Sine qua non
A sine qua non (, Latin: [ˈsɪnɛ kʷaː ˈnoːn]) or condicio sine qua non (plural: condiciones sine quibus non) is an indispensable and essential action, condition, or ingredient. It was originally a Latin legal term for "[a condition] without which it could not be", "but for...", or "without which [there is] nothing." Also, "sine qua non causation" is the formal terminology for "but-for causation." == Origin and spread == As a Latin term, it occurs in the work of Boethius and originated in Aristotelian expressions.