What is Logic?
Definition from Wikipedia:
Logic (Ancient Greek: λογική; German: Logik; French: logique; English: logic; Italian, Spanish, Portuguese: logica), also known as reason, argumentation, inference, or deduction, is the philosophical study of valid inference [1]. Logic is used in most intelligent activities, but it is mainly regarded as a discipline in psychology, learning, philosophy, semantics, mathematics, inferential statistics, brain science, law, and computer science. Logic discusses the general forms that logical arguments take, which forms are valid, and the fallacies within them.
Logic itself refers to the thought process of inference and proof, while logic as a discipline studies “the principles and standards of valid inference and proof.” As a formal science, logic studies and classifies the structure of propositions and arguments through formal systems of inference and arguments in natural language.
Fundamental Principles of Logic
The Law of Identity
A thing is identical to itself; “self” cannot “not be self.” Specifically, in the same thought process, a concept must maintain its own identity. That is, the Law of Identity requires that in the same thought process, the meaning in which a concept is used must be maintained consistently throughout. The function of the Law of Identity is to maintain the certainty of thought. The Law of Identity does not mean that things are immutable, nor does it require thoughts to be forever unchanged. Its role in thinking is to ensure certainty. Only with certainty can thought correctly reflect the world, and can people engage in normal intellectual communication. There are two common logical errors that violate the Law of Identity: confusing concepts or equivocating, and shifting the topic or changing the subject. For example: Darwin’s theory of evolution states that humans evolved from apes. You are human, therefore you evolved from apes.
The Law of Non-Contradiction
Two contradictory propositions cannot both be true simultaneously; one must be true and the other false. A thing cannot simultaneously “be” and “not be.” It either is or it isn’t. The logical error of “self-contradiction” is specifically manifested in the following aspects:
First, contradictions between concepts.
“A square and round table” “A house that is not a house” “He is both tall and short”
Second, contradictions between judgments.
“The entire building is pitch black,” and at the same time saying, “There’s a room in the building with lights on.” “No one has ever entered,” and at the same time saying, “Those who have entered have never come out.”
Third, statements containing implicitly contradictory concepts or judgments.
“This junior high school student works in Beijing.” “This robot was produced naturally.”
The Law of Excluded Middle
Things can only be in one of two states: “is” or “is not”; there is no intermediate state. That is, either A or non-A must be true, rejecting ambiguity. This requires that in terms of concepts and judgments, between A and non-A, one must be true.
Violations of the Law of Excluded Middle often occur due to equivocation or adopting a fence-sitting attitude between “is” and “is not.”
Categorical Syllogism
In the logical system, the categorical syllogism is also what is commonly known as deductive reasoning. 1. All living things die. 2. All humans are living things. 3. Therefore, all humans die. In the example sentence, 1 is the major premise, 2 is the minor premise, and 3 is the conclusion. The truth of the conclusion is based on the truth of the premises and the connection between them. That is, the minor premise should be a subset of the major premise, otherwise, an erroneous inference will occur.
The form of a syllogism is as follows:
- Major Premise: All M are P
- Minor Premise: S is M
- Conclusion: S is P
This is widely used in mathematical logic, and the form should be understandable to everyone.
Logical Fallacies
Logical fallacies are logical errors that occur during the process of logical reasoning. These errors are sometimes uttered unconsciously, and sometimes deliberately created to deceive. These are often used by those with ulterior motives as sophistry. If one lacks the ability to identify logical fallacies, they might be misled, deceived, brainwashed, and find themselves in the absurd situation of being sold out and even helping to count the money. Most formal fallacies are relatively obvious because the containment relationship or the reasoning process is clearly incorrect. However, informal fallacies are often not easily detected. Many common sophistries are logical fallacies that people are familiar with but rarely realize.
Ad Hominem
Ad hominem is avoiding the topic of discussion and instead questioning the speaker’s identity, motives, or status. This fallacy is the lowest trick. For example, when there’s no logical argument, one resorts to personal attacks to lower the opponent’s standing, making onlookers believe the opponent has low moral standards and is untrustworthy. A very famous example is the dialogue between Zhuge Liang and Wang Lang, which from a logical perspective is an incorrect demonstration. Wang Lang said: “Sweeping across the six realms, enveloping the eight directions; the myriad people incline their hearts, and the four quarters admire virtue: this was not gained by power, but truly by the mandate of heaven.” This means that the Cao family’s天下 (empire/rule) was not seized by force, but rather the Liu family was without Dao, and Cao Cao saved the common people from suffering and relieved them from hardship. What is this? This is the mandate of heaven. You, Zhuge Liang, compare yourself to Guan Zhong and Le Yi; why can’t you see that the mandate of heaven is with Wei? The second layer of meaning is that the Wei Kingdom’s empire was not seized from the Han dynasty, but rather Emperor Xian of Han repeatedly gave it up and abdicated to the Cao family, imitating the ancient sages Yao and Shun’s abdication. If you don’t believe me, you can ask Emperor Xian of Han; he is still alive and well as Duke Shanyang. The conclusion is that the Wei Kingdom’s empire was obtained legitimately and legally, and your Shu Han is the chaotic rebel. Wang Lang’s words are well-reasoned and well-supported, no wonder Zhuge Liang was silent and the Shu army found them convincing; this is called convincing people with reason. Zhuge Liang could not refute the other party’s viewpoint, so he used the sophistry of ad hominem argument. “I thought that as an elder statesman of the Han dynasty, you would have profound insights; how could such vulgar words come from you!” By disparaging the opponent for betraying the Han dynasty and surrendering to Wei. In ancient times, this was considered disloyal.
Circular Reasoning
A mode of reasoning where the truth of the argument’s conclusion is ultimately supported by itself. For example: “Xiao Ming is guilty because he is guilty.”
“A: Xiao Ming is a musical prodigy because he understands music very well. B: How do you know Xiao Ming understands music very well? A: Because Xiao Ming is a musical prodigy.”
“A: How did the chicken come about? B: It hatched from an egg. A: How did the egg come about? B: It was laid by a chicken.”
“Xiao Ming: What is a pine tree? Xiao Hua: A pine tree is a tree that produces pine cones. Xiao Ming: What is a pine cone? Xiao Hua: A pine cone is a spherical fruit produced by a pine tree.”
Straw Man Fallacy
By changing the opponent’s argument to form a new viewpoint, and then vehemently refuting the new viewpoint, making onlookers believe that the new viewpoint is wrong, and thus mistakenly thinking that the original viewpoint is also wrong. Originally, the opponent was discussing A, but secretly changed it to B, and then by refuting B, made people think that A was also wrong. Example: A: “Letting children run around on the main road is very dangerous.” B: “It’s wrong to lock children in a room.” This is a misrepresentation, a typical straw man fallacy. Because not letting children run around on the main road and locking children in a room are two different issues and cannot be confused.
A: “I support the death penalty and oppose all alternatives. A murderer deserves to die, it’s natural law.” B: “Advocating for the death penalty is advocating for revenge, and revenge shouldn’t go too far. Justice is not a tool for revenge.”
A: “Do you support the legalization of sex work?” B: “Yes, I do.” A: “You’ve bought sex before then!”
Appeal to Fear
This tactic is mainly used to create an atmosphere of fear, thereby influencing the judgment of bystanders and making them believe the debater’s viewpoint.
A typical example is a missionary encountered in school. “Do you believe in God?” “No, I don’t.” “Then you’ll go to hell.”
Appeal to Tradition
Using traditional views to support one’s own viewpoint. However, in reality, traditional views are not necessarily correct views. And debaters who use this tactic often intentionally omit the argumentation for traditional views. Example: “Women should naturally take on the work of washing clothes and cooking. Look, traditionally in China, a woman’s duty is to assist her husband and educate her children.”
It’s already 2020, and some people are still using ancient ideas to restrict modern people, which is truly laughable.
Appeal to Faith
This type of fallacy uses faith to replace logic and evidence. Such people lack the ability to think; as long as it doesn’t meet their expectations, they become unreasonable. There’s no need to debate with such people, because faith does not require evidence, it’s a pure waste of time.
For example: Galileo: “The Earth is round.” Believer: “I believe the Bible, the Earth is flat, don’t try to fool me.”
Hasty Generalization
Using a few, individual examples to illustrate that a special case holds true in most situations, rather than proving one’s point through statistics. For example:
“Exercise is beneficial for physical and mental health and improves living standards.” “Look at so-and-so athlete, he died at only 20-something years old.”
Conclusion
Through the common explanations of concepts, everyone should now understand and be able to identify common logical fallacies. Now, here’s an interesting example discussing eggs. Try to find out which fallacies were used. Customer: This egg is really unpalatable. Egg Lover: The duck egg next door from the Jin family is even more unpalatable, why don’t you talk about that? (Tu quoque / Appeal to hypocrisy)
Customer: This egg is really unpalatable. Egg Lover: Damn it, all talk and no action, no constructive criticism. If you’re so capable, lay a delicious egg yourself! (Ad hominem / Appeal to ridicule)
Customer: This egg is really unpalatable. Egg Lover: Look at that chicken laying eggs on TV, it looks like such a diligent, brave, kind, and upright chicken! (Appeal to emotion / Ad populum)
Customer: This egg is really unpalatable. Egg Lover: It doesn’t matter if it’s not laid well, the important thing is that the egg looks good. (Red herring / Irrelevant conclusion)
Customer: This egg is really unpalatable. Egg Lover: You grew up eating this egg, what right do you have to say it’s unpalatable? (Ad hominem / Appeal to loyalty/tradition)
Customer: This egg is really unpalatable. Egg Lover: What’s your intention and purpose in saying that? (Ad hominem / Poisoning the well)
Customer: This egg is really unpalatable. Egg Lover: If you don’t like it, don’t eat it. Go eat Zhang San’s egg next door. (Ad baculum / Appeal to force or threat)
Customer: This egg is really unpalatable. Egg Lover: How much money did the chicken next door give you? You’re talking nonsense here? (Ad hominem / Poisoning the well)
Customer: This egg is really unpalatable. Egg Lover: No matter how unpalatable it is, it’s an egg laid by our own chicken. For that reason alone, you can’t say it’s unpalatable. (Appeal to loyalty / Appeal to emotion)
Customer: This egg is really unpalatable. Egg Lover: You say your own chicken’s egg is unpalatable, are you even from Li Village? (Ad populum / Appeal to tribalism)
Customer: This egg is really unpalatable. Egg Lover: Damn it, you idiot. Get out! You’re not welcome here! (Ad hominem / Abusive)
Customer: This egg is really unpalatable. Egg Lover: What does it matter to you? What’s the use of talking? You’d be better off making money in this time, why bother fussing?! (Red herring / Appeal to practicality)
Customer: This egg is really unpalatable. Egg Lover: Immature, psychologically dark, complaining even about unpalatable eggs. (Ad hominem / Attacking character)
Customer: This egg is really unpalatable. Egg Lover: This egg was spoiled by a small group of hens who couldn’t lay eggs, who instigated it. (Scapegoating / Appeal to conspiracy)
Customer: This egg is really unpalatable. Egg Lover: Our country’s eggs are unpalatable, but X country’s eggs are delicious? Traitor! (Ad hominem / Patriotism bias)
Customer: This egg is really unpalatable. Egg Lover: Our country’s eggs can already defeat X country’s duck eggs, as a citizen, I feel proud! (Appeal to pride / Nationalism)
Customer: This egg is really unpalatable. Egg Lover: The eggs laid by our motherland’s chickens, no matter how unpalatable, I will not dislike them! (Appeal to loyalty / Patriotism)
Customer: This egg is really unpalatable. Egg Lover: How dare you say our farm’s eggs are unpalatable? Whose side are you on? (Ad hominem / Questioning loyalty)
Customer: This egg is really unpalatable. Egg Lover: You pick up the bowl to eat the egg, and put down the chopsticks to curse the mother. Ungrateful, forgotten kindness, shameless! (Ad hominem / Abusive)
Customer: This egg is really unpalatable. Egg Lover: Unpalatable eggs are a small minority, the vast majority of eggs are good, you just happened to eat one. (Hasty generalization / Appeal to statistical anomaly)
Customer: This egg is really unpalatable. Egg Lover: This is a few lawless elements misleading customers! (Scapegoating / Appeal to conspiracy)
Customer: This egg is really unpalatable. Egg Lover: This is instigation with ulterior motives, what do you want to do? (Ad hominem / Threat)
Customer: This egg is really unpalatable. Egg Lover: This is unsubstantiated, I hope the media can report objectively. (Appeal to authority/media manipulation)
Customer: This egg is really unpalatable. Egg Lover: In my opinion, some people’s eggs are not good, our eggs are five times better! (Bandwagon / Appeal to popularity)
Customer: This egg is really unpalatable. Egg Lover: Be patient! We are in the early stages of raising chickens, we need to wait a while longer! (Appeal to patience / False hope)
Customer: This egg is really unpalatable. Egg Lover: We are building a chicken farm with our own characteristics, so our hens can lay eggs with our own characteristics! (Appeal to novelty / Empty rhetoric)
Customer: This egg is really unpalatable. Egg Lover: This unpalatable egg has nothing to do with the earthquake, earthquakes certainly kill people! (Red herring / Non sequitur)
Customer: This egg is really unpalatable. Egg Lover: If the egg isn’t unpalatable, will people not die from an earthquake? What if a few more die? (Appeal to worse evils / Dismissing the problem)
Customer: This egg is really unpalatable. Egg Lover: Go, Chinese chickens, go! (Appeal to nationalism / Empty slogan)
Customer: This egg is really unpalatable. Egg Lover: Given that the diner is making unreasonable complaints about the egg being unpalatable, we went to Beijing twice to persuade and counsel. (Appeal to authority / Bureaucracy)
Customer: This egg is really unpalatable. Egg Lover: If there are still diners appealing, we will be forced to use re-education through labor. (Ad baculum / Threat)
Customer: This egg is really unpalatable. Egg Lover: This is a recent rumor spread by someone with ulterior motives online. (Dismissing as rumor / Conspiracy theory)
Customer: This egg is really unpalatable. Egg Lover: You are a small number of people who don’t know the truth! How can an egg be unpalatable? (Appeal to ignorance / Gaslighting)
Customer: This egg is really unpalatable. Egg Lover: If you’re so capable, go eat chicken meat! (Red herring / Shifting the burden of proof)
Customer: This egg is really unpalatable. Egg Lover: No egg is perfect, so you have no right to criticize any egg! (Fallacy of perfection / Dismissal of criticism)
Customer: This egg is really unpalatable. Egg Lover: It’s much better than last year’s egg, and compared to a few hundred years ago, this egg has improved a lot! (Appeal to progress / False comparison)
Customer: This egg is really unpalatable. Egg Lover: Countless chicks sacrificed to let you eat this egg today! (Appeal to emotion / Guilt trip)
“Expert” Egg Lover Customer: This egg is really unpalatable. Egg Lover: The correct guidance is the blessing of our chicken farm, and the wrong guidance is the disaster of our chicken farm! (Appeal to authority / Dogmatism) Customer: This egg is really unpalatable. Egg Lover: Although the taste is a bit off, it is beneficial to our health. If we arbitrarily introduce an X country egg, our absorption system, stomach’s tolerance, and even the entire endocrine system might collapse. (Appeal to fear / Slippery slope)
“Baidu” (Chinese search engine, implying censorship/control) Customer: This egg is really unpalatable. Egg Lover: Due to well-known reasons, we are very sorry! (Euphemism / Evasion) Customer: [This user’s comment has been blocked by the administrator] Egg Lover: Told you to stop talking. See, now you don’t even have eggs to eat, right?! (Ad baculum / Censorship and punishment)