THE NONSENSE
TRAPS: A GUIDE TO THE LOGICAL FALLACIES - Part 3
Welcome to
the Nonsense Traps
by Jonathan Dolhenty, Ph.D.
III.
Fallacies of Presumption
The type of logical fallacies to be discussed
here are sometimes called fallacies of presumption.
These are unsound arguments involving unfounded or
unproven assumptions contained within the premises.
They may appear to be sound arguments because they
appear similar to perfectly valid arguments. But,
although the conclusion of such arguments may seem
to follow logically from the premises, the fact is
that either significant facts are overlooked, or
significant facts are evaded, or significant facts
are distorted.
Begging the
Question
This form of logical fallacy is also known as
Petitio Principii. It's probably as old as human
history. It's an easy fallacy to commit and, for
this reason alone, should be watched for carefully.
What is involved here is simply explained. In an
argument containing this fallacy, one assumes as a
premise for his argument the very conclusion he
intends to prove.
Sometimes this type of fallacy is referred to as
the circular argument because that is exactly what
it is; it is an argument going around in a circle.
The conclusion is merely a restatement of something
explicitly stated in the premises.
- Example: Religious Leader -- "God
exists." Skeptic -- "How do you know?" Religious
Leader -- "The Bible says so." Skeptic -- "How
do you know what the Bible says is so?"
Religious Leader -- "It's the word of God!"
(This type of argument is atrocious. Any
religious leader who presents such an argument
should be severely criticized. The conclusion
"It's the word of God," is already contained in
the initial premise "God exists." It is a
glaring presumption. There may be many valid
arguments for the existence of God. This is not
one of them.)
- Example: Atheist -- "Miracles are
impossible." Religious Student -- "Why do you
say that?" Atheist -- "Because they cannot
happen." (This one is rather obvious. The
conclusion is clearly a restatement of the
initial premise. Whether or not miracles are
possible must rest on some other argument than
this one.)
- Example: Student Jones -- "I know
that Mr. Brown is an atheist." Student Smith --
"Why do you say that?" Student Jones -- "He's a
philosopher isn't he?" (This argument has an
implied judgment hiding in the initial premise.
The hidden judgment is that "All philosophers
are atheists." This, of course, is not
true.)
This latter example is seen more often than one
might suppose. It has been used particularly in the
United States during times of national stress. It
involves a form of the "guilt by association"
charge. For instance:
- Person A -- "I know that Tom Doe is a
Communist."
- Person B -- "And how do you know that?"
- Person A -- "Because he has read Karl Marx."
or "Because he is a supporter of civil rights."
or "Because he checked books out of the library
by a Socialist author." (There are also many
other possibilities. Person A is assuming that
only a Communist would read Karl Marx or support
civil rights or check out books by a Socialist
author. This assumption is totally unwarranted.
Mr. Doe may be a Communist but this rests on
other factors.)
Argument from
Ignorance
The fancy name for this fallacy is argumentum ad
ignorantiam. The fact that a proposition has not
been conclusively proven to be true or false,
especially when little or no real attempt has been
made to verify it, often establishes nothing but
one's inability to prove or disprove it. To treat
this inability as establishing the truth or falsity
of the proposition is to use a fallacious type of
argument.
The basic form of this type of fallacious
argument goes like this:
- There is no evidence or proof that it is the
case that X; therefore, it is not the case that
X.
A word of caution here. When confronted with an
argument that appears to have this form, we should
make sure that it cannot be reasonably interpreted
as a good inductive argument before we label it as
fallacious.
- Example: "Cancer is not caused by a
virus, since no conclusive evidence of the
existence of such a virus has been provided."
(Cancer may not, in fact, be caused by a virus.
But, just because such a virus has not yet been
found, does not permit us to draw the conclusion
that cancer is not caused by a virus. At this
time, we can only say that the question is still
pending. Of course, by the time this book is
published, medical scientists may have solved
the question.)
- Example: "There must be ghosts
because no one has ever been able to prove that
there aren't any." (The fallacy here should be
obvious. The proposition that "There must be
ghosts" does not follow from the premise that
"No one has ever been able to prove there aren't
any." This is arguing that a proposition is true
because it has not been proved false. Those who
promote claims about psychic phenomena, mental
telepathy, and other such "occult" events are
especially prone to this fallacy. If psychic
events do actually occur or can occur, the
evidence for them must be as clear and
convincing as required by any other scientific
(read inductive) claim. On the other hand, those
students of empirical science who claim that
psychic events do not or cannot occur because
they have not be proven are under the same
restraint. Their arguments are also fallacious.
Note: let's all wait until the evidence is
in.)
- Example: Amateur Theologian -- "God
exists because there is no evidence that he does
not." (This argument is a classic example of the
fallacy from ignorance. The argument for God's
existence must rest on positive evidence,
acquired either through deductive or inductive
methods. And remember: The one who asserts the
truth of a proposition is the one who must
rationally justify and validate it. It is not up
to the opponent to prove the case. This is
called the "Burden of Proof," and the burden
always rests with the one who asserts something,
as it is with the prosecutor in a court of law.
It is the prosecution who must prove, not the
defense.)
Speaking of prosecutors and courts of law, there
is an important point that should be made here
about this fallacy. While this fallacy applies in
most situations, there is one special context where
an exception is made and an argument of the type
described above is considered not fallacious. This
special context is in a court of law.
The guiding principle in American courts of law
is that a defendant is presumed innocent until
proven guilty. It can be legitimately argued by the
defense attorney that, if the prosecution has not
proved guilt, it requires a verdict of not guilty.
This claim is based upon a special legal principle
and does not affect the efficacy of the fallacy
from ignorance in other situations.
False
Cause
The fallacy of false cause involves the
inferring of a causal link between two events when
no such causal connection has been established. One
form of such a fallacy is called non causa pro
causa and means to mistake what is not the cause of
a given effect for its real cause. A second form is
called post hoc ergo propter hoc and means to infer
that one event is the cause of another from the
mere fact that the first occurs earlier than the
second. For our purposes, we will treat these two
forms as if they were exactly the same, simply an
argument from false cause.
- Example: "Seven months after Governor
Smith was elected, the state had a budget
deficit, the first in thirty years. Obviously,
Governor Smith is responsible." (How many times
have we seen this form of argument among
politicians? The two events in this case, the
election of Governor Smith and the current
budget deficit, are being linked as if a causal
connection existed between them. But this has
not been established. To argue that his election
caused the budget deficit, without considering
other causes and either showing such causes to
be true or false, is to argue
fallaciously.)
- Example: "John Doe was seen in the
vicinity of the broken window at about the time
that it was broken. Therefore, John Doe must
have broken the window." (Of course, on the face
of this argument, no such conclusion can be
drawn. John Doe may have broken the window (he
is the cause, the broken window is the effect)
but that is not established by the mere fact
that he was in the vicinity. A causal link
between John and the broken window must be
established on other grounds, such as an eye
witness or overwhelming circumstantial
evidence.)
- Example: "As television watching has
increased over the last ten years, so has the
crime rate. The more TV people watched, the more
crimes they committed. Therefore, we can say
that watching television causes crime." (This
form of argument is very common today. Although
this particular example shows clearly the
fallacy involved, many arguments of this type
escape criticism because they are so slickly
presented. Study the next example.)
- Example: "The divorce rate in America
has been climbing steadily. At the same time,
the number of juveniles getting into trouble
with the law has shot up. Something must be done
about the divorce rate since it is causing such
a rapid increase in juvenile delinquency." (Does
this argument sound familiar? Now, there may be
a relationship between the divorce rate and the
increase in juvenile delinquency. But, on the
face of the example given, no causal connection
has been established. We need to be careful
about assigning cause merely on the basis of two
events occurring at the same time, or two events
which appear to happen sequentially. The rise in
juvenile delinquency could be merely
coincidentally related to the divorce rate.
Given the circumstances of the argument, it
could just as well be argued that juvenile
delinquency caused the increased divorce rate.
But this, as given, commits the false cause
fallacy also.)
We must always keep in mind the difference
between cause and correlation, which are quite
different relationships. We must also consider the
possibility of coincidence. This is precisely why
it so often is difficult to arrive at what is true
and what is false.
Fallacy of
Accident
This fallacy is sometimes called the fallacy of
sweeping generalization and occurs frequently in
political speeches, discourses about morality, and
other discussions of particularly sensitive topics.
In a fallacious argument of this type, a general
rule is applied to a particular situation to which
the rule was not intended to apply.
- Example: "Money is the root of all
evil. Therefore, you should not give a reward to
the person who returns your lost wallet."
(Assuming the truth of the initial premise,
which most of us actually do not, it was never
meant to cover a particular case such as a
reward to a person returning a lost wallet. The
"moral" principle stated in the initial premise
was meant to apply to cases where money -- or
the love of such -- led to acts which are
clearly immoral or unethical. So here a general
rule is misapplied to a specific case.)
- Example: "Since tennis is such a
healthful exercise, John Doe should do more of
it because it will be good for his heart
condition." (Well, in fact, tennis may be
dangerous to John Doe because of his heart
condition and his physician may have advised him
against such exercise. There is no doubt that
generally speaking tennis is healthful exercise.
But that does not mean this health rule applies
to everyone regardless of circumstances. Study
the next example.)
- Example: "Recent scientific studies
have shown that moderate drinking of red wine
may decrease your chance of getting a heart
attack. So everyone should drink a glass of red
wine each evening with dinner." (As of this
writing, there are reports of scientific studies
which do show a positive relationship between
moderate amounts of red wine and a lessened
chance of heart attack. But should everyone
begin including red wine in his or her daily
diet? How about the alcoholic? How about those
with religious objections to alcohol? How about
small children? Enough said.)
An argument of the above kind has two parts to
it and these need to be examined. The first part is
the general rule, usually occurring in the initial
premise. The second part is the particular case,
usually referred to in the conclusion. There is an
easy way to expose this fallacy. First, isolate the
general rule and state it clearly. Second, show
that such a rule cannot be applied to this
particular case being cited. For instance:
- Yes, tennis is a healthful exercise -- if a
person's health allows it.
- Yes, moderate drinking of red wine may be
beneficial -- if you aren't an alcoholic, or
have religious objections, or are not a
child.
Let's consider one final example which has been
controversial. According to the Second Amendment of
the U.S. Constitution, citizens of this country
have the right to bear arms. There are some people
who argue that this right cannot be subject to
government control. Consider this argument:
- "Everyone has a right to bear arms, that is,
to own a gun. Therefore, even though James Smith
has been declared insane, the government has no
right to take away his gun."
The first premise in this argument is a general
constitutional principle which is widely accepted.
But does this principle apply to the particular
case of James Smith? Or should we say:
- Yes, every citizen has a right under the
Constitution to own a gun -- if he isn't insane
(or a convicted felon, for that matter).
The lesson here is that we must be careful about
stating general rules as absolutes with no
exceptions. And we must be cautious about applying
general rules to specific cases. This, by the way,
does not mean that all morality is "relative."
Moral principles are another matter. Consider the
following argument:
"Killing another human being is absolutely
immoral. Therefore, Jane Doe should not have killed
the man who attacked her even though he had a
deadly weapon and intended to use it against
her."
The first premise in this argument is a general
moral principle which most of us fortunately
accept. But does this principle apply in this case?
Or should we say:
- Yes, killing another human being is wrong --
unless you are defending yourself against deadly
force.
This exception is, of course, embedded within
our concept of jurisprudence.
The Hasty
Generalization
This is another all-too-common fallacy. It is so
easy to make. This fallacy involves the formation
of a generalization on the basis of observations of
a sample that is unrepresentative or too small. The
generalization is based on exceptional, or
specially selected, rather than typical, or
randomly selected cases. The perpetrator is using
insufficient evidence or an isolated example as the
basis for a widely general conclusion.
This fallacy is not committed just by ordinary
unsophisticated people. Cases can be cited where
trained empirical scientists have fallen into this
trap. The same can be said for the media. How often
have we seen people in the media jump to a general
conclusion about some event or some phenomenon with
little sufficient evidence to justify the
generalization?
- Example: "None of my grandchildren
play a musical instrument. It must be that young
people today don't care about music anymore."
(The premise may be true. My grandchildren may
not play a musical instrument and this is a
particular case. We cannot, however, draw a
general conclusion from this particular case
which applies to all cases, that is, all young
people.)
- Example: "We know the effect that
alcohol has on those who drink to excess.
Therefore, we can state that all liquor is
harmful and we urge that its sale and use be
forbidden by law." (This, of course, was the
main argument used to implement the disastrous
policy of Prohibition in the United States. The
argument, regardless of what one thinks about
alcoholic beverages, is fallacious. It is to
jump to a conclusion, a generalization, based on
atypical or unusual cases. There may be other
valid arguments for prohibiting alcohol, but
this is not one of them.)
- Example: "I had a bad time with my
former wife. From that I've learned that all
women are no good." (Do we even have to explain
this example of hasty generalization?)
Most of us may not like to think about this, but
it is probable that a great many of our prejudices
are the result of hasty generalizations. How many
times have we heard statements similar to
these?
- "I served with a few Blacks during the war.
Boy, I can tell you that all blacks are just a
bunch of lazy people who don't care about a
better life."
- "I knew a Jew and all he cared about was
money. That's all Jews are, just a bunch of
money-grubbing misers."
- "My neighbor was a Catholic. All he did was
drink alcohol and force his wife to have babies.
Catholics are disgusting. They just want to have
large families so they'll become the majority
and take over the country."
- "These Fundamentalist Christians are
terrible. I know a couple and they just want to
ram their religion down my throat at any
cost."
All of the above statements are examples of
hasty generalization. The person making the
statement has drawn a conclusion based on a few
atypical cases. This fallacy is committed when we
fail to take account of facts that are of such
significance that their consideration would require
a rational person to reject our conclusions.
Furthermore, we must not only consider evidence
that supports our argument, but also consider
evidence to the contrary.
The Complex
Question
This fallacy involves asking a question which in
reality is a composite of several questions,
demanding a single answer, and then applying that
answer to both the explicit question and the
unasked questions contained within it. This fallacy
is also known as the loaded question, the leading
question, and the trick question.
The component questions within a complex
question demand independent consideration. The
person asking a complex question obscures the real
issues involved and, in demanding a single answer,
implies a spurious simplicity. Beware of such
complex questions and demand that such a question
be "divided" into the simpler questions which make
it up. Then you can feel free to answer each simple
question independently.
- Example: Tax Man -- "Do you still
cheat on your income tax?" Taxpayer -- "No." Tax
Man -- "Aha, therefore in the past you have
cheated on your income tax."
- Example: Prosecutor -- "Have you
stopped beating your wife?" Defendant -- "Yes."
Prosecutor -- "Aha, so you admit you have beaten
your wife in the past!"
- Example: Interviewer -- "Are you
still a heavy drinker?" Interviewee -- "No."
Interviewer -- "Aha, so you were a heavy
drinker."
Each of the questions above contain an assumed
answer to a previous question. The unasked question
in the first example is: "Have you ever cheated on
your income tax?" In the second: "Did the defendant
ever beat his wife?" In the third: "Was the
interviewee ever a heavy drinker?" Answers to any
complex question should be withheld until the prior
or implied question is answered.
The above situations may simply be accepted as
harmless humor by many. But the complex question
can lead to serious consequences in certain
contexts. Consider this trick question if asked in
a court of law:
- "What did you use to wipe your fingerprints
from the gun?"
What do you say? If you answer, "Nothing," you
have admitted your fingerprints are on the gun.
This complex question should not be answered until
the implied question is answered and that is: "Were
your fingerprints on the gun?" The answer, "No,"
would safely eliminate the complex question
altogether. The answer, "Yes," of course, would put
you in the proverbial hard spot. Incidentally, this
question would likely not be permitted in a court
of law just because it is a complex question.
But suppose you are brought to the police
station to be interviewed regarding a robbery. The
lead detective is questioning you:
- "How long had you contemplated this robbery
before you carried it out?
There would be no bar to this type of question
during a police interrogation. If you answered, "I
didn't," you would be admitting guilt. If you
answered otherwise, you would also be admitting
guilt. The unasked, implied question is: "Did you
do the robbery in the first place."
So -- beware of complex questions.
The
Irrelevant Conclusion
This fallacy, also called ignoratio elenchi,
occurs when a person attempts to disprove a
conclusion by presenting information that merely
establishes another conclusion rather than refuting
the one under criticism. This is often used because
they are more persuasive and compelling than those
which present pertinent information or evidence. In
essence, the two parties in such a debate are
arguing past one another.
This is a particularly deceptive fallacy.
Sometimes it is referred to as ignoring the issue,
befogging the issue, or the "red herring." The
reason it can be so deceptive is that it often does
prove a conclusion although not the one under
debate.
- Example: John -- "All persons who
kill a police officer should die!" Sam --
"Murder, especially the murder of a police
officer, is an awful crime, but the death
penalty is cruel and unusual punishment and,
therefore, forbidden by the Constitution." John
-- "My brother was a police officer who was
killed during a bank holdup!" (There are two
different issues here. Capital punishment is one
issue and John's brother's murder is the
another. Sam and John are talking at
cross-purposes.)
- Example: "I fail to see why hunting
should be considered cruel when it gives so much
pleasure to many people and employment to even
more." (Whether hunting gives pleasure or
employment to people is irrelevant to whether
hunting is cruel to animal. If that is
irrelevant, then the argument that hunting is
cruel has yet to be debated. This argument
avoids what it is supposed to disprove, that
hunting is cruel to animals. It proves what has
not been argued, that hunting is advantageous
for people.)
The fallacy of irrelevant conclusion may have
dire consequences in certain situations. For
instance, a prosecutor trying a murder case may
argue successfully that a murder is a horrible
crime and may prove that conclusion without
difficulty. But if the prosecutor (or the jury)
infers from such an argument that the defendant is
guilty of the murder, the prosecutor (or the jury)
is committing the fallacy of irrelevant conclusion.
The question at point is whether the defendant is
guilty, not whether the murder is a horrible
crime.
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