” of its everydayness and towards an “in-ness” extended in “the world.” Additionally, “Being-in-the-world” opens a possibility for “worldhood,” which, if one more carefully considers the original German, could be better represented as “worldliness.” Heidegger recognizes that Being-in-the-world is a “unitary phenomenon” composed of “in-the-world,” the every-case-ness of the way in which an entity is, and “Being-in” as such—all of which becomes facticities of Dasein.