Act (Greek ἐνέργεια / ἐντελέχεια, Latin actus) denotes the actualization, the being-actual of an entity. It is the counterpole to potency (δύναμις, potentia), which means being-possible, the not-yet-actualized. Together, act and potency constitute the fundamental principles of the reality of all that is.
The distinction goes back to Aristoteles (Metaphysics IX) and is systematically developed by Thomas von Aquin. Act has ontological priority over potency: possibility presupposes actuality, not the reverse. A seed has the potency to become an oak, but this potency is real only because the act of the seed exists.
For an understanding of the person, the act-potency distinction is of decisive importance. The personhood ontology distinguishes two levels:
- Prote Energeia (first actuality): substantial personhood itself — the act through which the person exists at all. This being is inalienable and bound to no condition.
- Deutera Energeia (second actuality): the actual operations of the person — thinking, willing, loving. These may fail to occur (in sleep, in a coma) without personhood being extinguished.
The empirical-functionalist concept of person confuses the second actuality with the first: it counts as a person only the one who actually performs acts of consciousness. The substance ontology shows that this confusion misses the being of the person.
Sources: Generated by querying the Personhood ontology.
Further sources:
- Aristotle: Metaphysics, Book IX (Θ). In: The Complete Works of Aristotle, ed. Jonathan Barnes, transl. W. D. Ross. Princeton: Princeton University Press, 1984.
- Thomas Aquinas: Summa Theologiae, I, q. 3, a. 1 (Whether God is a body) and I, q. 77, a. 1 (On the powers of the soul). Transl. Fathers of the English Dominican Province. New York: Benziger Bros., 1947.
- Thomas Aquinas: De potentia (On the Power of God), q. 1. Transl. English Dominican Fathers. London: Burns Oates & Washbourne, 1932.