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Aristotle's metaphysics vs Heidegger's being

How exactly is Heidegger's question of being related to Aristotle's quest in the Metaphysics? Aristotle argues that all beings are related to substance (once he expands his notion of a genus to a pros hen way) and that all beings are related in so far as they have an essential nature; a form, actuality etc. He then links all these substances to their cause, the highest cause of all, the unmoved mover. What does Heidegger think about this approach? Does he think Aristotle is wrong?
gpt
Well, this is a very difficult question, and heavily depends upon how we interpret each of these thinkers. Heidegger writes volumes and volumes on Aristotle, who is perhaps one of his biggest influences. So this cannot be more than a rough sketch.

But to give you a basic picture, Heidegger thinks that philosophy has basically had the same theory of time since Aristotle's *Physics*. Although he spends some time considering this issue, there's no difference (for Heidegger) between Aristotelian and Augustinian time (the so-called "A-Theory" and "B-Theory"). Both understand Being in terms of *presence,* and interpret time in terms of this interpretation, understanding time as a series of "containers," a stretch of infinitely divisible moments.

So whether we think of time as an eternal present, or the future and past as really existing, Heidegger thinks that we only interpret them in terms of the "present." 

For Heidegger, time is *tensed*. So he doesn't understand the *past* as a "present that no longer is" or the future as "a present that is not yet," but understands the future as something "futural" and the past as something "historical." For Heidegger, the three ecstasies of time (past, present, and future) form a unified manifold, where each ecstasy involves a relation to the other two modes. In *Being and Time*, he stresses the primordiality of the *future*, arguing that (at least for Dasein), the past and present should be understood in terms of the futurality of the future. That's the point of the whole "being-toward-death" stuff; Heidegger's trying to show that Dasein can relate itself to a future event that cannot be experienced in the present, but dramatically transforms its entire existence. 

Heidegger interprets *ousia* (usually translated as "substance," although this translation is problematic) as "self-enclosed presence." This has some etymological support. So Aristotle, in Heidegger's reading, understands Being as the self-enclosed presence of an *eidos*. Such presence is, Heidegger thinks, implicitly understood in terms of present-moment time, as something that persists throughout a series of nows.

This involves interpreting Being according to only one mode of time, understanding them as self-enclosed presence in the present. This covers over, Heidegger thinks, the ecstatic temporality of beings, as well as the play of concealment/unconcealment that makes their presence possible.

So Heidegger doesn't think that Aristotle is "wrong," because Heidegger falls among a list of thinkers who thinks that every philosopher is basically right. However, he thinks that this interpretation of Being remains *incomplete*, specifically because it has certain presuppositions about time and presence. In early writings, Heidegger also raises the problem of the difference between a "who" and a "what," although this might be dropped in his post-war writings.

>He then links all these substances to their cause, the highest cause of all, the unmoved mover.

Heidegger sees this move as "ontotheology," which means that it grounds the Being of beings in general in a certain kind of Being (in Aristotle's case, the Being of motion) and then grounds beings as a whole in a highest being, namely the "unmoved mover," the source of all motion. Heidegger thinks that this approach covers over the difference between Being and beings, what he calls the "ontological difference." To put it very briefly, it's basically the idea that if "God *is* the cause of all beings," the "is" still remains unexplained. We cannot explain Being by tracing beings back to some highest being, because this highest being *is* also a being, and must be explained in terms of its Being. So insofar as the unmoved mover *exists* as a being among other beings, it cannot clarify the *meaning* (*Sinn*) of Being. 

At the same time, Heidegger sees ontotheology as an attempt to make beings as a whole "constantly present," insofar as they are held into place by an eternal being (thus continually secured as possible objects of our knowledge), rather than understood as occurring in time.