Summary: Being and Time (page 10)

Heidegger briefly summarises this history of ontology as follows. The question 'What is being?' appears, as we have seen, in Plato and Aristotle. This ancient ontology is handed down to the Middle Ages where, uprooted and therefore deformed, it becomes the content of Scholastic philosophy—its most emblematic presentation is probably to be found in Suárez's Disputationes Metaphysicae. Finally, this uprooted Greek ontology ¹—which, in Scholasticism, is no more than a fixed doctrinal capital—is transmitted to us through Descartes and then Hegel (especially in his Logic).

In the history of ontology, has being ever been brought into relation with time, as Heidegger wishes to do?

This happens in Kant, more precisely in his doctrine of schematism, which we find in the Critique of Pure Reason.

In Kant's doctrine, the schema is the third, intermediate term that links intuition and concept and thereby makes knowledge possible:

It is clear that there must be a third term which must stand in a relation of homogeneity, on the one side with the category and on the other with the appearance, and so make possible the application of the former to the latter. This mediating representation must be pure (devoid of any empirical element) and yet, on the one hand, intellectual and, on the other, sensible. Such is the transcendental schema.

Now this doctrine of schematism—which remains deeply mysterious (This schematism of our understanding in regard to appearances and their mere form is an art hidden in the depths of the human soul, whose true procedures we shall hardly ever be able to divine from nature and lay open before our eyes)—is precisely what leads Kant in the direction of the dimension of temporality.

In Being and Time, Heidegger sets himself the task of examining the chapter on schematism and, from there, Kant's doctrine of time. But he states his conclusion in advance: Kant does not succeed in taking the decisive step: It was to remain forbidden to Kant to break open the problematic of temporality. This is because Kant neither poses the question of being nor that of Dasein.

Before analysing the various faculties of knowledge—sensibility, understanding, and so on—Kant should have undertaken some prior work: he ought to have provided a thematic ontology of Dasein, or, in Kantian terms, a prior ontological analysis of the subjectivity of the subject.

With Kant we come to understand how the different faculties of knowledge work and how they are articulated with one another, but we learn nothing about the one who possesses these faculties—the human being—and this, Heidegger insists, is the more fundamental, prior question.

In other words: in order simply to be in a position to ask the question 'What is knowledge?', we must first answer the question 'What is the human being?'. This is the step Kant neglected.

In fact, he merely takes over the Cartesian conception of the human being as we find it in the Meditations on First Philosophy: the human being as a thinking thing, res cogitans. But Heidegger showed in the Introduction to Phenomenological Research that Descartes leaves the mode of being of the res cogitans undetermined. In the Cartesian cogito—'I think, therefore I am', cogito ergo sum—what is missing is the meaning of the sum. I think, therefore I am—but what is it to be? The same reproach can be made to Descartes as to Kant: he omits the question of being in general.

Since he never confronts this question, Descartes merely—and unconsciously—carries forward the ontology conveyed by Scholastic tradition: medieval ontology. The human being appears, like other things, as a thing created by God, an ens creatum. But this determination in turn points back to the most ancient Greek ontology: created-being, in the broadest sense of what has been produced by something, is an essential structural moment of the ancient concept of being.

Let us recap. From Kant we are led back to Descartes, who in turn leads us back to medieval ontology, which ultimately derives from Greek ontology.

This is the 'destruction' of the history of ontology that Heidegger had previously called for: we trace the question of being back to its origin, and in so doing we 'rekindle' it, as one might rekindle an ember; we recover its meaning.

But this return to the source is not meant to close the question. The aim is not to claim that the ancient answer to the question of being provides the solution to the problem—but to establish a critical debate with ancient ontology.

What, then, are the characteristic features of this ancient conception of being?

Heidegger assigns a decisive role to the Aristotelian theory of substance and accident: it is on this distinction that the whole ontology is built.

From Aristotle onwards, substance—ousia—is regarded as the ultimate form of being, as opposed to accidents: ousia is taken to fix the meaning of being.

But ousia itself carries within it the notion of 'presence', as the term parousia shows—a word that would later designate the promised return of Christ among us at the end of time.

In this term being and time are brought into relation: the being is grasped in its being as 'presence', that is, it is understood in relation to a particular temporal mode – the present.

Thus, in Greek thought, one dimension of time is given precedence: the present.

Yet this Greek interpretation of being lacks something essential: an understanding of the fundamental ontological function of time. Time itself is treated as just another being among beings. Such a naïve conception cannot provide the ground for resolving the question of being, or even for properly formulating it.

Aristotle devotes the fourth book of the Physics to an analysis of time. These luminous pages, which have shaped every subsequent conception of time—including that of Bergson— cannot, in the light of what we have just seen, offer a satisfactory answer.

This is why any examination of the history of ontology can only be critical and must take the form of a 'destruction': Only when the destruction of the ontological tradition has been carried through does the question of being achieve its genuine concretion.

¹ Our translation. The references for the quotations are available in the book Heidegger: A Close Reading