Considered analogically and in its own right, act denotes perfection just as potency denotes imperfection. Hence, potency plays a determining, limiting role in relation to act. Thus we say that God is pure act, because He is not limited by any potency, while the created being is a mixture of potency and act. Since act in itself is said to denote perfection, it is not limited except by a principle distinct from itself, namely, potency; wherefore the axiom: actus non limitatur a seipso. Both potency and act should be considered as principles of being, not as beings themselves. It is also important not to confuse potency and act as principles in the structure of being with two successive stages in the development of a being, as when one speaks of being first in potency (in potentia ) and then in act (in actu ).
Kinds of Act. To make use of the following classification one must be aware of the ontological scope of its application. The notions of potency and act are basically analogical. Hence, what might perfectly fulfill the notion of act from one point of view might be considered as potency from another point of view, at the same time. Thus the form of a being is act in relation to the matter that it actuates, while the essence of that which is composed of matter and form, in its turn, is potency in regard to the esse that actuates it.
Act That Is Neither Received nor Receptive. This is pure act, subsistence act, which is neither received into a limiting potency nor susceptible of receiving an act superior to it.
Act That Is Received but Is Not Receptive. This is substantial existence or esse, limited by essence, that in turn, plays the role of limiting potency in its regard. Esse, as such, is not in its own turn susceptible of receiving an act in the substantial order that would be superior to it. What is composed of essence and esse, however, is said to be ordered to activity as to an accidental act that perfects an individual substance. Operation is also an act in this category, for it perfects the faculty and through it the individual in which it is received and from which it emanates. But it too, in itself and in its own right, is not ordered to a superior act.
Act That Is Receptive but Not Received. The separated form belongs to this classification. It is not received into quantitatively signed matter (signata quantitate ), which would otherwise make it some type of individual being, but it does receive an act to which it is ordained and which is its proper substantial esse. An act that is not received, inasmuch as it is pure form, is called "infinite" because it is not limited by matter. Yet it is "finite" in the order of existence since it is not esse subsistens, but has a finite mode of existing. This category of act has the role of being a limited potency to esse.
Act That Is Received and Receptive. This is the category of all forms received into a limiting principle, that in their turn, are ordained to a further act that perfects them. Such, for example, is the form of a composite being received in the limiting matter that it actuates, but that, together with this matter, is ordained to the act of the composite, namely, the substantial esse. The same applies to any accidental form that is act in relation to its subject but is also potency in relation to a superior act that perfects it. An example would be a faculty that perfects an individual but is ordained to operation as to a superior act that in turn perfects the individual.
Pure and Mixed Act. What has been said thus far leads to the distinction between pure act and mixed act (purus and non purus ). In itself the first is not received and limited, whereas the second is. Again one must specify the given context in stating whether an act is pure or not. In relation to esse, God alone is Pure Act. In the order of essence, separated forms, that is, beings that are not composed, can be called pure and infinite inasmuch as they are not limited by potency.
First and Second Act. First act is often opposed to second act (actus primus and actus secundus ). This usage designates either form or essence in relation to the esse that perfects them, or the individual in relation to the operation that perfects it. That which perfects as an ultimate actualization is called second act.
One can sum up the different kinds of act as follows: (1) motion, act of the changeable, (2) substantial or accidental form (faculty, habit), (3) esse (existence) and (4) operation. Each in its own way is act and as such conveys the notion of perfection. Substantial esse and operation are alone, strictly speaking, terminal acts and are not further receptive in their own proper order.
Historical Development. The notion of potency as opposed to act, and as uniquely definable by it, was introduced into philosophy by aristotle. He first used these notions in the Physics to explain change, which he defined as "the act of that which is in potency, precisely as such" (201a, 10). In the Metaphysics he introduced act and potency as general divisions of being (1045b 34). Here also he arrived at the notion of pure act (1071b, 20).
Scholastic Thought. St. thomas aquinas applied the notions of potency and act in a context to which Aristotle could not have given thought, that of the real distinction between essence and existence. Here the notions attain a level of ontological profundity never before known (see essence and existence). Potency and act are also basic to the Thomistic thesis on participation and to the notion of being proper to St. Thomas (see below).
With John duns scotus one finds an early attempt to introduce an entity, unknown to Aristotle and St. Thomas, intermediate between potency and act, that is, virtual act (actus virtualis ). Virtual act is that which without the agency of any extrinsic causality, reduces a being from potency to act. Thus it is the complete power to pass into act by itself; all being that possess it are self-moved. Wherefore, Scotus reasons, the inefficacy of Aristotle's attempt to prove that whatever is moved is moved by another; for Scotus, the fact that motion involves passage from potency to act is no proof of that. For arguments against the virtual act of Scotus, see Sylvester of Ferrara, Comm. in 1 C. gent., Leon. ed., c. 13, p. 35, nn. 6–7. Francisco suÁrez rejects the distinction between essence and existence as part of his refusal to use the principle of the limitation of act by potency to prove the real distinction. Suárez admits neither this distinction nor the Thomistic concept of being upon which it is based. Instead he attempts to base the fundamental distinction between God as infinite and creature as finite on the notions of ens a se and ens ab alio. But he does not perceive the ties that unite the thesis of the distinction between ens a se and ens ab alio with the distinction in the Thomistic tradition between pure act and created being that is necessarily composed of potency (essence) and act (existence). Finally, Suárez subscribes to the notion of virtual act, with the consequences inherent in it (confer Disp. Meta., disp. 29, sect. 1, n. 7, ed. Vives, 26:23).
Leibniz and Descartes. Gottfried leibniz is situated, consciously or not, in the line of Scotus and Suárez inasmuch as he employs the notion of "active force" and replaces the notion of potency with that of "impeded act." For Leibniz, forces are always active. If they appear to be at rest, it is because their activity is impeded.
René descartes' elimination of the notions of potency and act is part of his deliberate rejection of all ontology. He combines both scientific reasons (for example, the principle of inertia) and philosophical arguments to condemn the principle that whatever is moved is moved by another. His reasoning rests generally on his opposition to the notions of potency and act. In all this there is a conscious rejection, a reflective break with the world of the ancients and the Middle Ages, in which the notions of being, act and potency occupy a central place. The consequences of this break were destined to become immeasurable.
Modern and Contemporary Period. Little by little, the notion of act came to be employed in one of its many senses. The moderns designate activity by it, and more particularly, the free intellectual activity of self-proper to man. The metaphysics of act now becomes subjectivistic, and this phenomenon is realized most characteristically in such philosophies as those of hegel or gentile. The latter attacks Aristotle, gratuitously at that, for regarding act as static, as an object, whereas it is grasped interiorly by consciousness. Louis lavelle shows a different emphasis; while maintaining the interiorization of act, he views act in relation to being, potency and choice, and thus avoids the strictly idealistic viewpoint of Gentile.
Recent Thomism. Since the appearance of Aeterni Patris, there has been a revival of the classic doctrine of potency and act. At the same time, discussions relative to its interpretation, its role in the Thomistic synthesis, its value in itself and its applications have been encouraged. The same can be said for the principle actus non limitatur a seipso and the conclusions that can be drawn from it.
Outside of scholasticism, the analogical notions of potency and act have on the whole lost their significance. One cannot, without great equivocation, connect scholastic usage with what contemporary thinkers make of these notions. Regrettable though this may be, it is a fact that must be faced.
Act and Being. The first of all notions is that of being, not of act. Potency and act divide being as such. Also, being is defined as that which is either in potency or in act, and not as that which exists; whence, the definition: ens est id quod habet relationem ad essesive actualitatissive possibilitatis. With St. Thomas the notion of being is profoundly "existentialized" by the fact that for him esse is the act of acts, the most profound, intimate and formal element in being. Unless one reverts to "essentialism," being is inconceivable without this reference to esse. Thus the whole metaphysics of St. Thomas is founded upon the notion of being understood with explicit relation to esse as act. This notion is what enables him to argue to the real distinction of essence and existence in finite being.
Act and Participation. The problem of the one and the many is at the heart of metaphysics. As St. Thomas saw it, participation is in turn basic to the solution of the problem of the one and the many. Numerically multiplied and limited beings are possible because they are beings by participation. They are not instances of esse per se subsistens, which is necessarily unique (God), but of esse received into limiting potencies, that is, into essences. The notions of potency and act, Aristotelian in origin, enabled St. Thomas to systematize the doctrine of participation, of Platonic origin, into a conceptualization that is precise and free from equivocation. St. Thomas's stroke of genius consists in having united these two perspectives into a new and irreducible synthesis that profoundly transformed the elements it assimilated, thanks in no small part to his distinctive notion of esse as act.
This notion also gives an essential profundity to his metaphysics of causality. For St. Thomas, the efficient cause touches the esse rerum, allowing him to conceive of God as cause of this esse, and even its proper cause. Creatures merely confer esse as secondary causes under God's premotion (see premotion, physical). Thus God is not merely a final cause, moving by desire (as was taught by Aristotle), nor merely the first formal and exemplary cause (as for the Platonists). It is in these perspectives that one must locate the secunda via of St. Thomas.
Act and Change. Historically in Aristotle and psychologically in human consciousness, act and potency are linked with the perception of movement and with one's own activity. This includes continuous movement, substantial change and the personal operation that precedes any discovery. To be grasped intelligibly and without contradiction, change presupposes: (1) a point of departure—potency, (2) a point of arrival—act, and (3) the imperfect act (actus imperfectus ) between these— essentially act in relation to the prior potency, that of the point of departure and at the same time potency in relation to the perfect act (actus perfectus ) at the terminal point of the movement. Wherefore, the classical definition of motion as "the act of a being in potency precisely as such."
See Also: potency and act; potency; action and passion; entelechy; existence; form; pure act; human act; motion; participation.
Bibliography: c. a. hart, Thomistic Metaphysics: An Inquiry into the Act of Existing (Englewood Cliffs, N.J. 1959). h. reith, The Metaphysics of St. Thomas Aquinas (Milwaukee 1958). f. van steenberghen, Ontology, tr. m. flynn (New York 1952). a. fossati, Enciclopedia filosofica, 4 v. (Venice-Rome 1957) 1:464–475. a. smeets, Actus en potentie in de Metaphysica van Aristoteles (Conférences d'Histoire et de Philologie ser. 3.49, Louvain 1952). g. manser, Das Wesen des Thomismus (Thomistische Studien 5; 3d ed. Fribourg 1949). c. giacon, Atto e potenza (Brescia 1947). w. n. clarke, "The Limitation of Act by Potency," The New Scholasticism, 26 (1952) 167–194. j. d. robert, "Le Principe: Actus non limitatur nisi per potentiam subjectivam realiter distinctam," Revue philosophique de Louvain, 47 (1949) 44–70. g. gentile, Genesis and Structure of Society, tr. h. s. harris (Urbana 1960). l. lavelle, La Dialectique de l'éternel présent: de l'acte (Paris 1946).
[j. d. robert]
act / akt/ • v. [intr.] 1. take action; do something: they urged Washington to act. ∎ (act on) take action according to or in the light of: I shall certainly act on his suggestion. ∎ (act for) take action in order to bring about: one's ability to act for community change. ∎ (act for/on behalf of) represent (someone) on a contractual, legal, or paid basis: he chose an attorney to act for him. ∎ (act from/out of) be motivated by: you acted from greed. 2. behave in the way specified: the man who was acting suspiciously. ∎ (act as/like) behave in the manner of: try to act like civilized adults. 3. (act as) fulfill the function or serve the purpose of: they need volunteers to act as foster parents. ∎ have the effect of: a five-year sentence will act as a deterrent. 4. take effect; have a particular effect: bacteria act on proteins and sugar. 5. perform a fictional role in a play, movie, or television production: she acted in her first professional role at the age of six. ∎ [tr.] perform (a part or role). ∎ behave so as to appear to be; pretend to be: I acted dumb at first. ∎ [tr.] (act something out) perform a narrative as if it were a play: encouraging students to act out the stories. ∎ [tr.] (act something out) Psychoanalysis express repressed or unconscious feelings in overt behavior. • n. 1. a thing done; a deed: a criminal act. 2. [in sing.] a pretense: she was putting on an act and laughing a lot. ∎ a particular type of behavior or routine: he did his Sir Galahad act. 3. Law a written ordinance of Congress, or another legislative body; a statute: the act to abolish slavery. ∎ a document attesting a legal transaction. ∎ (often acts) dated the recorded decisions or proceedings of a committee or an academic body. 4. a main division of a play, ballet, or opera. ∎ a set performance: her one-woman poetry act. ∎ a performing group: a sisters act. PHRASES: act of God an instance of uncontrollable natural forces in operation (often used in insurance claims). catch someone in the act surprise someone in the process of doing something wrong: the thieves were caught in the act. clean up one's act behave in a more acceptable manner. get one's act together inf. organize oneself in the manner required in order to achieve something. in the act of in the process of: they photographed him in the act of reading other people's mail. read the Riot Actsee Riot Act.PHRASAL VERBS: act out misbehave, esp. when unhappy or stressed. act up (of a thing) fail to function properly. ∎ (of a person) misbehave. DERIVATIVES: act·a·bil·i·ty / ˌaktəˈbilitē/ n. (in sense 5 of the verb). act·a·ble adj. (in sense 5 of the verb).
Something done; usually, something done intentionally or voluntarily or with a purpose.
The term encompasses not only physical acts—such as turning on the water or purchasing a gun—but also refers to more intangible acts such as adopting a decree, edict, law, judgment, award, or determination. An act may be a private act, done by an individual managing his or her personal affairs, or it may be a public act, done by an official, a council, or a court. When a bill is favorably acted upon in the process of legislation, it becomes an act.
ACT • abbr. ∎ American College Test. ∎ Australian Capital Territory.