Fallacies in Reasoning
Fallacy - An argument that is flawed by irrelevant or inadequate evidence,
flawed reasoning, or improper expression. It is an incorrect argument. EX:
That the world is flat was at one time a popular fallacy.
I.
Fallacies of Faulty Reasoning – occur when the inferences drawn
fail to meet one or more of the relevant tests of reasoning.
Types
A. Faulty Analogy – assumes that because two things, events, or
situations are alike in some known respects, they are alike in other
unknown respects; compares two things that are not alike in significant
respects or have critical points of difference.
- EX. What’s the big deal about the early pioneers killing a
few Indians in order to settle the West? After all, you can’t
make an omelet without breaking a few eggs.
- EX. We should not teach socialism in the university
anymore than we should teach arson.
B. Hasty Generalization – a single example (or too small a sample)
is used as the basis for a broader generalization; generally extrapolates
characteristics from some to all members of a class or may also
attribute the characteristics of a class to its individual members.
* Two tests for a generalization – ask whether enough
members of a class have been observed, and ask whether those
members are truly typical.
- EX. All of those famous singers are really rude. I asked
Jennifer Lopez for her autograph, and she told me to get lost.
-EX. Speech Communication is a really boring major. I took
Intro. to Public Speaking from Dr. Smith, and I was never so bored in
all my life.
C. Faulty Cause – mistakes association/correlation for causation; by
assuming that because one thing follows another, it was caused by the other.
Common reasoning fallacies dealing with causal reasoning:
1. Post Hoc – makes sequential succession for causal
sequence; one assumes that because two events are
associated in time, one event must have caused the other.
Although one condition followed the other, it does not prove
that there is a causal relationship that connects the
antecedent with the consequence.
a. EX. A black cat crossed Sue’s path yesterday, and,
sure enough, she was involved in an automobile
accident later that same afternoon.
2. Single Cause – occur when an advocate attributes only one
cause to a complex problem. For any complex social,
political, or economical problem, there is more than one
cause; it should not be oversimplified.
a. EX. Poor communication is the reason for the high
American divorce rate.
II.
Fallacies of Grounding – stem from a lack of evidence or poor
use of evidence.
Types
1. Slippery Slope (Snowball Argument) – it is a fallacy
of evidence use; it assumes without evidence, that a
given event is the first in a series of steps that will lead
inevitably to some outcome. It suggests that if one step
or action is taken, it will invariably lead to an
undesirable situation.
a. EX. If we let people in from other
countries, our whole country will be overrun
with terrorists before 2010.
b. EX. If the Supreme Court allows abortion,
next thing you know they’ll allow
euthanasia, and it won’t be long before
society disposes of all those persons whom
it deems unwanted or undesirable.
c. EX. Allowing abortion in the first week of
pregnancy would lead to allowing it in the
ninth month.
2. Circular Argument (Begging the Question) –What's
the difference between a valid deductive argument
and a fallacy? In the case of the fallacy of circular
reasoning, the difference is not be as obvious as you
might expect. In the fallacy of circular reasoning,
which is often called begging the question, you
assume to be true what you are supposed to be
proving. But that's also true for all valid deductions,
where the conclusion (what you are trying to prove) is
derived from the premises or assumptions. This
difference is that, in circular reasoning, the conclusion
is contained in a single premise or assumption,
while in a deductive argument the conclusion is
derived from both premises. Consider the following
exchanges:
Deductive Reasoning (Valid)
Sports Fan #1: What makes you say Australian Rules Football is the
most exciting sport in the world?
Sports Fan #2: Because it is the fastest and highest scoring form of
football, and whatever is the fastest and highest scoring form of
football must be the most exciting sport in the world.
Circular Reasoning (Fallacious)
Sports Fan #1: What makes you say Australian Rules Football is the
most exciting sport in the world?
Sports Fan #2: Because it is.
In both examples, the conclusion has been assumed in the
premises. But the first argument follows a valid pattern:
If P (fastest and highest scoring), then Q (most exciting).
Aussie Rules Football is P (fastest and highest scoring),
therefore Aussie Rules Football is Q (most exciting). But
in the second example, the one for circular reasoning, the
conclusion has been assumed entirely (or almost entirely)
in a single premise. As a result, the conclusion of a
circular argument can be seen as just a restatement of its
only premise. It's like saying, "A is B, therefore A is B."
Often, however, circular reasoning is more subtle than
this: it depends on an assumption not stated but assumed.
Consider the famous argument of the French philosopher,
René Descartes: "I think, therefore I am." Descartes has
begged the question here, because when he said "I think,"
he'd already implied "I am" (or how else could he
think?). Yet his fallacy continues to persuade people,
over three hundred years later
3. Appeal to Authority – attempts to justify an argument
by citing a well-known (but not necessarily qualified)
figure, who supports the conclusion being offered.
a. EX. If it’s good enough for Michael Jordan, it’s
good enough for me.
b. EX. Laws against marijuana are plain silly.
Why, Thomas Jefferson is known to have raised
hemp on his own plantation.
2. Appeal to Ignorance – Attempts to use an opponent’s
inability to disprove a conclusion as proof of the
validity of the conclusion, i.e. “You can’t prove I’m
wrong, so I must be right.”
a. EX. The new form of experimental
chemotherapy must be working—not a
single patient has returned to complain.
b. EX. We can safely conclude that there is
intelligent life elsewhere in the galaxy
because thus far no one had been able to
prove that there is not.
3. Non Sequitur (does not follow) – contains a claim that
is irrelevant to or unsupported by the evidence or
premises supporting it. The evidence fails to support
the claim. Ask yourself, “Does this evidence support
this claim?” A statement (as a response) that does not
follow logically from or is not clearly related to
anything previously said.
a. EX. This week has been really rough.
Well, it’s Friday.
b. "Tens of thousands of Americans have seen
lights in the night sky which they could not
identify. The existence of life on other
planets is fast becoming certainty!"
Comics: Non Sequitur
III.
Fallacies of Misdirection – focuses the audience’s attention away
form relevant issues by often appealing to the audience and not to
the arguments.
Types
1. Damning the Source (Ad Hominem – “to the man”)
– attempts to refute an argument by condemning the
source of the argument, rather than the substance of the
argument. Launches an irrelevant attack on the person
or source originating an argument instead of responding
to substantial issues raised in the argument.
1. EX: Marge Schott has no right to criticize umpire
procedures because she is a racist.
2. EX: One cannot place credence in the arguments
of conscientious objectors for they are only
cowards attempting to beat the draft.
2. Look Who’s Talking – points to a similar wrong or
error committed by another
1. EX: Who do the Catholic priests think they are
telling me to live a moral life. They’re the ones
abusing children.
2. EX: If joining the Army is such a good idea, then
why aren’t you in it?
3. Appeal to Tradition – things should continue to be
done in the same way they have been done in the past
1. EX: We should not spend any time or money
developing non-gasoline powered cars. After all,
we’ve been successfully using gasoline-powered
cars for almost 100 years.
4. Appeal to the Crowd (Ad Populum) – refers to
popular opinion or majority sentiment in order to
provide support for a claim; often the “common man”
or “common sense” provides the basis for the claim.
The substance of an argument is avoided and the
advocate appeals instead to popular opinion as a
justification for the claim. The argument’s claim is
predicted on popular beliefs and opinions rather than on
reason and evidence.
1. EX: The Sound of Music is the greatest movie
ever made; it has been seen by more people than
any other motion picture.
2. EX: 85% of people polled believe fluoride in water
causes cancer. Therefore, we should ban it from
our water supplies.
5. Straw Man – stating an opponent’s argument in an
extreme or exaggerated form, or attacking a weaker,
irrelevant portion of an opponent’s argument. People
often attribute foolish arguments to their opponents and
ignore what they really did say.
1. EX: What woman in her right mind could truly
desire total equality with men? No woman wants
the right to be shot at in times of war, the right to
have to pay alimony, or the right to have to use the
same restrooms as men.
2. Senator Jones says that we should not fund the
attack submarine program. I disagree entirely. I
can't understand why he wants to leave us
defenseless like that.
a. People often exaggerate an opponent’s
argument so that he may be compared to
Hitler
IV.
Fallacies of Language Use – occur when words and grammar are
used by an arguer to mislead or confuse the recipients.
1. Equivocation (Ambiguity) – allows a key word or
term in an argument to shift its meaning during the
course of the argument. The result is that the
conclusion of the argument is not concerned with the
same thing as the premise. The person exploits the fact
that a word has more than one meaning so as to lead to
a false conclusion.
1. EX: Only man is rational. No woman is a man.
Therefore, no woman is rational. (man)
2. EX: Turing thinks machines think.
Turing lies with men.
Therefore, machines don't think. (lies)
2. Either/Or (All or Nothing) – Something is either a
member of one category or another, but not both or
some third category; assumes that two categories are
mutually exclusive and exhaustive
1. EX: America: love it or leave it.
2. EX: Either you favor a strong national defense, or
you favor allowing North Korea to dictate our
foreign policy.
3. False Dilemma – similar to either/or as it implies that
one of two outcomes is inevitable, but both have
negative consequences
1. EX: Either you buy a large car and watch it guzzle
away your paycheck, or you buy a small car and
take a greater risk of being injured or killed in the
event of an accident.