Potentiality and actuality


In philosophy, potentiality and actuality are a pair of closely connected principles which Aristotle used to analyze motion, causality, ethics, and physiology in his Physics, Metaphysics, Nicomachean Ethics, and On the Soul.
The concept of potentiality, in this context, generally refers to any "possibility" that a thing can be said to have. Aristotle did not consider all possibilities the same, and emphasized the importance of those that become real of their own accord when conditions are right and nothing stops them. Actuality, in contrast to potentiality, is the motion, change or activity that represents an exercise or fulfillment of a possibility, when a possibility becomes real in the fullest sense. Both these concepts therefore reflect Aristotle's belief that events in nature are not all natural in a true sense. As he saw it, many things happen accidentally, and therefore not according to the natural purposes of things.
These concepts, in modified forms, remained very important into the Middle Ages, influencing the development of medieval theology in several ways. In modern times the dichotomy has gradually lost importance, as understandings of nature and deity have changed. However the terminology has also been adapted to new uses, as is most obvious in words like energy and dynamic. These were words first used in modern physics by the German scientist and philosopher, Gottfried Wilhelm Leibniz. More controversially, Aristotle's concept of entelechy retains influence on occasional calls for the use of "entelechy" in biology.

Potentiality

"Potentiality" and "potency" are translations of the Ancient Greek word dunamis. They refer especially to the way the word is used by Aristotle, as a concept contrasting with "actuality". The Latin translation of dunamis is potentia, which is the root of the English word "potential"; it is also sometimes used in English-language philosophical texts. In early modern philosophy, English authors like Hobbes and Locke used the English word power as their translation of Latin potentia.
Dunamis is an ordinary Greek word for possibility or capability. Depending on the context, it could be translated as 'potency', 'potential', 'capacity', 'ability', 'power', 'capability', 'strength', 'possibility', or 'force' and is the root of modern English words dynamic, dynamite, and dynamo.
In his philosophy, Aristotle distinguished two meanings of the word dunamis. According to his understanding of nature there was both a weak sense of potential, meaning simply that something "might chance to happen or not to happen", and a stronger sense, to indicate how something could be done well. For example, "sometimes we say that those who can merely take a walk, or speak, without doing it as well as they intended, cannot speak or walk." This stronger sense is mainly said of the potentials of living things, although it is also sometimes used for things like musical instruments.
Throughout his works, Aristotle clearly distinguishes things that are stable or persistent, which hold their own strong natural tendency to a specific type of change, from things that appear to occur by chance. He treats these as having a different and more real existence. "Natures which persist" are said by him to be one of the causes of all things, while natures that do not persist, "might often be slandered as not being at all by one who fixes his thinking sternly upon it as upon a criminal." The potencies which persist in a particular material are one way of describing "the nature itself" of that material, an innate source of motion and rest within that material. In terms of Aristotle's theory of four causes, a material's non-accidental potential is the material cause of the things that can come to be from that material, and one part of how we can understand the substance of any separate thing. According to Aristotle, when we refer to the nature of a thing, we are referring to the form or shape of a thing, which was already present as a potential, an innate tendency to change, in that material before it achieved that form. When things are most "fully at work" we can see more fully what kind of thing they really are.

Actuality

Actuality is often used to translate both energeia and entelecheia . Actuality comes from Latin and is a traditional translation, but its normal meaning in Latin is 'anything which is currently happening.'
The two words energeia and entelecheia were coined by Aristotle, and he stated that their meanings were intended to converge. In practice, most commentators and translators consider the two words to be interchangeable. They both refer to something being in its own type of action or at work, as all things are when they are real in the fullest sense, and not just potentially real. For example, "to be a rock is to strain to be at the center of the universe, and thus to be in motion unless constrained otherwise."
Energeia is a word based upon ἔργον, meaning 'work'. It is the source of the modern word energy but the term has evolved so much over the course of the history of science that reference to the modern term is not very helpful in understanding the original as used by Aristotle. It is difficult to translate his use of energeia into English with consistency. Joe Sachs renders it with the phrase "being-at-work" and says that "we might construct the word is-at-work-ness from Anglo-Saxon roots to translate energeia into English".
Aristotle says the word can be made clear by looking at examples rather than trying to find a definition. Two examples of energeiai in Aristotle's works are pleasure and happiness. Pleasure is an energeia of the human body and mind whereas happiness is more simply the energeia of a human being a human.
Kinesis, translated as movement, motion, or in some contexts change, is also explained by Aristotle as a particular type of energeia. See below.

Entelechy ()

Entelechy, in Greek entelécheia, was coined by Aristotle and transliterated in Latin as . According to :
Aristotle invents the word by combining entelēs with echein, while at the same time punning on endelecheia by inserting telos. This is a three-ring circus of a word, at the heart of everything in Aristotle's thinking, including the definition of motion.

Sachs therefore proposed a complex neologism of his own, "being-at-work-staying-the-same." Another translation in recent years is "being-at-an-end".
Entelecheia, as can be seen by its derivation, is a kind of completeness, whereas "the end and completion of any genuine being is its being-at-work". The entelecheia is a continuous being-at-work when something is doing its complete "work". For this reason, the meanings of the two words converge, and they both depend upon the idea that every thing's "thinghood" is a kind of work, or in other words a specific way of being in motion. All things that exist now, and not just potentially, are beings-at-work, and all of them have a tendency towards being-at-work in a particular way that would be their proper and "complete" way.
Sachs explains the convergence of energeia and entelecheia as follows, and uses the word actuality to describe the overlap between them:

Just as energeia extends to entelecheia because it is the activity which makes a thing what it is, entelecheia extends to energeia because it is the end or perfection which has being only in, through, and during activity.

Motion

Aristotle discusses motion in his Physics quite differently from modern science. Aristotle's definition of motion is closely connected to his actuality-potentiality distinction. Taken literally, Aristotle defines motion as the actuality of a "potentiality as such". What Aristotle meant however is the subject of several different interpretations. A major difficulty comes from the fact that the terms actuality and potentiality, linked in this definition, are normally understood within Aristotle as opposed to each other. On the other hand, the "as such" is important and is explained at length by Aristotle, giving examples of "potentiality as such". For example, the motion of building is the energeia of the dunamis of the building materials as building materials as opposed to anything else they might become, and this potential in the unbuilt materials is referred to by Aristotle as "the buildable". So the motion of building is the actualization of "the buildable" and not the actualization of a house as such, nor the actualization of any other possibility which the building materials might have had.
Building materials have different potentials.
One is that they can be built with.		Building is one motion that had been a potential in the building material.
So it is the energeia or putting into action, of the building materials as building materials.		A house is built, and no longer moving.

In an influential 1969 paper, Aryeh Kosman divided up previous attempts to explain Aristotle's definition into two types, criticised them, and then gave his own third interpretation. While this has not become a consensus, it has been described as having become "orthodox". This and similar more recent publications are the basis of the following summary.

1. The "process" interpretation

and associate this approach with W. D. Ross. points out that it was also the interpretation of Averroes and Maimonides.
This interpretation is, to use the words of Ross that "it is the passage to actuality that is kinesis" as opposed to any potentiality being an actuality.
Opponents argue that this interpretation requires Ross to assert that Aristotle actually used his own word entelecheia wrongly, or inconsistently, only within his definition, making it mean "actualization", which is in conflict with Aristotle's normal use of words. According to this explanation also can't account for the "as such" in Aristotle's definition.