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.
In essence, the distinction between Vorhandenheit and Zuhandenheit in Dasein‘s comportment to beings (Seiende) in its being-in-the-world allows the inscription of meaning onto what is pre-phenomenologically speaking an “absurd” array of things positioned spatio-temporally in the constant “worlding” (Welten) or environing that happens as Dasein goes about the business of its existence in the projection enabled by its potentiality-of-being (Seinkönnen). There is no stopping to all this until Dasein expires through death as the finality of its finitude on earth. The metabolism of the body in life is no match for the incessant demand on the inscription of meaning on to beings that Dasein‘s wakeful moments bring to itself. Consciousness in being-in-the-world involves the metaphysics of meaning. It is therefore the dynamic interplay of Vorhandenheit and Zuhandenheit that makes possible the social being of Dasein – to which, work, among many things such as play, feasting, gardening, etc. belongs. Zuhandenheit – as that fundamental mode of being of a non-Dasein which allows Dasein‘s access to it, primarily as a tool (Werkzeug) (although in an unideal Mitdasein, Dasein can indeed use one another as tools through manipulation and exploitation), opens up and structures the societal interrelations of multiple existents of Dasein (through Mitdasein), making possible our freedom from solipsism in a bewildered, depressive encounter with undefined Vorhandenheit, or brute existence. Zuhandenheit is the primordial “clearing of being” (Lichtung des Seins) in terms of Dasein‘s relational existence with one another and with the world as a whole, making hermeneutically possible the understanding of the whole überhaupt. Significantly, by way of Zuhandenheit Dasein is enabled to understand that beings (Seiende) are not mere occurrences in space. Instead the orientation of “zu” opens up the ever present possibilities of beings being interpreted as to their relevance and meaningfulness in Dasein‘s dwelling in the world. In this sense beings qua Zuhandenheit are not to be understood solely in terms of equipmentality or tool-being, but as a clearing of being where Dasein‘s comportment towards being qua beings comes to be. It is not that Dasein is the measure of all things; Zuhandenheit is. Zuhandenheit enables the world to be a Lebenswelt for Dasein, and not a mere sum total of occurrences. Because of this, Zuhandenheit introduces time into the world, whereby Dasein exists temporalised (gezeitigt) in temporality (Zeitlichkeit). Temporality, as the horizon of finitude of being, enables Dasein not only to be, but also to die – instead of merely ceasing to exist upon the exhaustion of its time on earth. Death is the measure of meaningfulness in existence in Lebenswelt. Thanks to death, Dasein cannot exist as mere occurrence in the spatiality of the world.
Zuhandenheit emancipates Dasein from a reductive misunderstanding of beings as mere objective presence. On the metaphysical level, Zuhandenheit does away with the vexing dualism between subject and object: Dasein‘s primordial comportment to being in its nearness to and association with beings (Seiende) is established upon the hermeneutics of ontological difference that allows for authenticity in its existential orientation to beings both Dasein and non-Dasein. Beings in the world do not take up a stance against Dasein, as in the traditional interpretation of an “object” as Gegenstand. Instead, Dasein and beings are existentially and inextricably bound up together in the totalising wholeness of the primordial phenomenon of understanding of being (Seinsverständnis). The irreducible Mitsein of beings in the world, therefore, is the fundamental way to describe the world, hence reality; to be is to be with (mit). Solipsism is an existential impossibility and an idle mental game. The metaphysical struggle between realism and idealism that has troubled Western thought for centuries now ceases at once in the coalescence of the understanding of being. It is by virtue of Zuhandenheit that we can understand that tool-being belongs with Mitsein, yet Mitsein is itself not tool-being. The phenomenology of acquisition of skills, participation in learning and working in cooperation highlights the fact that for tool-being to make sense and to be useful at all, the bringing together of this and that Dasein in the Mitdasein of learning and teaching is an essential first step. When this social process in Mitdasein is problematic, the relation of Dasein and the tool-being of a tool comes up against an obstacle, with the relation becoming unproductive – at least temporarily, or perhaps much longer. Zuhandenheit is disrupted.
Zuhandenheit throws into question the traditional metaphysical separation of theoria from praxis. As a philosophical alternative Zuhandenheit offers the new insight that theoria and praxis are interwoven through the metra (measure) of the understanding of being: distinction and difference are but the cleavage (Zerklüftung) in the sameness in being. Through Zuhandenheit we can get an appreciation of how ontology operates in the everyday world of doing and making by bringing thought and action together in the unity of being that the ontic-ontological distinction always refers back to under the aegis of ontological difference in fundamental ontology (Fundamentalontologie). While distinction withstands erasure, at the same time it affirms the primordial onefold (Einfalt) of being – the horizon against which all interpretations qua understanding of being take place in time. Zuhandenheit is the humanisation of Dasein in this universal interpretation.
Heidegger defines the being of Dasein as the potentiality-of-being (Seinkönnen) (Heidegger, 1996, p. 283) – that Dasein is a being which, for it to be, has its own being as its concern, which in turn is fundamentally determined by the existential structure of care (Sorge). As Heidegger explains in Being and time, care has the four structural moments of understanding, attunement, entanglement (falling prey) and discourse, with each having its own temporality (Heidegger, 1996, p. 309). In its projection upon the world, Dasein is always and already oriented towards Zuhandenheit as the primary access to the being of beings (Sein der Seienden) other than itself. This orientation also takes up a great part of Dasein‘s care for itself and others in its being-in-the-world. Interpreted on the everyday level, Dasein cares that “things” are working: literally and metaphorically. Things refer not only to tools, but also to relationships that shape Dasein.