Autor: Feser, Edward

Buch: Scholastic Metaphysics

Titel: Scholastic Metaphysics

Stichwort: Akt und Potenz 3; Verhältnis zw. A. u. P.;

Kurzinhalt:

Textausschnitt: 1.1.2 The relationship between act and potency

36b If act and potency are distinct features of a thing, we must still address the question of what kind of distinction we are talking about. For Scholastic writers commonly differentiate between real distinctions and logical distinctions, where the former reflect differences in extra-mental reality itself and the latter differences in our ways of thinking about extra-mental reality. Scotists add to this classification the notion of a formal distinction as something intermediate between a real and a logical distinction. Thomists regard the distinction between act and potency as a real distinction, while Scotists and Suarezians regard it as a formal distinction. We will return to this issue below. (Fs)

36c Thomists also differ with Scotists and Suarezians about whether anything other than potency limits act. Take the roundness of a certain rubber ball, which is actual, but in a limited way insofar as roundness as such is perfect roundness yet the ball’s roundness is not perfect (since there is always at least a slight imperfection in even the most carefully made ball), and insofar as roundness, which is of itself a universal, comes to be instantiated in this particular object and in that sense limited to a particular time and place. The Thomist position is that it is only potency which can ultimately account for these limitations on a thing’s actuality. Indeed, this is the second of the twenty-four Thomistic theses:

Because act is perfection, it is limited only by potency which is a capacity for perfection. Hence, a pure act in any order of being exists only as unlimited and unique; but wherever it (act) is finite and multiplied, there it unites in true composition with potency. (Wuellner 1956, p. 120)

37a In particular, it is the potency of rubber qua material substance to take on different forms that limits the roundness currently in it to being only an approximation of perfect roundness; matter as such lacks the fixity or determinacy to realize more than such an approximation. It is also matter which limits the roundness to this rather than that particular time and place; and this too reflects matter’s potency, insofar as a given parcel of matter is always potentially at some other point in time and space even if actually at this one. (Fs)

37b Scotists and Suarezians, by contrast, hold that the limitations of a thing’s actuality can be accounted for by reference to the thing’s cause. The ball’s roundness is imperfect because the ball’s cause put, as it were, only so much roundness into it; the roundness is limited to this particular time and place because that is when and where the ball’s cause put it into the ball. For the Thomist, however, such an extrinsic principle of limitation is possible only if there is an intrinsic principle — something in the limited thing itself by virtue of which its cause is able to limit its actuality — and this can only be potency. Hence the cause of the ball can put a limited degree of roundness into it precisely because the ball has the potency to be something other than perfectly round; and it can cause the roundness to be instantiated here and now rather than some other time and place precisely because the rubber which takes on that form has the potency to be at various times and places. (Cf. Clarke 1994; Phillips 1950, pp. 187-91; Renard 1946, pp. 30-39)

38a This dispute is closely related to the dispute over whether the distinction between act and potency is a real distinction, to which, again, we will return below; and to the dispute over whether the distinction between a thing’s essence and its existence is a real distinction, which will be addressed in chapter 4. (Fs)

38b Even those who regard the distinction between act and potency as real emphasize that act is prior to or more fundamental than potency in several crucial respects. For one thing, any potency is always defined in relation to act. For instance, a rubber ball’s potency for melting, becoming flat, etc. just is a potency for being actual in those ways — for being melted in act, flat in act, and so on. (Fs)

38c Second, a thing’s potencies are grounded in its actualities. It is because the ball is actually made of rubber rather than either granite or butter that it has a potency for melting at just the temperature it does rather than at some higher or lower temperature. (Fs)

38d Third, a potency can be actualized only by what is already actual. For instance, the ball’s potential flatness and squishiness cannot actualize themselves, precisely because they are merely potential rather than actual; and neither, for the same reason, can anything else that is merely potential be what actualizes them. If they are to be actualized, it can only be something already actual, like the heat of an oven, which actualizes them. This is one version of the Scholastic principle of causality, which will be examined in chapter 2. (Fs)

38e Finally, act is prior to potency insofar as while there can be nothing that is pure potency — since, if a thing were purely potential and in no way actual, it would not exist — there can be something which is pure act. The notion of that which is absolutely pure actuality or actus purus is the core of Scholastic philosophy’s conception of God, and its existence is the upshot of the key Scholastic arguments for God’s existence. (Cf. Feser 2009, chapter 3; Feser 2011)