Autor: Feser, Edward

Buch: Scholastic Metaphysics

Titel: Scholastic Metaphysics

Stichwort: Akt und Potenz 2; Aristoteles vs. Parmenides, Zeno (Paradox d. Teile) u. Heraklit (dynamischer Monismus); Vielheit - Einheit; Grundargument Potenz u. Akt

Kurzinhalt: Parmenides denies that there can possibly be more than one being. For if a being A and a purportedly distinct being B really were distinct, there would have to be something to differentiate ... basic argument for the distinction between potency and act:

Textausschnitt: 34a The Eleatic and Heraclitean extremes vis-à-vis change and permanence are paralleled by similar extremes on the question of multiplicity versus unity. Parmenides denies that there can possibly be more than one being. For if a being A and a purportedly distinct being B really were distinct, there would have to be something to differentiate them. But since A and B both are, by hypothesis, beings, the only thing that could do so would be non-being; and non-being, since it is just nothingness, does not exist and thus cannot differentiate them. (Fs) (notabene)

34b Zeno reaches a similar conclusion via his paradox of parts. If there is more than one being, then either these multiple beings have size or they do not. If they do not, then since things of no size can, even when combined, never yield anything with size, it would follow that there is nothing of any size at all, which is absurd. But if these multiple beings do have size, then they are infinitely divisible and thus have an infinite number of parts. And if they have an infinite number of parts, then they must all be of infinite size, which is also absurd. So there cannot be more than one being. (Fs) (notabene)

34c The Heraclitean position, by contrast, when pushed to the extreme would entail that there is only multiplicity and no unity in the world, nothing to tie together the diverse objects of our experience. There is this particular thing we call “round,” that one, and a third one, but no one thing, roundness, that they all instantiate; there is this perceptual experience of what we call a “ball,” that one, and a third one, but no one thing, that ball itself, that these experiences are all experiences of, and no one subject, the perceiving self, which has the various perceptual experiences. (To be sure, Heraclitus himself adopted a kind of monism on which there is one thing, the world itself, which is the subject of endless change — a dynamic monism rather than the static monism of the Eleatics. Still, none of what J. L. Austin called the “middle-sized dry goods” of everyday experience could count as unified subjects on this view.) (Fs)

35a Once again the method of retorsion might be deployed against such views. If, as the Eleatics claim, there is in no sense more than one being, then how can the Eleatic so much as distinguish between himself and his interlocutor, or his premises and his conclusion? How can he distinguish between the reality that his philosophy is supposed to reveal to us and the false appearance of things that it is intended to dispel? If, as the Heraclitean claims, there is no unity to the things of ordinary experience but only multiplicity, then there can be no one self who abides through the stages of a chain of reasoning — in which case how can the Heraclitean ever validly draw a conclusion from his premises, as he needs to do in order to make his case? And how could he even state his thesis unless there were stable, recurring patterns — roundness, flatness, melting, etc. — in terms of which to characterize change or becoming? (Fs)

35b The distinction between act and potency can be applied to a critique of the Eleatics’ denial of multiplicity, as much as to a critique of their denial of change. Contra Parmenides, non-being or nothingness is not the only candidate for a principle by which two beings A and B could be differentiated. For despite their both being actual, they can yet be differentiated by reference to their potencies. Two balls A and B might both be actually round and red, but differ insofar as A is actually rolling while B is rolling only potentially, B is actually in the drawer while A is in the drawer only potentially, and so forth. Zeno, meanwhile, supposes that the infinite number of parts a thing with size has are all in it actually, when in fact they are in it only insofar as a thing and its parts could each potentially be divided and divided again. (Fs)

35c We have, then, the following basic argument for the distinction between potency and act: That change and permanence, multiplicity and unity, are all real features of the world cannot coherently be denied; but they can be real features of the world only if there is a distinction in things between what they are in act and what they are in potency; therefore there is a distinction to be made in things between what they are in act and what they are in potency. (Fs) (notabene)

36a To this basic argument, Scholastic philosophy of nature would add a consideration from the success of modern science. Science would be impossible if either the Eleatic position or its Heraclitean opposite were true. If Parmenides and Zeno were correct, there would be no world of distinct, changing things and events for the physicist, chemist, or biologist to study; and perceptual experience, which forms the evidential basis for modern science but which consists precisely in a series of distinct and changing perceptual episodes, would be entirely illusory. If the opposite, Heraclitean position were correct, there would be no stable, repeatable patterns for the scientist to uncover — no laws of physics, no periodic table of elements, no biological species — and thus no way to infer from the observed to the unobserved. On either of these views, the ontological and epistemological presuppositions of science would be undermined. Yet there is no way to avoid the Eleatic and Heraclitean extremes without affirming the distinction between act and potency. So we must affirm it given the success of science. (Fs)