What is perception?
For Kant, perception is the process of the noumenal realm being sensed through the categories of intuition such that our phenomenal experience is always a “mere appearance” of the thing-in-itself. Although Kant had a different understanding of what “Reality” entailed, we can say that for Kant, perception is the experience of reality through a representational filter such that we can never gain access to reality. In other words, we are trapped behind our senses and phenomenal experience, while objectively valid, is “merely” an appearance of a reality that never shows-itself-as-itself. Kantian perception is thus representational.
For Heidegger, in contrast, perception is the process of intentionally directing-oneself-towards the noumenal realm without any sort of representational mediation. We can say that for Heidegger, perception is the experience of responding to how the thing-in-itself shows itself to us. In other words, perception is direct and nonrepresentational.
“To say that I am in the first place oriented towards sensations is all just pure theory. In conformity with its sense of direction, perception is directed toward a being that is extant. It intends this precisely as extant and knows nothing at all about sensations that it is apprehending” (Basic Problems 63)
“The statement that the comportments of the Dasein are intentional means that the mode of being of our own self, the Dasein, is essentially such that this being, so far as it is, is always already dwelling with the extant. The idea of a subject which has intentional experiences merely inside its own sphere and is not yet outside it but encapsulated within itself is an absurdity which misconstrues the basic ontological structure of the being that we ourselves are.” (BP 64).
However, if we leave the phenomenon of perception here, we are left clueless as to how this notion of “directing-towards” is accomplished. Does intentional comportment mean that perception is always veridical? Can we not be mistaken in our perception? Here, we must understand the phenomenon and the semblance.
The phenomenon is that which shows-itself. We have already seen that what shows-itself is the extant Earth, the thing-in-itself. This Earth existed as an extant environs long before humans existed. “Such a being, for example, nature, does not depend in its being – that and whether it is a being or not – on whether it is true, whether or not it is unveiled and encountered as unveiled for a Dasein” (BP 219). The Earth is the noumenal realm i.e. the planet as it is independently of our perception of it. For Heidegger, the phenomenal/noumenal distinction is collapsed not by placing our intentional comportment entirely within a subjective sphere, but rather, by eliminating the representational medium which blocks our access to the thing-in-itself through intentional perception.
“the intentional constitution of the Dasein’s comportments is precisely the ontological condition of the possibility of every and any transcendence…The Dasein, comports existingly toward the extant” (BP 65)
How is this possible? Through ambient light. The Earth is there without our perceiving it. So is ambient light. The light bounces around the environment, settles into stable overlapping arrays, and carries information regarding the environment in virtue of the light interacting with the environment as it gets reflected/absorbed. All we have to do is direct ourselves towards this information. The evolutionary reasons for doing so are enormous given that visual perception gives us unparalleled access to behaviorally useful information. It is no surprise that visual perceptual systems have evolved independently in separate species numerous times.
So, the Earth is showing-itself to us in virtue of ambient light. We are behaviorally directed towards this information and react to it in terms of a functional contexture of instrumentality. But to say that we act towards this light in an instrumental fashion is not to say that we are somehow encapsulated within a subjective sphere of readiness-to-hand such that we never have access to the thing-in-itself. On the contrary, we are always already surrounded and enveloped by the thing-in-itself in virtue of inhabiting a giant rock which floats around the sun in an elliptical orbit.
“Nevertheless, the walls [in a lecture hall] are already present even before we think them as objects. Much else also gives itself to us before any determining of it by thought. Much else – but how? Not as a jumbled heap of things but as an environs, a surroundings, which contains within itself a closed, intelligible contexture” (BP 163)
Okay, so that is the phenomenon: a directing-towards that which surrounds us. The directing-towards is essentially an uncovering of what’s-already-there. However, perception is not veridical. We do not perceive the Earth in its pure-presence-at-hand. We interpret Nature in terms of entities. This is our understanding of being. Thus, “[Entities] show themselves, but in the mode of semblance” (SZ 222). Semblance is the perception of what shows-itself (the Earth) as something it-is-not. The Earth is not naturally composed of chairs, tables, people, cats, etc. It is composed of energy. The human world is made up of chairs, tables, people, cats, etc. Thus, we operate within a realm of semblance wherein what shows-itself is perceived as something it is not. The power to interpret the world in terms of entities is that which establishes the phenomenon of Being with a capital B. This capacity is granted to us through language and predication for “language is the house of Being”.
However, Heidegger’s great advance over Kant is to claim that even though we operate within a “subjective” realm of readiness-to-hand and intepretation, there is no representational mediation between us and the ambient optic array. Quite simply, for Heidegger, there is never anything transcendentally lurking “behind” the phenomena.“Uncovering…brings the uncovering Dasein face to face with the entities themselves” (SZ 227, emphasis added). We directly perceive the Earth in terms of Worldliness. In conclusion,
“As surely as we can never comprehend absolutely the whole of beings in themselves we certainly do find ourselves stationed in the midst of beings that are revealed somehow as a whole. In the end as essential distinction prevails between comprehending the whole of beings in themselves and finding oneself in the midst of beings as a whole. The former is impossible in principle. The latter happens all the time in our existence.” (What is Metaphysics? Basic Writings pg 99)