Critical Thinking
Lecture 4: Informal fallacies（谬误）
It is easy for us to make mistakes in our reasoning becau we are easily affected by psychological emotions, social and political circumstances
(including our interests), and customs and public opinion, and complexity of reasoning itlf.
One of the purpos of this cour is to learn how to avoid mistakes or fallacies in reasoning.
The first thing we need to do is to identify fallacies.
1. Fallacies in general
A fallacy is a defect（缺陷）in an argument that consists in something other
than merely fal premis.
A fallacy that involves a mistake in reasoning is sometimes called a non
quitur (which, in Latin, means “it does not follow”).
Two kinds of fallacies: formal and informal特朗普演讲视频
If an argument is unsound or uncogent, then either it has one or more fal premis or it commits a fallacy, or both.
A formal fallacy is one that may be identified by merely examining the form or
structure of an argument. Fallacies of this kind are found only in deductive arguments.
Example of Formal Fallacies
If apes are intelligent, then apes can solve the puzzles.
Apes can solve the puzzles.
Therefore, apes are intelligent.
This is an invalid argument.
Formal fallacies are identified purely by analyzing the form.
It has the following form:
If P, then Q.
Q.
妙狗拯救圣诞节Therefore, P.
Counter example:
If it is a ro, then it is a flower.
It is a flower.
Therefore, it is a ro.
Informal fallacies are tho that can be detected（检测到）only by examining the content of the argument.
Examples of informal fallacies
A chess player is a person.
Therefore, a bad chess player is a bad person.
The Brooklyn Bridge is made of atoms.
Atoms are invisible.
Therefore, the Brooklyn Bridge is invisible.
Fallacies of Relevance（意义，关联）
The common feature to all the fallacies of relevance is that the premis are logically irrelevant to the conclusion, though they might be psychologically relevant.
1. Appeal to Force
The arguer tries to get his conclusion accepted by a person or persons by threatening that person or tho persons.
A girl to her boyfriend: “You should buy me a diamond necklace, otherwi I will
end our relationship.”
Secretary to boss: I derve a rai in salary for the coming year. After all, you know how friendly I a
m with your wife, and I’m sure you wouldn’t want her to find out what’s been going on between you and that xpot client of yours.
构成，提出
2. Appeal to Pity
Instead of providing the relevant evidence or reason, the arguer tries to evoke sympathy from the audience or the reader to get his conclusion accepted.
Taxpayer to judge: Your Honor, I admit that I declared thirteen children as dependents on my tax return, even though I have only two. But if you find me guilty of tax evasion, my reputation will be ruined. I’ll probably lo my job, my poor wife will not be able to have the operation that she desperately needs, and my kids will starve. Surely I am not guilty.
3. The Appeal to the People (Emotion)
The arguer tries to get the conclusion accepted by playing on the listeners’ or readers’ desire to be loved, esteemed, admired, valued, or accepted by others or included in a group of people.
Play on/upon 利用
There are direct and indirect appeal to the people.
Let us concentrate on indirect appeal.
The bandwagon argument风靡的活动，时尚
If you don’t do such and such, so and so, you will be left behind or out of the group.
Example:
鹬蚌相争翻译Of cour you want to buy Crest toothpaste, becau 90 percent of Americans brush with Crest.
The appeal to vanity 虚荣
If you do such and such, so and so, you will be admired, pursued or imitated. Example:
The Few, the Proud, the Marine.
The appeal to the snobbery势利态度
Similar to the appeal to vanity.
A Rolls-Royce [劳斯莱斯] is not for everyone. If you qualify as one of the lect
few, this distinguished classic may be en and driven at British Motor Cars, Ltd. (By appointment only, plea.)
Mother to child: You want to grow up and be just like Wonder Woman, don’t you? Then eat your liver and carrots.
4. Argument Against the Person (Argumentum Ad Hominem)
The arguer commits this fallacy if in his argument, he directs his attention to another arguer rather than the cond arguer’s argument or position.
There are three kinds of such fallacy: circumstantial, abusive and tu quoque
Ad hominem-abusive
The arguer verbally abus or attacks another arguer. (offensively or verbal abu)
Poet Allen Ginsberg has argued in favor of abolishing censorship of pornographic literature. But his a
rguments are nothing but trash. Ginsberg, you know, is a marijuana-smoking homoxual and a thoroughgoing advocate of the drug culture.
Ad hominem-circumstantial
普通话练习mp3The arguer discredit the opponent’s argum ent by alluding to certain circumstances about the opponent.
President George W. Bush argues that we should open up the Arctic National Wildlife Refuge for oil drilling. But Bush just wants to reward his rich cronies in the oil industry who got him elect ed. Thus, we can hardly take Bush’s argument riously.
Tu quoque (you too)
Child to parent: Your argument that I should stop stealing candy from the corner store is no good. You told me yourlf just a week ago that you, too, stole candy when you were a kid.
ksn
The judge has ruled that we are not paying our employees well enough. How can this be right when the judge’s own cretary doesn’t get paid well either?
5. Accident
One commits Accident if one misapplies (incorrectly applies) a general principle to a specific ca.
麦当娜的经典歌曲Dogs have four legs. Fido just had one of his legs amputated. So, Fido is not a dog any more.
6. Straw Man
This fallacy is committed when an arguer distorts歪曲an opponent’s对手，竞争者argument for the purpo of more easily attacking it.
Mr. Goldberg has argued against prayer in the public schools. Obviously Mr.
Goldberg advocates atheism. But atheism is what they ud to have in
Russia. Atheism leads to the suppression of all religions and the replacement
of God by an omnipotent state. Is that what we want for this country? I hardly think so. Clearly, Mr. Goldberg’s argument is nonn.
7. Missing the point (Irrelevant 不相关的Conclusion)
ecfThe premis are suppod to lead to one conclusion but a totally different conclusion is drawn.
Crimes of theft and robbery have been increasing at an alarming rate lately.
The conclusion is obvious: we must reinstate the death penalty immediately. Certainly Miss Malone will be a capable and efficient manager. She has a great figure, a gorgeous face, and tremendous poi, and she dress veryreferee
fashionably.
8. Red Herring
It is committed when the arguer diverts the attention of the reader or listener by changing the subject to a different but sometimes subtly related one.
The arguer tries to draw the audience or readers off right track and then draw a conclusion on a different issue.).
There is a good deal of talk the days about the need to eliminate pesticides from our fruits and vegetables. But many of the foods are esntial to our health. Carrots are an excellent source of vitamin A, broccoli is rich in iron, and oranges and grapefruits have lots of vitamin C.
We’ve all heard the argument that too much television is the reason our students can’t read and write. Yet, many of today’s TV shows are excellent.
“Seinfeld” explores important issues facing single people, “E.R.” pres ents
medical professionals in life-and-death situations, and “60 minutes” expos a great variety of scams and illegal practices. Today’s TV is just great!
偏离轨道
Fallacies of Weak Induction
Premis are relevant to the conclusion but not strong enough to draw the conclusion.
9. Appeal to Unqualified Authority
An argument commits such a fallacy if and only if the arguer appeals to the inappropriate authority that is not the expert in the subject at hand to prove the conclusion instead of relevant evidence or appropriate authority.
Pianist Ray Charles says that Sinclair paints are groovy. We can only conclude that Sinclair paints are very groovy indeed.
Appropriate正确的恰当的authority must meet at least two conditions:
(1) The expert on the subject.
(2) There is agreement among experts in that area.
嵌入式linux 培训“Why should I be moral?” must be one of the most important issues in ethics, becau professor Stephen Darwall says so, who is one of the leading
philosophers in ethics and there are no other moral philosophers哲学家who disagree with him.
In some areas such as politics, morals, and religion, there is no appropriatecasting什么意思
authority we can appeal to. For example,
Abortion (Homoxuality) is morally wrong becau according to the Bible, it is wrong.
10. Appeal to Ignorance
An argument commits this fallacy if and only if when the premis state that this statement must be true becau it has not been proved fal or it is fal
becau it has not been proved true.
Arguments are suppod to provide positive evidence. If something is incapable of being proved or disproved, we cannot u that thing to prove or disprove a conclusion.
People have been trying for centuries to provide conclusive evidence for the claims of astrology, and no one has ever succeeded. Therefore, we must conclude that astrology is a lot of nonn.
Converly,
People have been trying for centuries to disprove the claims of astrology, and no one has ever succeeded. Therefore, we must conclude that astrology is true.
Two exceptions
(1) If qualified rearchers investigate a certain phenomenon within their range
of experti and fail to find any evidence, then this arch can constitute
evidence for a conclusion.
Teams of scientists attempted over a number of decades to detect the existence of the luminiferous ether, and all failed to do so. Therefore, the luminiferous ether does not exist.
(2) If it is an issue of courtroom procedure:
Members of the jury, you have heard the procution prent its ca against the defendant. Nothing, however, has been proved beyond a reasonable doubt. Therefore, under the law, the defendant is not guilty.
No fallacy since “Nothing has been proved beyond a reasonable doubt” is what “not guilty” means in its legal n.
11. Hasty Generalization (Conver Accident)
This fallacy is commited when a general conclusion is drawn from a too small sample (a few cas) or a biad sample (not reprentative).
On our first date, George had his hands all over me, and I found it nearly impossible to keep him in h
is place. A week ago Tom gave me that stupid line about how, in order to prove my love, I had to spend the night with him. Men are all alike. All any of them wants is x.
12. Fal Cau
The connection between the premis and the conclusion depends on an imagined causal connection that does not exist.
Three types of fal cau: non causa pro causa (“not the cau for the cau”), “after this, therefore, becau of this” and oversimplified cau.
