Sine qua non

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Sine qua non (/ˌsaɪni kweɪ ˈnɒn, ˌsɪni kwɑː ˈnoʊn/,^[1] Latin: [ˈsɪnɛ kʷaː ˈnoːn]) or conditio sine qua non (plural: conditiones 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."