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