Informal Fallacies

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Informal Fallacies

• Chapter 5

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Formal vs. Informal fallacy

• Formal
• The logic is wrong Not sound
• Bad reason fallacy error in the way the argument
  is structured or built (invalid set up, 9 rules)
• Doesn't force a true conclusion with all true
  premise
• Informal
• Mask Man fallacy subjective, emotional language
  in propositions.
• The masked man is Mr. Hyde. TThe witness
  believes the masked man committed the crime.
  TTherefore, Mr. Hyde committed the crime. F

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Informal Fallacy

• Error with the content of arguments
• Words chosen
• Phrases chosen
• How we express our arguments
• Can be formally valid, built logically
• Allows you to notice irrational thought
• Informal fallacies are defects found in the
  content of the argument, which could be inductive
  or deductive.

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Major types of informal fallacies

• Fallacies of ambiguity (Cleaner)
• The words or phrases need to be defined- or are
  vague- or change meaning in the argument
• Fallacies of relevance (Connection)
• The considerations that are offered in support of
  the conclusion are irrelevant to determining
  whether that conclusion is true. It makes it
  possible for the premises to all be true and
  conclusion to be false.
• Fallacies of assumption (Conjecture)
• Have false (or at least unwarranted) assumptions,
  which fails to establish inference to the
  conclusion (must be true). Assume one premise to
  be true

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Fallacies of ambiguity

• Word choices makes a confusing premise

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Equivocation

• Words often have more than one meaning
• Different definition of word or phrase
• Use subjective or relative words or phrases
• Tall/Short
• Hot/Cold
• What are rights?
• Whats a good salary?
• Whats a good mate?
• Im to see the Doctor

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Amphiboly

• Grammatical error leads to confusion.
• Bad or unclear writing/speaking
• A man shot himself after making a fond farewell
  to his family with a shotgun
• Is it the man shot himself with a shot gun or
  that he gave his family a fond farewell with a
  shotgun
• Ad for an apartment 3 rooms, river view, private
  phone, bath, kitchen, utilities included
• Is it just a private phone or private phone, bath
  and kitchen?

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Accent

• Different emphasis on certain words changes
  meaning or context
• THESE (!) are your friends
• These are YOUR (!) friends
• You misinterpret the meaning because of and
  accent on a word or phrase
• Can be cultural or regional
• Automobile story

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Composition

• The whole is like the individual
• Buses use more gas then cars
• True one bus to one car BUT NOT ALL buses to ALL
  cars (more cars)
• Can be fixed by clarifying wording
• Most buses uses more gas than automobiles, but
  there are more automobiles. Thus, as a whole-
  automobiles use more gas

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Division

• The pieces are like the whole
• This hotel must have nice suites because the
  outside and lobby is so nice.
• The whole car is of quality means every part in
  the car is of quality
• ALL men are DOGS. Mr. V is a man, therefore Mr. V
  is a DOG!

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Name that Fallacy
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Fallacies of relevance

• Premises are unrelated to conclusion

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Emotion

• Rely on the feelings of the audience to influence
  ones argument
• Patriotic speeches (Hitler)
• Ads on TV (Shoes-- Athlete)
• Appeal to pity (Court Cases)
• I was late for work that is why I was speeding

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Red Herring- distraction

• Distract the other person from real argument or
  too ambiguous of a connection.
• Loose(n) focus.
• Gambling is good because taxes are too high
• We need to be in Iraq, only 800 Iraqi soldiers
  (T/F?)
• Duke (2006) Three students accused of rape, one
  professor defended the prosecutors indictment by
  saying that the real bad thing is that 18 of the
  population was below the poverty line.

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Straw Man

• Change opponents argument. Putting words in
  opponents mouth to make it easier to refute or
  beat
• When you talk about universal health care you are
  talking about Socialism.
• When you are talking about same sex marriage you
  are saying we need to destroy the family dynamics
  in the US.

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Against the personLatin ad hominem

• You dont attack argument you attack the person
  who is arguing with you
• Abusive Direct attack on the person
• If against affirmed action, then you are a racist
• If you are a liberal, then you are part of the
  Loony Left
• Circumstantial Attack a persons status/group.
  Also called Poisoning the well
• If you go to that school, then you are not smart
• If those are your friends then you are bad too

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Appeal to force

• To force someone to accept a claim with a
  physical or physiological confrontation
• Physical force
• Lawsuits to scare
• Symbols to influence
• Nazi
• American Flag
• Police shield

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From Ignorance

• Assume true because not proven false
• OR
• Assume false because not proven true
• You have to make your own argument
• You cant prove UFOs are false so they must be
  true
• You cant prove Im guilty so I must be Innocent.
  

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Name that Fallacy
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Fallacies of Assumptions

• Assume premise to be true without proof

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Begging the question

• The conclusion is just a rewording of one of the
  premises. Also called circular logic
• Freedom of speech is good because everyone is
  free to say what they want.
• Capital punishment is wrong because you are
  putting someone to death is wrong.
• God exists because the bible says so (which is
  the word of God)

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Inappropriate Authority

• Use testimony of expert (credibility) in an area
  that they are not an expert in.
• Politics
• The president thinks genetic engineer is
  wrong/right
• Is he/she a scientists?
• Ads
• Tiger Woods Drives this car
• Does he race or engineer cars?

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Loaded (Complex) Question

• Suppose the truth of another question in a
  premise to justify the conclusion
• How did you feel when you took all that money
  from the bank?
• Assumes you did take it and the question asks
  about your emotions
• You support the right to bear arms and the
  Republican Party.
• Assumes you support both causes

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False Dilemma

• Forces the argument into two choices when there
  are many. Limits your options.
• Very popular in Politics, sports and
  relationships
• Either you are with us or against us
• Either you like the team or hate the team
• Either you love me or you dont

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False Cause

• The casual relationship in a premise is not a
  true relationship.
• Less religion in school causes gangs
• Death penalty decreases crime
• Could be plenty of other factors that cause
  gangs and decreases crime. Could be one factor,
  but maybe not the most important one

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Name that Fallacy
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Strategies for avoiding fallacies

• Know yourself
• Knowing which fallacies you use
• Build your self-confidence and self-esteem
• Notice and address fallacies in others, make good
  argument yourself
• Cultivate good listening skills
• Avoid ambiguous and vague terms and faulty
  grammar
• Clearly define your key terms.
• Adopt a position of skepticism
• Dont just take peoples word for it. Also remain
  skeptical about your own position.