This is sensational. Many people paid for it. Someone said, "Ah, strange, I heard that Napoleon had a big head. Why is this skull no different from ordinary people? "
The juggler explained, "Yes, but this is Napoleon's childhood skull." The spectators immediately relieved and exclaimed, "A child's head is so big!"
Is this a joke? It's still true. We can't prove it. However, the logic contained in this story is still worth thinking about. Why did the audience fall for it? Maybe they didn't seriously think about the juggler's excuse at all, maybe they did, but they lacked a little logical mind.
Napoleon is a world-famous hero. He didn't die in childhood. The juggler casually said that the exhibit was Napoleon's childhood skull, which meant that he made a judgment: "Napoleon died young." This implies that "there can be no world-famous great hero Napoleon".
After all, lies are not round.
As we all know, Napoleon died in St. Helena at the age of 52. The juggler casually said that "this is Napoleon's childhood skull", which is obviously a lie. In isolation, this sentence does not contain logical contradictions. Because he explained before that this is "the skull of Emperor Napoleon", which means that Napoleon died not in childhood, but in middle age, that is, after becoming emperor.
Therefore, we can say that the juggler not only affirmed that "Napoleon died in his early years", but also advocated that "Napoleon did not die in his early years", which violated the law of contradiction.
The content of the law of contradiction is that an idea and its negation cannot coexist in the same thinking process. Its morphological formula is: "A is not a". Where A stands for any concept or judgment, non-A is a negation of A, a concept with contradiction or opposition to A, and a judgment with contradiction or opposition to A. The semantic formula of the law of contradiction is: in the same thinking process, two contradictory concepts cannot be the same truth.
The formula of the law of contradiction says: A and non-A deny each other and cannot be true, at least one of them is false. Therefore, some logical works are also called the law of non-contradiction. The so-called mutual negation of the two ideas applies to two situations. Substituting any concept into a, the first case refers to the contradictory relationship between two concepts, such as "driver" and "non-driver", either one or the other; In the second case, the two concepts are opposite. For example, "advanced molecules" and "backward molecules" deny each other, but there is a third kind of people "intermediate molecules".
In terms of proposition or judgment, the law of contradiction requires that it is impossible to determine both the situation of something and the situation of something continuously in the same thinking process. For example, we can't say "Shanghai is a big city" and "Shanghai is not a big city".
Mistakes that violate the law of contradiction are often heard in daily life. Xinmin Evening News published a short article entitled "Freedom at a Price" on April 7, 2009:
Last Saturday, neighbor Ayan went to a barber shop on Guoshun East Road to wash her hair. The waiter washed her hair and promoted the service: "You just came today. Our shop is carrying out massage, so we can avoid the preferential activities of shampoo and hair dryer. Today is the last day. " A Yan was very moved: "Well, let me enjoy the massage, too." When checking out, Yan found that the price was wrong and asked the cashier. I didn't expect the other party to answer, "You made a mistake yourself. We charge a free price, understand? " Free and priced? This barber shop is "really talented"
A lady once boasted to her little sisters that her husband had big ears, a happy face and a lively mind, and was born to play the stock market, which made her earn a lot of money.
But not long after, the lady looked depressed and vented her troubles and regrets to her girlfriend. She said that she had said that her husband looked in the mirror incorrectly and looked like a fool. How is he qualified to play the stock market? It's not like a blind cat meets a dead mouse. I lost this time. I lost all my money.
Didn't these two words slap themselves? How similar it is to the butcher Hu in The Scholars.
Old boys wanted to go to the provincial capital to take part in the provincial examination, and borrowed a board fee from his father-in-law, butcher Hu. Butcher Hu spat hard and scolded him, saying, "Don't waste time! You just think you won a xianggong, so you want to eat swan meat ... these gentlemen are all satellites in the sky! Don't you see that the gentlemen of the Zhang family in the city are all rich in furniture and rich in every way? Like you, you should take a piss and look at yourself! No three no four, just want to eat swan fart! " But Jin Fan finally won the lottery quickly. At this time, the butcher wiped his face and said, "My good husband". "Every time I always say that my good husband has a high degree of education and looks good, and the lords like Zhang Fu and Zhou Fu on Liancheng's head are not as decent as my son-in-law."
The same Jin Fan is "sarcastic" at one moment and "polite" at the other, unlike a rich man with big ears. Butcher Hu's comments on appearance are inconsistent, even so. The author's description of Hu snobbery is due to the profound contradiction law.
The violation of the law of contradiction is characterized by fuzziness.
There was a man named Su Weidao in the Tang Dynasty who was the prime minister of Wu Zetian. This man is familiar with the anecdotes of the imperial court, and he writes good articles. However, he has been prime minister for several years, but he has accomplished nothing. The reason is that he is good at reading words and reading words, and he is a typical "unwilling officer". This "Feng" figure once told people about his knack of being an official: "You can't make a quick decision when dealing with things, or you will be punished if you make a mistake, as long as you catch both ends." At that time, people nicknamed him "Su Moling". "Edge" refers to the edge of the table, and there is no certain direction formed on the edge. It can refer to this end or that end, and it tastes like "stepping on two boats". The idiom "ambiguity" came into being here. The implication is that we can say this or that about two mutually negative thoughts, or we can say that we both affirm and deny the same thought. Any mistake that violates the law of contradiction is logically called ambiguity or contradiction.
Finding ambiguity, that is, finding logical contradictions, is a good way to refute the argument against the enemy. Because you can't justify yourself, how can you make people believe it?
A and B argue about "whether conscious action has a purpose", and B and A have different opinions. He said: "Conscious actions can have no purpose. I can raise my hand consciously and aimlessly. You see, I raise my hand now, although I don't need to do so. " B really raised his hand to prove his point. In this way, B proved the opposite fact. He raised his hand to prove that he can consciously complete an "aimless" action, that is, raise his hand purposefully. So, B made an ambiguous mistake.
For two contradictory propositions or judgments, the law of contradiction reveals that they must be false and cannot be true; Law of excluded middle revealed that there must be truth, but truth cannot be equated with fallacy.
Law of excluded middle's content is: In the same thinking process, one of the two contradictory viewpoints must be correct. Its formula is: "either one or not for a long time." Among them, A and non-A are contradictory concepts or judgments. A and non-A must be one of them, and no third party can choose.
Law of excluded middle's semantic formula is: In the same thinking process, two contradictory thoughts cannot be false.
Some people say that whales are mammals, while others say that whales are not mammals. If someone says they don't agree with the former view or the latter view, then we say that the latter view has made the mistake of "two noes" and violated law of excluded middle.
Law of excluded middle's formula is a form of selective judgment. A and non-A indicate that the selective limbs have been exhausted, and there is no third possibility. Therefore, law of excluded middle's logical feature is to exclude intermediate possibilities. In the face of two contradictory judgments, we must choose one of them, and we can't think that both are false. In two contradictory propositions, if one is known to be false, then the other is known to be true.
Mathematician smolin made up a logical reasoning problem according to the plot in Shakespeare's famous play The Merchant of Venice:
The heroine Portia said to the suitor, "Here are three boxes: a gold box, a silver box and a lead box. There is a sentence written on the nameplate of each box. Only one of these three sentences is true. Whoever can guess which box my portrait is put in can be my husband. " The gold box says "the portrait is in this box", the silver box says "the portrait is not in this box" and the lead box says "the portrait is not in the gold box". The suitor guessed right.
Here, the prosecutor used the method of excluding intermediate knowledge. The pursuer sees that a sentence written on the lead box and a sentence written on the gold box are mutually negative, which is two contradictory judgments. According to law of excluded middle, there must be a truth in two contradictory judgments. According to the meaning of the question, only one sentence is true, and this truth can only be judged in these two contradictions, so the sentence on the silver box is a lie. Since the words "the portrait is not in this box" on the silver box are false, it can be concluded that the portrait is in the silver box.
During the time when Sakyamuni Buddha lived in India, there were many schools of Samoan thought, one of which was called "Eel Slippery Theory". Some Samoans and Brahmins can't tell right from wrong and are as unpredictable as eels, because they are afraid of saying the wrong thing, questioning, or being slow and stupid. This is a typical example of going against law of excluded middle.
In our daily thinking, we seldom make the mistakes of "two noes" directly, but the mistakes that violate law of excluded middle are mostly in vague statements and prevarications. For example, when a family gave birth to a boy, relatives and friends came to congratulate him at the full moon. Those who say that their children will become big officials in the future will be rewarded; People who say that their children will get rich in the future take back a few good words; People who say their children will die in the future are beaten. Lu Xun commented with emotion in his essay "Weeds": Those who tell lies will be rewarded, and those who tell the truth will be beaten. If I were you, I would say, "Oh, hahaha, hahaha …" This is an irony of the world.
Law of excluded middle asked people to admit that one of the two contradictory judgments is true, which requires people to have certainty in their thoughts. Between right and wrong, truth and falsehood, we can't deny both. The "middle" excludes the "middle way" that does not actually exist. Therefore, some logical books call law of excluded middle "the law of impermissibility".
On the eve of nirvana, the Buddha preached four commandments to all monks: whenever a monk said that he was listening to the Buddha somewhere, some monks somewhere, some elders somewhere, and some elders somewhere, this is the law, this is the law, and this is the teacher's teaching. You should neither agree nor object, but remember the words and meanings clearly and check them with the law of harmony. If it doesn't conform to the sutra, you can say, "This is definitely not what the Buddha said. Someone ... remembered it wrong. " If it conforms to Confucian classics and laws, it can be said: "This is indeed what the Buddha said, and some people ... remember it clearly." Don't make a rash statement, tell it truthfully after you know it truthfully, which reflects the certainty of thinking. This is the same as the attitude of western logic towards complex interrogative sentences.
Law of excluded middle is suitable for contradictory judgment, but not for opposing judgment. There is also a "middle way" between opposing judgments.
There is a story in "Everything is wrong, and the foreign reserves say the lower left". Qi Huangong intends to appoint Guan Zhong as Guan Zhong, and let him be solely responsible for the internal and external affairs of the imperial court. Qi Huangong consulted the civil and military officials of the Qing Dynasty and agreed to stand on the left after entering the customs and on the right after entering the customs. There is a man named Dong Guoya "standing in the middle gate". Qi Huangong asked him why he was standing in the middle. Dong Guoya asked Qi Huangong, if you let him monopolize power, aren't you worried that he will usurp power in the future? Answer with "goodness", "it is to make discipline serve the internal treatment, and Guanzhong treat the external treatment with participation."
For Guan Zhong's arrangement, there are not only two options, but also a third option, so ministers have three positions to stand in accordingly. This does not violate law of excluded middle.
The straightforward judgment of formal logic on the same material tells us that opposites can be the same as truth, but not the same as falsehood, and contradictions can be the same as falsehood but not the same as truth. Under the relationship of opposites, we can infer truth from falsehood, but we can't infer falsehood from truth. There is at least one truth between "some people have psychic powers" and "some people have no psychic powers".
Identity, Law of Contradiction and law of excluded middle demand and guarantee the certainty and non-contradiction of thinking from different angles. The three formulas are actually equivalent.