Lecture 6- fallacies of arguments 

by Marianne Talbot, university of Oxford 

 

A fallacy

Is an argument that looks like a good argument…

but, it is not good.

 

formal fallacy :

If it’s snowing, the mail will be late 

It is snowing 

Therefore, the mail will be late…

———————————————

So you cannot find any counterexample

valid good deductive argument

 

If it’s snowing, the mail will be late 

the mail will be late 

Therefore, it is snowing…  

———————————————-

You can find the consistence of the set of sentences when we set the counterexample

maybe somtimes the mail will be late because postmen struck not because of the weather.

So this is fallacy 

And looking at two example above, we can realize that change in some orders results in a deductive argument becoming a argument with fallacy.  

 


informal fallacy : Relevance / vacuity / clarity 

 

1. Fallacy of relevance :

# Citing in support of a conclusion something that is true but irrelevant (non-sequitur)

Example of non-sequitur :

EX1: Bill live in a large building. 

Therefore, his department is large.

 

EX2: Every year many people are supported through life by their religious belief, 

So their religious belief must be true.

 

PS: both of them are also invalid arguments 

There arguments work 

because people

1) don’t notice the irrelevance

and because

2) they are overly.

A) generous ( they are reluctant to point out the irrelevant )

B) proud ( they don’t want to admit they cannot see a connection )

3)These contradict the principle of charity 

The principle of charity— don’t assume someone was wrong before getting a conclusion 

your interlocutor silliness is less likely than my bad interpretation 

for example, 

{......You think not P is true, but I think P is true. 

We have irrelevant arguments

So why do you think not P is true

And you give your reasons, and I give my reasons….

Then coming out with a proper argument....principle of charity.....}  

 

Example of the principle of charity :

Two rats in a cage…

They both come from different cages 

In one of those cages, 

one of the rats was given an electric shock every time a sound was made. 

But the same sound was resulted in the other rat being given a food pellet 

Now

the experiment became, and they had been put into the same cage.

Then sounds happened.

One rat was going to rush and shaking into the corner of the cage waiting for an electric shock.

And the other one was going to rush up to the food bowl looking for a food pellet 

Comment :

These two rats both over-generalize 

 


# Attacking a person that makes the argument rather than argument that is made (ad hominem)

Example of ad hominem :

Nick griffin is leader of the BNP 

Therefore his claim that someone worry about immigration is rubbish.

 

Von Daniken’s book about ancient astronauts are worthless 

Because he is a convicted forger and embezzler 

 

PS: both of them are also invalid arguments 

the conclusions of two example can be either rubbish or treasure and either worthless or valuable 

 

Be careful to distinguish :

Ad hominem attacks

attacks on someone’s right to say something.

 

EX: Nick Griffin is a self-professed racist

      So you should take care when listening to his claims about immigration.  

{ This conclusion only provide a warning, 

  but didn’t claim about the truth of the argument. }

 

Ad hominem fallacy :

attacks on the truth of what someone says. 

 

EX: Nick griffin is leader of the BNP 

      Therefore his claim that someone worry about immigration is rubbish.

{ There is no relevance between premise and conclusion

and got only reason to reject what he say}

 

EX: there is coffee in the common room.

      Yes, I know why his is going to tell me that.

      Because he likes everyone else to go to the common room first.

      And then discover it’s actually been served upstair today 

      And he get all chocolate biscuits. 

{ It doesn’t bear the truth of what the conversation said

and you are casting a doubt on his rectitude

But it’s a good reason to doubt about wether coffee is in the room. }

 


2. Fallacy of vacuity :

# citing in support of a conclusion that vary conclusion ( circular arguments )

In a circular argument the conclusion IS one of the premises.

EX: all whale are mammals

      Therefore, all whale are mammals

Q: id this valid ?  Valid but no good 

 

All circular arguments are valid…

Because there cannot be any possible situation

 in which the premises are all true, and conclusion false

If the conclusion is one of the premises. 

 

# citing in support of a conclusion a premises that assume the conclusion ( question-begging )

.......distortion 

In a question-begging argument the conclusion is ASSUMED by one of the premises.

Begging the question :

 

It is always wrong to murder human beings

Capital punishment involve murdering human beings…..ASSUME (not according to the truth)

—————————————————

Capital punishment is wrong….ASSUME

 

Capital punishment is legal.

But murder is illegal, so you cannot put them at the sam site. 

The argument is not valid.

 

# offering an argument that cannot be questioned ( self-sealing )

Two weeks from today at 2:45 you are going to be doing exactly what your are doing 

 

We must respect all moral belief. 

Therefore, moral relativism is true….self-defeating

 

The global economy is controlled by Jews ( and any appearance to the contrary is the result of Jewish cleverness )

 

Some self-sealing arguments move back and forth from Interesting but false claims, 

all human being are selfish, 

true but vacuous claims : all human actions are prompted by human desires.

 

EX: Selifsh people always do what they want without consider others.

      Mother Teresa wouldn’t help people unless she wanted to…

      Well she did help people out of her duty , and help people as much as she can

      Yes, but she wanted to do her duty 

      I mean she wanted to do what she did 

     The only thing she did was what she wanted to do 

     So, she is selfish as everyone else

     You will find something being reversed by redefine the meaning of “selfish”

 

Three ways an argument can be self-sealing :

  1. it can invert ad hoc ways to dismiss criticism ( if my prediction didn’t work it is because there were negative vibes in the room )
  2. It can attack its critics as unable to see the benefit of the position ( you have been taken in by those clever Jews ) 
  3. It can redefine key words (it is selfish to always be doing just what you want to do )

 


3.Fallacy of clarity :

Vagueness ( fallacy of the heap ):

If you only have one penny you are not rich 

If you are not rich and I gave you one penny 

Then you still won’t be rich 

————————————

It doesn’t matter how many pennies I give you 

You won’t be rich.

 

The heap fallacy trades on the fact that many words are vague 

Because they admit of borderline cases 

Tall, fat , clever 

And the idea that a series of insignificant differences 

Cannot result in a significant difference 

 

Identify a way of reducing the vagueness of these premises :

John has a nice income.
→ John is the top of  the10th percentile of income earner

 

Cocaine is a dangerous drug 
→ cocaine is additive 

 

Mary is a clever woman 
→ Mary had got three degrees of PHD

 

Jane is a terrific tennis player 
Wimbledon Champion titles

 

Misusing borderline cases ( slippery slopes ) :

The slippery slope fallacy :

 

Human are rational 

Because they act for reasons 

Radiators turn themselves on when it’s cold 

—————————————

Radiators are rational

 

Slippery slope fallacy depends on the idea that we should not distinguish 

between things that are not significantly different 

And the belief that if A is not significantly from B 

And B is not significantly from C

Then A is not significantly from C

This is only true with something transitive  

 

trading on ambiguity ( question begging ) :

The fallacy of ambiguity :

Mary had a lamb ; he follow her to school 

——————————————-

Mary had a lamb ; then she had a little broccoli 

Because lamb (small goat / meat ), had ( own / eat ), little ( size / age )

 

Equivocation : light 

A feather is light 

What is light cannot be dark 

——————————

Therefore, a feather cannot be dark 

 

The three types of the ambiguity :

  1. Lexical ( I thought it was rum )
  2. Structural ( Bert was a fat stock breeder )
  3. Cross reference ( my wife’s cousin is engaging to her former husband )

 

Explain the ambiguities in the following sentences :

  1. No one like Oxford and Cambridge students (being there  VS. studying in there )
  2. Every nice girl loves a sailor ( a famous sailor VS. a person who she loves )—structural ab.
  3. Our shoes are guaranteed to give you a fit ( thin VS. suit )
  4. Irritating children should be banned ( irritating someone VS. being irritating )
  5. Why do swallows fly south for winter? ( different emphasis by the accent )

 

第六講在敘述整個論辯中看似不錯,實際上卻隱藏陷阱,然後依照二大法則來找到陷阱是啥,而二大法則就是『正式』跟『非正式』的,先來說明正式,為可以找到『反證』,那非正式裡面又分了三種,第ㄧ:相關,空洞,清晰。相關性就是把沒有關聯的東西硬連起來,大的建築物當中並不一定每間房間都大,這是一個謬誤,另一個是人生攻擊,對人不對事。那空洞又分三種,第一就是繞圈圈,視結論就是前提之一,第二,扭曲意義,黑的硬要說成白的,第三,霸王硬上鉤,我沒有要跟你辯論,我說的就是對的。最後一組來到清晰度,大概就是不要一語雙關拉,不要用形容詞啊,用具體數據,再來就是比較的參考最標在哪等等,以上就是謬誤的內容,而

我覺得在GRE考試策略比較用得上的應該就是非正式謬誤當中的第一組:相關性,因為很多考到weaken題型的大多會將八竿子打不著邊的選項選起來,而忘了考慮到相關性,所謂的弱化題型不是找到一個牛頭不對馬尾的選項,其實必須要考量到我們的『相關性』跟是否可以找到『反例』滿足此二條件,才能說是weaken題型的答案。

 

 

以上來自牛津大學教授上課筆記希望能幫上忙,喜歡,或是不喜歡還是有錯誤,歡迎留言指教,謝謝!! 

 


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