post-structuralism See CONTINENTAL PHILOSOPHY,. LYOTARD , STRUCTURALIS. potency, for Aristotle, a kind of capacity that is a correlative of action. We require no instruction to grasp the difference between ‘X can do Y’ and ‘X is doing Y’, the latter meaning that the deed is actually being done. That an agent has a potency to do something is not a pure prediction so much as a generalization from past performance of individual or kind. Aristotle uses the example of a builder, meaning someone able to build, and then confronts the Megaric objection that the builder can be called a builder only when he actually builds. Clearly one who is doing something can do it, but Aristotle insists that the napping carpenter has the potency to hammer and saw. A potency based on an acquired skill like carpentry derives from the potency shared by those who acquire and those who do not acquire the skill. An unskilled worker can be said to be a builder ‘in potency,’ not in the sense that he has the skill and can employ it, but in the sense that he can acquire the skill. In both acquisition and employment, ‘potency’ refers to the actual – either the actual acquisition of the skill or its actual use. These correlatives emerged from Aristotle’s analysis of change and becoming. That which, from not having the skill, comes to have it is said to be ‘in potency’ to that skill. From not having a certain shape, wood comes to have a certain shape. In the shaped wood, a potency is actualized. Potency must not be identified with the unshaped, with what Aristotle calls privation. Privation is the negation of P in a subject capable of P. Parmenides’ identification of privation and potency, according to Aristotle, led him to deny change. How can not-P become P? It is the subject of not-P to which the change is attributed and which survives the change that is in potency to X. See also ARISTOTL. R.M.