luó jí xué / zhōng / de / máo dùn lǜ / yāo qiú / yī gè / mìng tí / bù néng / tóng shí / wéi / zhēn / yòu / wéi / jiǎ逻辑学中的矛盾律要求一个命题不能同时为真又为假。The law of contradiction in logic requires that a proposition cannot be both true and false at the same time.