Martin Heidegger (A.D.1889-1976) was born in Messkirch in south-west Germany. Heidegger's conception of Time is presented in his book, Sein und Zeit (Being and Time). The understanding of the meaning of being was a life-long desire of Heidegger, so it is not surprising that his approach to the understanding of Time is through being. In particular, the being he called Da-sein (human being). Heidegger's analysis of Time remains one of the most insightful.
Heidegger focused on the existential analysis of Da-sein because he believed that "All ontology, no matter how rich and tightly knit a system of categories it has at its disposal, remains fundamentally blind and perverts its innermost intent if it has not previously clarified the meaning of being sufficiently and grasped this clarification as its fundamental task." He posited that "fundamental ontology, from which alone all other ontologies can originate, must be sought in the existential analysis of Da-sein." Why? According to Heidegger, Da-sein takes priority in several ways over all other beings."
He identified three
(1) ontic: Da-sein is defined in its being by existence.
(2) ontological: Da-sein has the capacity to understand existence.
(3) ontic-ontological: by being and by its capacity to understand existence, Da-sein is the necessary condition for the "possibility of all ontologies." Heidegger considered essentia (the essence of Da-sein as a being) and existentia (the being of Da-sein) as the two fundamentals of Da-sein. He believed that objective presence, which is the traditional ontological meaning of existentia does not quite describe the being of Da-sein. He wrote: "We can avoid confusion by always using the interpretive expression 'objective presence' for the term 'existentia', and by attributing existence as a determination of being only to Da-sein...The essence of Da-sein lies in its existence. The characteristics to be found in this being are thus not objectively present 'attributes' of an objectively present being which has such and such an 'outward appearance,' but rather possible ways for it to be, and only this. The thatness of this being is primarily being. Thus the term 'Da-sein' which we use to designate this being does not express its what, as in the case of table, house, tree, but being."
Heidegger posited that "Da-sein is always its possibility, a possibility that is continual and expressed as an averageness of everydayness. A possibility with an existential structure. He wrote: "the average everydayness of Da-sein must not be understood as a mere 'aspect.' In it, too, and even in the mode of inauthenticity, the structure of existentiality lies a priori. In it, too, Da-sein is concerned with a particular mode of its being to which it is related in the way of average everydayness...All explications arising from an analytic of Da-sein are gained with a view towards its structure of existence." Heidegger called the characteristics of the being of Da-sein "existentials" which he differentiated from "categories," the characteristics of those beings which are not Da-sein. He asserted that "'existentials' and 'categories' are the two fundamental possibilities of the characteristic of being...Beings are a 'who' (existence) or else a 'what' (objective presence in the broadest sense). It is only in the clarified horizon of the question of being that we can treat the connection between the two modes of characteristics of being."
Heidegger believed that the fundamental existential structure that consittutes Da-sein, is Being-in-the-World,
a structure with many aspects, some of which are Being-with, Being a Self, and Being-in as Such. According to Heidegger, Being-in-the-World
"stands for a unified phenomenon" that must been seen as a whole with "constitutive structural factors." He identitied these factors as:
(1) In the world: which pertains to the ontological structure of the world and the idea of worldliness
(2) The being: which is in the world
(3) Being-in as Such: the unfolding of the inness of the being who is in the world. Heidegger posited that Being-in-the-World unravels in an everydayness of disclosedness that is manifested as Fursoge (taking care) and Besorgen (concern). The totality of which is Sorge (care), the being of Da-sein. "In Da-sein there is a constant 'fragmentariness' which finds its end in death." Heidegger described the being of Da-sein, Sorge (care), as the ontological equivalent of "temporality." In other words, he believed that temporality is the primordial meaning of Sorge (care), the being of Da-sein.
Da-sein, Sorge and Temporality are the three insaparable fundamentals of Heidegger's Sein und Zeit. Heidegger clothed Da-sein in Primordial Sorge and instituted Sorge in the triadic structure of Temporality. Heidegger described this triadic structure as: the "not-yet" which is the being-toward its ownmost potentiality of being, the future; the "being-together with", an on-going encounter of Da-sein and its surrounding world, the present; and the "having-been", an encounter that has passed by, the past. He wrote: "We call the unified phenomenon of the future that makes present in the process of having been temporality." Heidegger asserted that this temporality should be distanced from the common understanding of future, present and past, associated with clock time which he identified as "the vulgar understanding of time," that was derived from the everydayness of Da-sein. He wrote: "Da-sein expends itself primarily for itself as a being that is concerned about its being, whether explicitly or not...expending itself for the sake of itself, Da-sein 'uses itself up.' Using itself up, Da-sein uses itself, that is, its time. Using its time, it reckons with it... and develops a measurement of time...The 'time' initially found therein ontically becomes the basis for the development of the vulgar and traditional concept of time."
Peter Oye Sagay