LOGICAL FALLACIES

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LOGICAL FALLACIES

• Informal Reasoning

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FALLACY

• A fallacy is a failure in reasoning that leads to
  an argument being invalid.
• They are like cracks in the foundation of a
  building if they are present, the building is
  going to fall down.

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WHY SHOULD WE LEARN FALLACIES?

• Detecting fallacies is a very important part of
  making yourself critically skilled.
• If you know what fallacies are, you can
• Avoid making them yourself when you present an
  argument.
• Spot them when others are using them.

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WHO USES FALLACIES?

• Everyone at times.
• Some are present innocently.
• Some are done deliberately.
• Advertising
• Politics
• Media
• Law

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10 LOGICAL FALLACIES

1. Hasty generalization
2. Post hoc ergo propter hoc
3. Ad hominem fallacy
4. Circular reasoning
5. Special pleading

1. Equivocation
2. Argument ad ignorantiam
3. False analogy
4. False dilemma
5. Loaded questions

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HASTY GENERALIZATION

• Generalizing from not enough evidence
• Stereotyping
• Example Hes Mexican so he must know how to
  garden.

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POST HOC ERGO PROPTER HOC

• An immediate jump to a conclusion without enough
  or very little evidence.
• Something is not the cause of something else just
  because they follow each other.
• Example People who drink one glass of wine a
  day have a lower chance of heart disease.

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AD HOMINEM FALLACY

• Rejecting what someone says solely on the basis
  of whom they are or what they believe.
• Attacking or critiquing the person instead of
  critiquing the argument or point made.
• Example President Wilson supported the League
  of Nations so it must be a good thing.

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CIRCULAR REASONING

• Vicious circle One negative action/idea or
  wrong way of thinking leads to another.
• Just assuming something is true when you are
  supposed to be proving it.
• I know that Sandra is innocent because Sandra
  would not lie to me.

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SPECIAL PLEADING

• Just because you are in a crisis, you believe
  that you deserve the second chance.
• Having Double Standards Do as I say, not as I
  do.
• Example The city has asked residents to
  conserve water, everyone is expected to limit
  things such as showers but you make an exception
  for yourself after all you hair is long and
  thick.

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EQUIVOCATION

• A term used in two or more senses with a single
  argument.
• Comparing two like things that are not really
  alike or language is ambiguous or unclear.
• Example A hamburger is better than nothing
  nothing is better than good health therefore, a
  hamburger is good health.

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ARGUMENT AD IGNORANTIAM

• To claim that something is true on the grounds
  that there is no evidence to dispute it.
• Example I believe zombies exist because no one
  can prove they dont.
• Example I believe God exists because no one can
  prove that he doesnt.

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FALSE ANALOGY

• Just because two things are similar in some
  situations does not mean they are in all
  situations.
• Example Just as in time the gentle rain can
  wear down the tallest mountains, so, in human
  life, all problems can be solved by patience and
  quiet persistence.

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FALSE DILEMMA

• Assuming only two black and white dilemmas exist
  or divide things into two types.
• When you leave little option or only two options-
  when in reality, things are rarely so simple.
• Example Do people who want to see an increase
  in military spending really want to see our
  schools close? (This makes it sound like tax
  money either goes entirely to military or
  entirely to education.)

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LOADED QUESTION

• To put an assumption in a question.
• A question with a false, disputed, or
  question-begging presupposition.
• Example Do you always cheat on tests?
• It is assuming that you have cheated on tests at
  some point in time.