Here is a list of everyday fallacies
compiled by Dr. Kenneth B. Hunt
We've all probably made
easily avoidable errors of logic. Therefore, everyone will want to read a list
like this in order to avoid doing so in the future.
Ambiguity Fallacies
AMPHIBOLY:
A fallacy of syntactical ambiguity deliberately misusing implications. Example:
"Three out of four doctors recommend this type of pain relief!" The
implied assertion here is that three out of four means seventy-five percent of
all doctors and that this type of pain relief means this particular pain
reliever.
EQUIVOCATION:
This fallacy is a product of semantic ambiguity. The arguer uses the ambiguous
nature of a word or phrase to shift the meaning in such a way as to make the
reason offered appear more convincing. Example: An ad from a
sugar company says "Sugar is an essential component of the body, a
key material in all sorts of metabolic processes, so buy some P&R sugar
today." The word "sugar" is being used with two definitions that
the ad does not acknowledge.
Appeals to Motive in Place of Support Fallacies
APPEAL TO EMOTION:
In this fallacy, the arguer uses emotional appeals rather than logical reasons
to persuade the listener. The fallacy can appeal to various emotions including
pride, pity, fear, hate, vanity, or sympathy. The appeal to sympathy is
actually a formal fallacy labeled Ad Misericordiam. Generally, the issue is
oversimplified to the advantage of the arguer. Example: In 1972,
there was a widely printed advertisement printed by the Foulke Fur Co., which
was in reaction to the frequent protests against the killing of Alaskan seals
for the making of fancy furs. According to the advertisement, clubbing the
seals was one of the great conservation stories of our history, a mere exercise
in wildlife management, because "biologists believe a healthier colony is
a controlled colony."
COMMON BELIEF:
This fallacy is committed when we assert a statement to be true on the evidence
that many other people allegedly believe it. Being widely believed is not proof
or evidence of the truth. Example: Of course Nixon was guilty in
Watergate. Everybody knows that.
PAST BELIEF:
A form of the COMMON BELIEF fallacy. The same error in reasoning is committed
except the claim is for belief or support in the past. Example: Everyone
knows that the Earth is flat, so why do you persist in your outlandish
claims?
SLANTING: A form of misrepresentation in which a true
statement is made, but made in such a way as to suggest that something is not
true or to give a false description through the manipulation of connotation. Example:
I can't believe how much money is being poured into the space program
(suggesting that 'poured' means heedless and unnecessary spending)
Causal
Fallacies
GENUINE BUT INSIGNIFICANT
CAUSE: The object or event identified as the cause of an
effect is a genuine cause, but insignificant when compared to the other causes
of that event. Example: Smoking is causing air pollution in our
cities. (True, but the effect of smoking is insignificant compared to the
effect
of auto exhaust.) or By leaving your air conditioner on overnight you are
contributing to global warming.
POST HOC ERGO PROPTER HOC:
A form of a hasty generalization in which it is inferred that because one event
followed another it is necessarily caused by that event. Example:
Mary joined our class and the next week we all did poorly on the quiz. It must
be her fault.
Changing the Subject Fallacies
ATTACKING THE PERSON or
Ad Hominum. Attacking the arguer rather than his/her
argument. Saying something negative about someone is not automatically ad
hominum. If a person (politician for example) is the issue, then it is
not a fallacy. Example: John's objections to capital punishment
carry no weight since he is a convicted felon.
APPEAL TO AUTHORITY or Ad
verecuniam. This fallacy tries to convince the listener by
appealing to an expert. Often times it is an authority in one field who is
speaking out of his field. Example: Sports stars selling cars or
hamburgers. Or, the actor on a TV commercial that says, "I'm not a doctor,
but I play one on TV."
Definition Fallacies
BEGGING THE QUESTION:
An argument in which the conclusion is implied or already assumed in the premises.
Also said to be a circular argument. Example: Of course the Bible
is the word of God. Why? Because God says so in the Bible.
Distraction Fallacies
APPEAL TO IGNORANCE or Ad
ignorantium. Arguing on the basis of what is known and can be
proven. If you can't prove that something is true then it must be false (and
vice versa). Example: You can't prove there isn't a Loch Ness
Monster, so there must be one.
FALSE DILEMMA
(often called the either/or fallacy because the argument nearly always
includes the words "either... or..."). This fallacy assumes that we
must choose between two opposite extremes instead of allowing for other
possibilities, especially for the possibility of choosing an alternative
between the extremes. Example: Women need to be either brilliant
or beautiful to survive in this world.
SLIPPERY SLOPE or
: A line of reasoning in which there is no gray area or middle ground. It
states that x, y, z are implicit in step a. The primary characteristic is that
it fails to distinguish between (or among) degrees of difference. It argues for
(or against) the first step because if you take the first step, you will inevitably
follow through to the last. Example: We can't allow students any
voice in decision-making on campus; if we do, it won't be long before they are
in total control.
Explanation Fallacies
QUESTIONABLE CAUSE.
The fallacy of questionable cause is committed when, on insufficient evidence,
we identify a cause for an occurrence that has taken place or a fact that is
true. Example: I can't find the checkbook; I am sure that my
husband hid it so I couldn't go shopping today.
UNTESTABILITY:
The theory advanced to explain why some phenomena occurs cannot
be tested. We test a theory by means of its predictions. For example, a theory
may predict that light bends under certain conditions, or that a liquid will
change color if sprayed with acid, or that a psychotic person will respond
badly to particular stimuli. If the predicted event fails to occur, then this
is evidence against the theory.
A theory cannot be tested
when it makes no predictions. It is also untestable when it predicts events
which would occur whether or not the theory were true. Example: Aircraft
in the mid-Atlantic disappear because of the effect of the Bermuda Triangle, a
force so subtle it cannot be measured on any instrument. (The force of the
Bermuda Triangle has no effect other than the occasional downing of aircraft.
The only possible prediction is that more aircraft will be lost. But this is
likely to happen whether or not the theory is true.)
Inductive Fallacies
ARGUMENT FROM ANALOGY or
FALSE ANALOGY: An unsound form of inductive argument in which an
argument is based completely or relies heavily on analogy to prove its point. Example:
This must be a great car, for, like the finest watches in the world, it was
made in Switzerland.
FAR-FETCHED HYPOTHESIS:
A fallacy of inductive reasoning that is committed when we accept a particular
hypothesis when a more acceptable hypothesis, or one more strongly based in
fact, is available. Example: The African-American church was set
afire after the civil rights meeting last night; therefore, it must have been
done by the leader and the minister to cast suspicion on the local
segregationists.
HASTY GENERALIZATION: A
generalization accepted on the support of a sample that is too small or biased
to warrant it. Example: All men are rats! Just look at the louse
that I married.
Missing the Point Fallacies
CONTRARY TO FACT
HYPOTHESIS: This fallacy is committed when we state with an
unreasonable degree of certainty the results of an event that might have
occurred but did not. Example: If President Bush had not gone
into the Persian Gulf with military force when he did, Saddam Hussein would
control the world's oil from Saudi Arabia today.
RED HERRING:
This fallacy introduces an irrelevant issue into a discussion as a diversionary
tactic. It takes people off the issue at hand; it is beside the point.
Example: Many people say that engineers need more practice in writing,
but I would like to remind them how difficult it is to master all the math and
drawing skills that an engineer requires.
STRAW MAN:
This fallacy occurs when we misrepresent an opponent's position to make it
easier to attack, usually by distorting his or her views to ridiculous
extremes. This can also take the form of attacking only the weak premises in an
opposing argument while ignoring the strong ones. Example: Those
who favor gun-control legislation just want to take all guns away from
responsible citizens and put them into the hands of the criminals.
TWO WRONGS MAKE A RIGHT:
This fallacy is committed when we try to justify an apparently wrong action by
charges of a similar wrong. The underlying assumption is that if they do it,
then we can do it too and are somehow justified. Example: Supporters
of apartheid are often guilty of this error in reasoning. They point to U.S.
practices of slavery to justify their system.
Non Sequitur Fallacies
NON SEQUITUR:
In this fallacy the premises have no direct relationship to the conclusion.
This fallacy appears in political speeches and advertising with great
frequency. Example: A waterfall in the background and a beautiful
girl in the foreground have nothing to do with an automobile's performance.
Fallacy: Loaded Questions:
Your critical thinking instructor: Aren't you ashamed about how little effort you've made in this class?
Questions like the one in the first example are usually
called loaded questions, because, like loaded dice, they seem to produce
a predictable outcome: as long as the response to a complex question or claim
is simple, usually just "yes" or "no," then the person
responding seems to be assenting to something he or she normally would not.
A Word about Argument
In order to understand what a fallacy is, one must
understand what an argument is. Very briefly, an argument consists of one or
more premises and one conclusion. A premise is a statement (a sentence that is
either true or false) that is offered in support of the claim being made, which
is the conclusion (which is also a sentence that is either true or false).
There
are two main types of arguments: deductive and inductive. A deductive argument
is an argument such that the premises provide (or appear to provide) complete
support for the conclusion. An inductive argument is an argument such that the
premises provide (or appear to provide) some degree of support (but less than
complete support) for the conclusion. If the premises actually provide the
required degree of support for the conclusion, then the argument is a good one.
A good deductive argument is known as a valid argument and is such that if all
its premises are true, then its conclusion must be true. If all the argument is
valid and actually has all true premises, then it is known as a sound argument.
If it is invalid or has one or more false premises, it will be unsound. A good
inductive argument is known as a strong (or "cogent") inductive
argument. It is such that if the premises are true, the conclusion is likely to
be true.
A
fallacy is, very generally, an error in reasoning. This differs from a factual
error, which is simply being wrong about the facts. To be more specific, a
fallacy is an "argument" in which the premises given for the
conclusion do not provide the needed degree of support. A deductive fallacy is
a deductive argument that is invalid (it is such that it could have all true
premises and still have a false conclusion). An inductive fallacy is less
formal than a deductive fallacy. They are simply "arguments" which
appear to be inductive arguments, but the premises do not provided enough
support for the conclusion. In such cases, even if the premises were true, the
conclusion would not be more likely to be true.
Sources:
http://www.sjsu.edu/depts/itl/graphics/main.html
