PART 3:
THE FALLACIES
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I. INSUFFICIENT
EVIDENCE
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INSUFFICIENT EVIDENCE
• FAULTY INDUCTION: Inductive Fallacies
– quantity: not enough evidence upon which to draw a
reasonable conclusion
– quality: unreliable data or sources
• bad Ethos
• implications, assumptions, inferences (not facts)
• FAULTY DEDUCTION: Deductive Fallacies
– flawed Major Premise (generalization)
– flawed Minor Premise (specific, observation)
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INSUFFICIENT EVIDENCE
1) OVERGENERALIZATIONS:
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hasty, false, sweeping generalizations
dicto simpliciter (spoken simply)
implies ALL
uses INDEFINITE PRONOUNS:
– all, everyone, everybody
– no one, nothing
– everything, anything, always
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INSUFFICIENT EVIDENCE
1) OVERGENERALIZATIONS:
• EASILY DISPROVED: too many exceptions
and too many complications (life = too complex)
• QUALIFY WITH:
– many, some, few
– usually, often, in my experience
• DANGER with qualifying: too many maybe’s in your
writing may make you look indecisive
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INSUFFICIENT EVIDENCE
*EXAMPLES of OVERGENERALIZATIONS:
• *stereotypes, prejudices, superstitions:
– racism, ageism, sexism
– “Teenagers today are fat and lazy.”
– “Men don’t cry.”
• Hasty generalization: “Jim Bakker was an insincere Christian.
Therefore, all Christians are insincere.”
• Sweeping generalization: “Christians generally dislike atheists.
You are a Christian, so you must dislike atheists.” (senior citizens,
Asians, guys, Americans = materialistic, war-mongers)
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INSUFFICIENT EVIDENCE
2) STACKING the DECK (a.k.a. “card stacking”):
• poker metaphor:
– dealing yourself a good hand;
– stacking the card deck in your favor
• selecting only the data that supports your position
• ignoring contradictory data
– (only 1 side of the issue)
– (*needs other side/s of the issue)
• news bias, politicians, tobacco/oil industries
• fraudulent, misleading
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INSUFFICIENT EVIDENCE
*EXAMPLES of CARD STACKING:
• “Ninety-five percent of the people I interviewed agreed
with the Democratic Opposition.”
• BUT I only interviewed people at the Democratic
National Convention!
• “According to a Left-Wing Nut magazine poll, the Vice
President has a low approval rating.”
• BUT only those people who read—i.e., agree with the
ideology of—this publication were polled.
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INSUFFICIENT EVIDENCE
3) AD IGNORANTIUM:
• since cannot disprove (or prove), then must be true
• assumes a lack of information (“ignorance”) is a source
of information (*needs more info)
• yet, an absence of evidence is not evidence
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INSUFFICIENT EVIDENCE
• CARD STACKING vs. AD IGNORANTIUM:
– Don’t be fooled by the “ignoring” part –
• CS: purposefully ignores existing evidence
 data that will disprove or weaken that side
 the data does exist but is ignored
• AI: uses ignorance as evidence
 uses the lack of existing evidence as evidence
 the lack of evidence = the proof
 the data does not exist
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INSUFFICIENT EVIDENCE
*EXAMPLES of AD IGNORANTIUM:
• “Since the library has no books on Eva Braun’s intimate
relations with Adolf Hitler, then she must not have had
any.”
• “Of course the Bible is true. Nobody can prove
otherwise.”
• “Of course telepathy and other psychic phenomena do
not exist. Nobody has shown any proof that they are
real.” (aliens, ghosts)
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INSUFFICIENT EVIDENCE
4) POST HOC ERGO PROPTER HOC:
• “after this, therefore b/c of this”
• assumes a causal relationship;
– no other explanations
– faulty Cause-Effect relationship
• assumes a later event was caused by an earlier one
– simply because of chronology
– *needs more info, more research
• B follows A; therefore, A causes B
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INSUFFICIENT EVIDENCE
• DISPROVE with: (more information)
– prove A and B are merely coincidences
– show how A is merely 1 cause of many
– show how A is not even a significant cause of the many
• *more than 1 cause of an effect, more than 1 effect of a cause
• indirect and direct causes
• complexity of life, of situations
– OCCAM’S RAZOR:
• simpler, more credible answer or explanation is best
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INSUFFICIENT EVIDENCE
• PHEPH: Superstitions
• <boston.com >
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INSUFFICIENT EVIDENCE
*EXAMPLES of P.H.E.P.H.:
• superstitions, astrology
• Consider additional causes for the following:
• “Because you left the milk out last night, it was spoiled
this morning.”
• “The Soviet Union collapsed after instituting state
atheism. Therefore, we must avoid atheism for the same
reasons.”
• “A rooster crows every morning, and shortly after, the
sun rises. Therefore, the rooster causes the sun to rise.”
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INSUFFICIENT EVIDENCE
*EXAMPLE of P.H.E.P.H.:
• “After the school principal suspends daily prayers in the
classroom, acts of vandalism increase, and some parents
are convinced that the failure to conduct prayer is
responsible for the rise in vandalism.”
• But…decline in disciplinary actions, a relaxation of
academic standards, a change in school administration,
changes in family structure in the school community.
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INSUFFICIENT EVIDENCE
Post hoc ergo propter hoc:
• after this (subsequency), therefore because of this
Cum hoc ergo propter hoc:
• with this (synchronicity), therefore because of this
– mistakes a correlation for causation
– overlooks coincidence, others causes
– because of simultaneous occurrence
– “Clinton had great economic policies because the
economy was great during his two terms.”
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INSUFFICIENT EVIDENCE
5) AD HOC:
• “for this (specific purpose)” – “impromptu, provisional”
• an after-the-fact explanation
• does not apply to other situations (for this special case alone)
• “God cured me of my cancer.” “But most patients with brain
cancer die. Why did She save you? Are you special? Does She
love you more than the rest of us?” “She moves in mysterious
ways.”
– because God treats all people equally, no special treatment
– refuted by more evidence (radiation, medication, remission)
– see also God & war, God & sports
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INSUFFICIENT EVIDENCE
6) The Natural Law Fallacy -- Appeal to NATURE:
• draws a false analogy between the human and natural
worlds
• assumes that humans are part of the natural world
(animals) and should thus mimic “animalistic” behavior
• assumes that whatever is “natural” or consistent with
“nature” is good AND that whatever is “unnatural” is
bad
– supplements, herbal remedies
– “law of the jungle” arguments for genocide, capitalism
– “Homosexuality is natural because monkeys have been
observed engaging in homosexual behavior.” (or the opposite)
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INSUFFICIENT EVIDENCE
6) The Natural Law Fallacy -- Appeal to NATURE:
• BUT
– “natural” and “nature” = poorly defined
– just because animals do it (or don’t) does not mean
humans should (or shouldn’t) do so automatically,
necessarily, unquestionably
– naïve environmentalism
– poison ivy, Ebola, climate, eat their young, eat bugs
– bathrooms, plumbing, fire, literature, clothes, utensils
END
PART 3A