Logic is a basic, instrumental, normative and universal science. People who haven't learned it will think that logic is a very profound knowledge, which is far from our life. But in fact, logic is often used in our daily life. For example, we often say "you have no logic", and this "logic" refers to the laws and rules of thinking, which is what we study in logic. Logic is widely used in real life, especially in debate, because the process of debate is realized by reasoning, and there is no reason without reasoning. If we can master logical reasoning, especially the blunt syllogism, we can greatly improve the argument and persuasiveness of the debate.

The outspoken syllogism is the most typical deductive reasoning, which was founded by Aristotle and is the most perfect and rigorous part of the traditional logic system. The outspoken syllogism consists of three outspoken propositions, two of which are prerequisites-major premise and minor premise, and the other is conclusion; The so-called "three paragraphs" refer to the major premise, minor premise and conclusion.

In many cases, a syllogism can't really draw a conclusion. In order to avoid common mistakes, people have formulated a series of rules to guide argumentation. Therefore, for any given standard syllogism, we can judge it by examining whether there is any violation of the rules.

The six rules of an outspoken syllogism are as follows:

First, avoid four items;

Second, under at least one premise, GAI；;

Third, in the conclusion, the item of GAI must also be Gai in the premise;

Fourth, avoid two negative premises;

5. If a premise is negative, then the conclusion must be negative;

Six, the premise of two full names can not draw special conclusions.

Among these six rules, violating any one rule is invalid, and obeying all the rules must be effective. In the debate, our argument should be reasoned step by step in strict accordance with syllogism, otherwise there will be loopholes for the debate to break through. In fact, there have been many debates that violate the rules in the history of China. At first glance, these inferences seem well-founded and unbreakable, but in fact they are logically flawed. Taking the famous logical problem "white horse is not a horse" as an example, Gong Sunlong thinks that "a horse is a horse, so life is also a shape; White, so life color also; Fate is not fate, so it says, "A white horse is not a horse. "Simply put,' horse' is a form, and' white' is a color. The shape and color are different, so a white horse is not a horse.

In this way, the logic that a white horse is not a horse seems impeccable, but in fact it violates the third rule mentioned above-in the conclusion, the item of GAI must also be the premise of GAI. We translated this sentence with syllogism: a dark horse is a horse, and no white horse is a dark horse, so no white horse is a horse. This syllogism is an improper GAI, because the conclusion is asserted for all horses, but the premise is not asserted for all horses, that is, the conclusion exceeds the premise. But in fact, the gatekeeper said that horses could not enter the city. Since the white horse is included in the horse, the white horse cannot enter the city. The debate that GongSunLong used here is really sophistry.

Also sophistry is the article "Under the Ugly Sun" in Mencius. Marco asked Mencius, "When you were in the State of Qi, the King of Qi gave you a hundred gold, but you didn't want it. When you were in Song State, the King of Song gave you seventy taels, but you wanted it. " In the snow, Xue Jun gave you fifty ounces, and you asked for it. If it is right for you not to accept it before, isn't it wrong for you to accept it later? If it's right for you to accept it later. So it was wrong not to accept it before? In short, Mencius, are you always wrong? "

In fact, there is a logical problem in this passage, because the situation in different countries is different, which Mencius pointed out and refuted the concept of stealing: "Everything is right. When I was in the Song Dynasty, I was going to travel far away. Isn't it wrong to send someone on a long trip? " I heard that the roads in the snow were unsafe. Xue Jun sent me money to buy weapons, and of course I accepted it! But in Qi, you have to give money for no reason. Didn't that buy me off? A gentleman cannot be bought by money. "

Mencius was right in his heart. He thought I was right. But logically speaking, accepting money for no reason means buying, so why not give money for no reason? In addition, Mencius here replaced the fact that Marco accepted gold with the value he should or should not accept.

For another example, Mo demonstrates the logical topic "Kill thieves without killing people": "Thieves are also human beings; There are many thieves and not many people; No thieves, no one. Xi Yi Ming? There are many thieves who do evil, and there are many people who don't do evil; If you don't want thieves, you don't want anyone. The world and * * * is it. If it is, it is' stealing, people also; Love thieves, not lovers; Do not love thieves, do not love others; It's not difficult to kill a thief, it's not difficult to kill. Mohist school thinks that the meaning of "thief" in the proposition of "thief, man also" is different from that in the proposition of "killing thief, not killing people", so it takes "yes and no" as the logical basis of the proposition of "killing thief, not killing people". However, "killing thieves" and "killing people" are compatible in extension. No matter what kind of person a thief is, its extension is included in the extension of "person", so it is logically untenable to kill a thief without killing him. However, although this statement is wrong, it only confuses the concept with examples, not the sophistry of stealing the concept.

Through these three classic topics, we can see that in fact, those debate geniuses in history are nothing more than good at drilling logical loopholes. As long as we sort out and straighten out according to the rules of outspoken syllogism, we can catch loopholes and refute them.

The outspoken syllogism is an important way of argument in logic, which is often used in debates at all times and in all countries. On the one hand, we should flexibly use syllogism to serve our arguments, on the other hand, we should understand the possible fallacies in syllogism and prevent the other party from using syllogism to refute our views.

References:

[1] Owen? Copika? Cohen, Cohen, Zhang Jianjun. Introduction to logic: version 1 1 [M]. Renmin University of China Press, 2007.

[2]? Fan Mingya. Comment on the undisguised syllogism analyzed by Aristotle [J]. Journal of Southwest Normal University (Humanities and Social Sciences Edition),1987 (S2):10/-109.

[3]? Zhang. A new explanation of Mohism's proposition of "killing thieves but not killing people" [J]. Chuanshan academic journal, 20 1 1.