fallacies common and recurrent errors in reasoning important strategy to identify them: treat...

FALLACIES

COMMON AND RECURRENT ERRORS IN REASONING

IMPORTANT STRATEGY TO IDENTIFY THEM: TREAT PASSAGE AS AN ARGUMENT WITH PREMISE AND CONCLUSION AND DETERMINE WHAT SORT OF STRUCTURE IT FOLLOWS.

THE TWO CLASSES

Irrelevant Premises

Unacceptable Premises

IRRELEVANT PREMISES

GENETIC FALLACY Origin of claim used as reason why

claim is true or false Source of claim is irrelevant to its

truth “Russell’s idea about job creation was

produced when he was in a drunken state, so it must be flawed.”

COMPOSITION

COMPOSITION: P IS TRUE OF ONE PART OF

SOMETHING P IS TRUE OF THE WHOLE THING

Watch for context of statistics!

Flip side of composition P IS TRUE OF THE WHOLE THING

P IS TRUE OF ONE SPECIFIC PART OF THING

DIVISION

APPEAL TO THE PERSON

Ad hominem (to the person) Structure: X SAY P + X HAS SOME NEGATIVE

TRAIT

P IS NOT TRUE

FORMS: CRUDE FORM: NAME CALLING AND

INSULTS

OTHER FORMS AND SPECIES OF AD HOMINEMS TU QUOQUE “YOU’RE ANOTHER” OR

THE POT CALLING THE KETTLE BLACK(hypocrisy) POISONING THE WELL: X HAS A VESTED INTEREST IN THE

TRUTH OF P P IS UNTRUE

EQUIVOCATION

EQUIVOCATION (MANY VOICES) SWITCHING MEANING OF WORD IN

MIDSENTENCE OR IN ARGUMENT, EITHER PREMISES OR CONCLUSIONS.

PLAY ON WORD MEANING P. 174 EXAMPLE

APPEAL TO POPULARITY

Also called “appeal to majority” Structure: Everyone (or almost everyone)

believes X,

X is true

“The vast majority of Canadians believe that the monarchy is a good thing.”

Therefore …

APPEAL TO TRADITION

Truth of claim is dependent on being part of tradition

Also similar to “subjectivism” Subjectivism: “I belief X, therefore

X is true.” “I was brought up to believe that X

is true, therefore X is true” “Acupuncture has been used for a

thousand years in China. It must work.”

APPEAL TO IGNORANCE

Use of lack of evidence for support of claim

TWO STRUCTURES: 1. P HAS NOT BEEN PROVED FALSE

P IS TRUE 2. P HAS NOT BEEN PROVED TRUE P IS FALSE

APPEAL TO IGNORANCE, cont.

Scientific research and justification when evidence is lacking

Burden of ProofWhen burden of proof is placed on

wrong side!Burden always falls on claimant

A form of baiting

APPEAL TO EMOTION

STRUCTURE: AN EMOTIONAL RESPONSE OCCURS

DUE TO P

P IS TRUE OR P IS FALSE

RED HERRING

USE OF HERRINGS TO DIVERT THE SMELL OF A HOUND DOG AWAY FROM THE CRIMINAL’S PATH.

FORM 1. PROPOSITION P IS TRUE PROPOSITION Q IS TRUE

RED HERRING, continued

FORM 2. THERE IS GOOD REASON TO

BELIEVE Q IS TRUE

P IS TRUE

STRAW MAN

MISREPRESENTATION, DISTORTION, OVERSIMPLIFYING AN ARGUMENT OR CLAIM OR THEORY TO WEAKEN IT AND FIND IT FAULTY.

Structure: Reinterpret claim X so it is weak or

absurd

Claim X is faulty of untrue

FALLACIES WITH UNACCEPTABLE PREMISES

Begging the Question or Circular Argument

Structure: P (a claim is made)

P (same claim is made) SAME CLAIM IS PREMISE AND

CONCLUSION!

BEGGING THE QUESTION, cont.

Bible says that God exists

Therefore, God exists

Why is Bible to be accepted? (asking for evidence for premise)

Because God exists. (Use of conclusion as premise for first premise)

FALSE DILEMMA (ALTERNATIVE) Presents only 2 alternatives, rejects one

so as to assert the other.

Disregard for other possibilities

“either those lights you saw in the night sky were alien spacecraft or you were hallucinating.”

“You were not hallucinating, therefore….”

FALSE DILEMMA cont.

Sometimes applies to stand-alone phrases

e.g. “Microsoft: Bad cop or evil genius.”

“Jesus: lunatic or the son of God.”

Slippery Slope

Taking some step will lead down a slope towards some undesirable consequence

False consequence; appeal to fear Structure: Doing action X will lead to Y

Therefore, this will lead to Z, etc Domino effect e.g. Latimer case: Hunting season on the

disabled.

Hasty Generalization

Drawing a conclusion about a group or about all events from the experience of one or an individual. (Stereotypes) (inadequate sample)

Structure: One event or person y has X

Therefore all events or all persons of y have X

Faulty Analogy

Context: argument by analogy Fault: comparing different things or

essentially different things as if they were sufficiently similar

E.g. Watch and Intelligent design