Chapter 49 [Case Analysis] <The Salesmanship of a Weapons Merchant>

Han Fei, a thinker in the Warring States Period in my country, told a paradoxical fable: There was a merchant who sold spears and shields in the state of Chu. He picked up the shield and boasted that my shield was so strong that nothing could pierce it; What it can't pierce.At this time, someone nearby asked him: If you pierce your shield with your spear, what will happen?The man who sold spears and shields was left speechless. Why can't this Chu businessman answer the questions raised by others?The reason is that what he said about spears and shields cannot be true at the same time.For my shield has nothing to pierce it implies that my spear cannot pierce my shield; and the statement my spear has nothing it cannot pierce implies that my spear can pierce me shield.There is a contradictory relationship between the two judgments (single negation and singular affirmation) implied in these two sentences: if they cannot both be true, there must be a false one.According to the law of non-contradiction, if the former is believed to be true, the latter must be admitted to be false; if the latter is believed to be true, the former must be admitted to be false.Faced with such a choice, the braggart businessman could not answer.

It can be seen from this story that logical contradictions are often inherently related to human interests.The reason why this Chu man's remarks contradicted himself was because he only wanted to sell his stuff as soon as possible, so he ignored the basic logic.This is called Li Ling Zhi faint.