Actus Primus Actus Purus Actus et Potentia

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Actus Purus

A term employed in scholastic philosophy to express the absolute perfection of

God. In all finite beings we find actuality and potentiality, perfection and

imperfection. Primary matter, which is the basis of material substance, is a pure

potentiality. Moreover, change necessarily supposes a potential element, for it is

a transition from a state of potentiality to a state of actuality; and material things

undergo manifold changes in substance, quantity, quality, place, activity, etc.

Angels, since they are pure spirits, are subject to none of the changes that

depend on the material principle. Nevertheless, there is in them imperfection and

potentiality. Their existence is contingent. Their actions are successive, and are

distinct from the faculty of acting. The fact that all things have in themselves

some potentiality warrants the conclusion that there must exist a being, God,

from whom potentiality is wholly excluded, and who, therefore, is simply actuality

and perfection, Actus Purus.

It is true that in the same being the state of potentiality precedes that of

actuality; before being realized, a perfection must be capable of realization. But,

absolutely speaking, actuality precedes potentiality. For in order to change, a

thing must be acted upon, or actualized; change and potentiality presuppose,

therefore, a being which is in actu. This actuality, if mixed with potentiality,

presupposes another actuality, and so on, until we reach the Actus Purus. Thus

the existence of movement (in scholastic terminology, motus, any change)

points to the existence of a prime and immobile motor. Causality leads to the

conception of God as the unproduced cause. Contingent beings require a

necessary being. The limited perfection of creatures postulates the unlimited

perfection of the Creator. The direction of various activities towards the realization

of an order in the universe manifests a plan and a divine intelligence. When we

endeavour to account ultimately for the series of phenomena in the world, it is

necessary to place at the beginning of the series -- if the series be conceived as

finite in duration -- or above the series -- if it be conceived as eternal-a pure

actuality without which no explanation is possible. Thus at one extreme of reality

we find primary matter, a pure potentiality, without any specific perfection, and

having, on this account, a certain infinity (of indetermination). It needs to be

completed by a substantial form, but does not of itself, demand any one form

rather than another. At the other extreme is God, pure actuality, wholly

determined by the very fact that He is infinite in His perfection. Between these

extremes are the realities of the world, with various degrees of potentiality and

actuality.

So that God is not a becoming, as in some pantheistic systems, nor a being

whose infinite potentiality is gradually unfolded or evolved. But He possesses at

once all perfections. He is simultaneously all that He can be, infinitely real and

infinitely perfect. What we conceive as His attributes or His operations, are really

identical with His essence, and His essence includes essentially His existence.

For all intelligences except His own, God is incomprehensible and indefinable.

The nearest approach we can make to a definition is to call Him the Actus

Purus. It is the name God gives to Himself: "I am who am", i.e., I am the fullness

of being and of perfection.

ARISTOTLE, esp. "Metaphysics", Bk. XI (Berlin, ed. 1831); "Physics", Bks. VII, VIII; ST. THOMAS,

"Comment. In lib. VII, VIII Physic." And "in lib. XII Metaphysic." (XI of Berlin ed.); "Summa

theologica", esp. P. I. QQ. ii, iii, iv, etc., "Contra Gent." L. I, c. xiii, xvi, etc.; PIAT, "Dieu et la nature

d'apres Aristotle" in "Revue neo-scholastique", VIII, 1901, p. 167 (reproduced in his book "Aristotle",

L, II, c., ii Paris, 1903); WATSON, "The Metaphysic of Aristotle", IV-"The divine Reason", in "Philos.

Rev." VII (1898), p. 341.

C .A. Dubray

Transcribed by John Looby

Dedicated to Msgr. Harold J. Martin of Canton, NY

The Catholic Encyclopedia, Volume I

Nihil Obstat, March 1, 1907. Remy Lafort, S.T.D., Censor

Imprimatur. +John Cardinal Farley, Archbishop of New York

The Catholic Encyclopedia: NewAdvent.org

Actus primus

A technical expression used in scholastic philosophy. Actus means

determination, complement, perfection. In every being there are many actualities,

and these are subordinated. Thus existence supposes essence; power supposes

existence; action supposes faculty. The first actuality (actus primus) begins a

series; it supposes no other actuality preceding it in the same series, but calls

for a further complement, namely, the second actuality (actus secundus). But as

the same reality may be called "actuality" when viewed in the light of what

precedes, and "potentiality" when viewed in the light of what follows (see ACTUS

ET POTENTIA), the meaning of the term "first actuality" may vary according to

the view one takes, and the point where the series is made to begin. Primary

matter (see MATTER AND FORM) is a pure potentiality, and the substantial form

is its first determination, its first actuality. The complete substance constituted

by these two principles receives further deternimations, which are, in that

respect, second actualities. Yet these may also be conceived as first actualities.

Thus the extensive quantity of a substance is a first actuality when compared to

the shape. Power is a first actuality when compared to action. And this is the

most frequent application of the terms actus primus and actus secundus. The

former is the faculty; the latter, the exercise, or function. To see in actu primo

simply means to have the sense of vision; to see in actu secundo is to actually

perform acts of vision. The modern distinction of potential and kinetic energy

might serve as another illustration: the loaded gun, or the engine with steam up

represent first actualities; the bullet speeding to the mark, the engine flying over

the rails, represent second actualities.

C .A. Dubray

Transcribed by Sheelagh Donaldson

In honor of Mabel Erckert Donaldson

The Catholic Encyclopedia, Volume I

Nihil Obstat, March 1, 1907. Remy Lafort, S.T.D., Censor

Imprimatur. +John Cardinal Farley, Archbishop of New York

The Catholic Encyclopedia: NewAdvent.org

Actus et Potentia

A technical expression in scholastic phraseology.

I. The terms actus and potentia were used by the scholastics to translate

Aristotle's energeia or entelecheia, and dynamis. There is no single word in

English that would be an exact rendering of either. Act, action, actuality,

perfection, determination express the various meanings of actus; potency,

potentiality, power, capacity, those of potentia. In general, potentia means an

aptitude to change, to act or to be acted upon, to give or to receive some new

determination. Actus means the fulfilment of such a capacity. So, potentia

always refers to something future, which at present exists only as a germ to be

evolved; actus denotes the corresponding complete reality. In a word, potentia is

the determinable being, actus the determined being. The term actus, therefore,

has a much greater extension than act or operation. Every operation is an actus,

because it is the complement of a power; but all other perfections and

determinations, whatever be their nature, are also actus. On the other hand, the

being in potentiâ is not to be identified with the possible being. The latter belongs

to the logical order; it is a notion whose elements involve no contradiction. The

former belongs to the real order; it exists in a subject which, though

undetermined, is capable of determination. Potentia is more than a mere

statement of futurity, which has reference to time only; it implies a positive

aptitude to be realized in the future. It would also be a mistake to identify the

scholastic actus and potentia with the actual and potential energy of physics.

These terms apply only to material substances, and are exclusively dynamic;

they signify the capacity for doing work, or the actual performing of work. The

scholastic terms apply to all, even spiritual, beings, and refer to any reality which

they possess or can acquire. The Aristotelian "energy" (actus) as such, i.e.,

considered as actuality, can never be potential, these two terms being opposed

to each other. Actuality and potentiality are mutually exclusive, since one means

the presence, and the other the absence, of the same determination. Yet, in all

beings except God (see Actus Purus) there is a combination of actuality and

potentiality; they possess some determinations and are capable of acquiring

others. Moreover, the same reality may be considered as actuality or potentiality,

according as we take a retrospective or a prospective point of view. In man, skill

and science are actualities if we compare them to human nature, which they

presuppose. But if we compare them to the actions themselves, or to the actual

recall of acquired knowledge to consciousness, they are powers, or potentiae. If

we keep the same point of view, it is impossible for the same thing to be at the

same time in actu and in potentiâ with regard to the same determination.

Aristotle and St. Thomas explain this theory by many illustrations, one of which

will suffice. The statue exists potentially in the block of marble, because marble

has an aptitude to receive the shape of a statue. This aptitude is something real

in the marble, since many other substances are deprived of it. It is a receptive

potentiality. With regard to the same statue, the sculptor has the power, by his

action, to carve the marble into the form of a statue. His is an active power, a real

skill or ability which is lacking in many other persons. In order to have the actual

statue (actus), it is necessary for the sculptor to exercise (actus) his real skill

(potentia) on a substance which is not yet a statue, but which has a real aptitude

(potentia) to become one. I can form no idea either of the marble's potentiality or

of the sculptor's skill unless I first know what is meant by an actual statue. In the

same manner, the man born blind is unable to understand what is meant by the

faculty of vision. In general, potentia has no meaning, and cannot be defined

except through the corresponding actus.

II. The distinction between potentia and actus is at the basis of, and pervades,

the whole scholastic system of philosophy and theology. Whatever is

determinable is considered as potential with regard to the actual determination.

Genus and species, subject and predicate, quantity and shape, child and adult,

matter and form of the sacraments, etc., are examples of potentiality and

actuality. Here we must confine ourselves to the fundamental applications in

metaphysics and in psychology. (1) In metaphysics the distinction runs through

the ten Aristotelian categories. All being, whether substance or accident, is

either in actu or in potentiâ. The essence of creatures is a potentiality with regard

to their existence. Material substances are composed of primary matter and

substantial form (see Matter and Form), matter being a pure potentiality, i.e.,

wholly undetermined, and form being the first determination given to matter.

Efficient causality is also an application of potentiality and actuality; the cause,

when at rest, remains able to act. Change is a transition from the state of

potentiality to that of actuality. Generation, growth, and evolution suppose a

capacity which becomes fulfilled. (2) In psychology special emphasis is laid on

the reality of the potentiae, or faculties, and their distinction both from the soul

and from their operations. External senses are determined or actualized by an

external stimulus (see Species), which gives them the determination necessary

to the act of perception. The internal senses (sensus communis, phantasia,

memoria, aestimativa) depend on external sensations for their exercise. Memory

and imagination preserve in potentiâ traces of past impressions, and when the

proper conditions are verified the image becomes actual. We have no innate

ideas, but in the beginning human intelligence is simply a power to acquire

ideas. By its operation, the active power of the intellect (intellectus agens) forms

the species intelligibilis or the determination necessary to the intelligence

(intellectus possibilis) for its cognitive act. All tendency and desire is actualized

by some good which one strives to acquire. In rational psychology man is

conceived as one substantial being, composed of body and soul, or matter and

form, united as potentia and actus.

There is a tendency today in nearly all the sciences towards "actuality" theories.

But, if analyzed carefully, such theories will necessarily yield potential elements.

In all things we find capacities for further development and evolution, forces and

aptitudes which come to be utilized little by little. In scholastic terminology these

are now real, but not actual. They exist only as potentiae, which, to manifest

themselves, await the proper actualization.

C. A. Dubray

Transcribed by Bob Knippenberg

The Catholic Encyclopedia, Volume I

Nihil Obstat, March 1, 1907. Remy Lafort, S.T.D., Censor

Imprimatur. +John Cardinal Farley, Archbishop of New York

The Catholic Encyclopedia: NewAdvent.org