The belief that Aristotle opposes potency (dunamis) to actuality (energeia or entelecheia) has gone untested. This essay defines and distinguishes forms of the Opposition Hypothesis—the Actualization, Privation, and Modal—examining the texts and arguments adduced to support them. Using Aristotle’s own account of opposition, the texts appear instead to show that potency and actuality are compatible, while arguments for their opposition produce intractable problems. Notably, Aristotle’s refutation of the Megarian Identity Hypothesis applies with equal or greater force to the Opposition Hypothesis. (...) For Aristotle, then, potency and actuality are compatible. (shrink)