辩证唯物主义认为否定之否定是自然界、人类社会和思维发展的普遍规律。反证法就是人们自觉不自觉地运用这一规律来证明数学命题的一种基本方法。以往人们一般总认为反证法是以形式逻辑学中的矛盾律和排中律为基础的。譬如要证明命题“若 A 则 B”,根据排中律,只需证反命题“若 A 则非 B”是 Dialectical materialism considers the negation of negation as a universal law of development of nature, human society and thinking. Defeating the law is that people consciously and unconsciously use this law to prove the mathematical proposition of a basic method. In the past, people generally believed that the law of proof was based on the law of contradiction and the rule of law in formal logic. For example, to prove the proposition “If A is B,” according to the law in the row, only the card contradiction “If A is not B” is