On the basis of this more precise insight into the structure of λόγος, Aristotle succeeds in characterizing the preliminary status of Platonic dialectic. Aristotle accomplishes this characterization in connection with the mode of research called "first philosophy," which considers beings in their Being. In connection with the exposition of the idea of an original and first science of Being, Aristotle refers even to the dialecticians and sophists, insofar as he says that they too claim to be philosophers.4 This claim to philosophy means that their knowledge and their interest in knowledge are directed to the whole, the ὅλον, to the ἅπαντα, all beings, and not to a determinate being. In this consideration, Aristotle takes the fact that there are dialecticians and sophists, as inauthentic philosophers, to be proof that philosophy aims at the whole. It indeed aims at the whole, ὅλον, in a quite determined sense: not in the sense that the determinations of the content of all beings whatsoever would be enumerated, and the various sorts of beings would be recounted and the qualities of individual things tallied. On the contrary, philosophy aims at beings insofar as they are and only insofar as they are. Thus it is not concerned, as we would say, with the ontical, with beings themselves in such a way that it becomes utterly engrossed in them, but instead it is concerned with beings in such a manner that it addresses the ὄν as ὄν—the ὂν λεγόμενον ᾗ ὄν. Hence it addresses beings in such a way that they are simply addressed with regard to their Being and not according to any other respect. This idea of "onto-logy," of λέγειν, of the addressing of beings with regard to their Being, was exposed for the first time with complete acumen by Aristotle. In this connection he arrives at the delimitation of dialectic and sophistry by opposing them to this idea of a first philosophy. We want to make that clear, quite briefly and more concretely, with the aid of the exposition Aristotle offers in Book IV of the Metaphysics.
4. Met. IV, 2, 1004b17ff.