Bìránxìng hé ǒuránxìng shì zhéxué zhōng de yí duì gàiniàn.
Necessity and contingency are a pair of concepts in philosophy.
Tips
usage
性 turns adjectives into abstract nouns: 必然 "inevitable" gives 必然性, 可能 gives 可能性 "possibility". The opposite is 偶然性 "chance, contingency". The word belongs to essays and academic writing.
