Construct the basic framework of logic

Logic is the foundation of all disciplines, and it is like a tool to polish diamonds. Other disciplines, such as mathematics, psychology and economics, are all rough diamonds. Only by thoroughly understanding logic can we polish dazzling diamonds.

Below I will introduce how to cultivate my own logical framework from five aspects. Used to review the content of this Friday's minute business school.

From the following three laws of logical thinking, identity, law of contradiction and law of excluded middle. There are two main methodologies, syllogism (deduction) and inductive review.

? Keith, people have existed for millions of years, but you have not existed for millions of years, so you are not a person. As soon as we listen, there must be something wrong with this sentence. But where is the problem? Maybe we don't know. The above sentence mentioned two people. But these are two completely different concepts. People have existed for millions of years, and people here refer to the human population. And you are not alone. The people here refer to you as an individual. This is obviously wrong.

In view of this situation, logicians have set three laws of logic. The first rule, identity, is that two identical words appear in a sentence and must refer to the same concept. Otherwise the logic is not rigorous.

Please listen to the following. This product is an activity, buy one and get one free. I want to be quiet. Who is quiet? The above two statements are typical concepts of stealing. Buy one get one free refers to the goods you want to buy and the small gifts you give. And two are quiet, the first one is quiet. The second is the name of the person, quietly. ? Using the concept of stealing in good faith is humor. Malicious use of the concept of stealing is sophistry. In that case, both sides can only tell the chicken with the duck, which will only waste more time.

Law of contradiction, that is, the law of non-contradiction. Two mutually negative views can't be right. Take this year's festival as an example, no gifts, only melatonin. No gifts, why not take melatonin? This is obviously a contradiction.

What are the two mutually negative views? She is a woman, the negative is that she is not a woman. Not a man, maybe a eunuch. To deny success is to be unsuccessful. Not a failure. It may not be successful for the time being, but it will be successful in the future.

Application, how to identify contradictory logical fallacies. There are three points to note. First, identify the concept of contradiction. For example, one evening morning. A young old man. Second, contradictory judgments. For example, no one has ever entered this cave, and no one has ever come out.

No one has ever been there. Understandably, people who have been in have never come out, which is contradictory to those who have not been in. Third, paradox. What I said is false. This is a classic paradox. If this sentence is true, it is false.

If this sentence is false, it becomes true. To sum up, to abide by the law of contradiction, we should train the ability to identify contradictory concepts, contradictory judgments and paradoxes.

These are two contradictory views, one of which must be right. There is no intermediate state. Survival and destruction. There is no intermediate state. For example, what I did in this matter was both successful and unsuccessful. These are all against the law of the middle of exclusion.

Law of excluded middle is very important, but his son's reduction to absurdity is more famous. According to law of excluded middle, since there are two contradictory views, in this intermediate state, there must be one view that is correct, and neither view is correct. Then, as long as I prove that one of the two viewpoints is right, the other is definitely wrong.

In the classic case, Liu Yong thinks that speaking out will offend the dragon's face. Emperor Qianlong wrote two life and death paper balls for Liu Yong to grasp the paper. Liu Yong knew that both of them were dead. What shall we do? He used his quick wits to grab a paper cup and eat it. Since it's a lot of life and death, look at the rest of the paper pile and you will know which one you are eating. Sure enough, all that was left was a pile of dead paper. In this way, Liu Yong recovered his life. This is an example of making full use of reduction to absurdity. Life and death, one life and one death, there is no middle state.

How to make better use of reduction to absurdity in life? There are three steps: reverse design, returning to absurdity and retaining truth.

Title: Fortune tellers cannot predict the future. On the contrary, fortune tellers can predict the future. Paradoxically, since fortune tellers can predict the future, they will win the lottery in advance. But the reality is that they have a high probability of not winning. Save it. Fortune tellers can't predict the future.

Let's talk about two methods of logical reasoning.

. Concept, in short, is a kind of reasoning of "major premise, minor premise and conclusion". The basic logic is: if the whole thing is something, then a part of it must be something; If all of a thing is nothingness, then a part of it must also be nothingness. For example, Socrates' famous syllogism, the major premise: everyone will die; Minor premise: Socrates is human; Conclusion: So Socrates is mortal. This is very simple. Then please listen to the next question.

I love my country, so I smashed a Japanese car; Since I love my country, if you stop me from smashing it, you are a traitor; Treason is wrong, you are a traitor, so your point of view is wrong; Your view is wrong, and my view is different from yours, which further proves that my view is correct.

After listening, do you feel what kind of divine logic this is? A logical syllogism should abide by five basic principles. First, four mistakes. A syllogism can only have three basic concepts. If there are four, it must be wrong. In the above example, people have existed for millions of years; You haven't existed for millions of years. So you're not human. In this syllogism, there seem to be three basic concepts: man, a million years and you. However, because the two "people" before and after violated the "identity", they are different, and there are four concepts: human, million years, you and human body. This is obviously wrong.

Second, China has two gais. What do you mean by this project? Everyone will die. Socrates is a man. The "person" here, connecting the major premise and the minor premise, is the middle term. What is GAI? All China people, meaning all, are the concept of GAI, that is, they are fixed and unambiguous. A part of a person is not the concept of GAI, because it is also a part and can refer to different concepts. For example, some people in China like to eat Chili, while some people in Henan are from China, so people in Henan like to eat Chili. Henan people may be people who don't like Chili.

The third major item is expanded, and the minor item is expanded. For example, swans can fly, swans are birds, so birds can fly. That doesn't sound right. Ostriches can't fly. The premise in the above example is that swans are birds, and the conclusion is that all birds can fly. The conclusion is the whole, that is, the expansion of the event. Fourth, the premise is negative and the conclusion is not inevitable.

Fifth, if there is a premise, the conclusion must be negative. For example, people are not vegetation, philosophers are people, and philosophers are not vegetation. Birds lay eggs, but this animal doesn't lay eggs, so this animal is not a bird.

To sum up, syllogism is simply a kind of reasoning of "major premise, minor premise and conclusion". If you want to recognize sophistry at a glance, you need to pay attention to five basic principles of syllogism. Four mistakes, two gais in the middle. Expand big events, expand small events. The premise is negative and the conclusion is not inevitable. If there is a premise, the conclusion must be negative.

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Concept, extracting conjecture from phenomenon.

For example, there is a flock of turkeys on the farm, and the farmer comes to feed them at eleven o'clock every day. After nearly a year's observation, a scientist in Turkey announced that he had discovered a great universal law: "Every morning at eleven o'clock, food will arrive." On the morning of Thanksgiving, it announced the law to the turkeys, but the food didn't come at eleven o'clock that morning, so the farmer arrested them and killed them and turned them into food.

It may be wrong to extract guesses from phenomena. Then it needs to be proved to be correct through deduction. Make it a law. All the knowledge we have learned is from induction to conjecture, and then proved to be law through deduction.

For example, Newton's three laws. Wait, the laws of physics are all. How to train induction? This is the famous john stewart Mueller.

First, seek common ground. The second method of seeking difference. Third, public law. Fourth, political reform. Fifth, the residual method.

Induction is a method to infer the general from the special. Induction is to put forward conjecture and deduction from phenomena and prove that conjecture is a law. Everything we know begins with induction. But knowledge has boundaries, and we must be aware of the possibility beyond conjecture, that is, the black swan. Always in awe.

Finally, it is concluded that to construct the basic framework of logic, we must know the three laws of logic, namely, the law of identity, the law of contradiction and law of excluded middle. And there are two methodologies that must be familiar with, syllogism and induction. They complement each other and are indispensable. Logic is brain-burning, but it is the foundation of all subjects, so it is necessary to study it.