On the other hand, what if you have been study-
ing and getting good grades and there is a test coming
up? You are busy with other things and don’t study for
it. You get a D on the test. The argument goes like this:
Every time I have a test coming up, I study
for it and get good grades. This time, I
didn’t study, and I got a D.
If you don’t want to get more Ds in the future, you
will want to know what caused the bad grade, pre-
venting the unwanted result by preventing the cause.
What is the key difference in the argument? Studying.
In this case, the key difference means if you don’t want
bad grades, you must study. Remember that in order to
determine cause, an argument must be formed that
looks for a key difference between two otherwise sim-
ilar events.
Here is another example:
You had a stomachache on Thursday and
you are trying to figure out why. Every
morning for breakfast you eat bran cereal
with skim milk and a banana. But, Thurs-
day you were out of milk and had toast
for breakfast instead. By midmorning, you
had a painful stomachache. You picked up
milk on the way home from work and had
your usual breakfast on Friday. The stom-
achache did not occur on Friday. Nothing
else in your routine was out of the
ordinary.
What caused the stomachache? Chances are, it
was the toast you ate for breakfast. It is the key differ-
ence. Every morning when you eat your regular break-
fast, you feel fine. On the one morning when you ate
toast instead, you got a stomachache. Every example is
not this easy, however. Sometimes the key difference is
difficult to spot and requires an inference based on the
information presented in the argument.
Real-life situations can get complicated. Our lives
and the world around us are affected by thousands of
details, making the finding of one key difference diffi-
cult. That said, if there is a strong likelihood of causa-
tion and there are no other obvious causes, you can
make a convincing causal argument. But you need to
have the following:
■The effect must occur after the cause. This
sounds like common sense, but there are many
arguments that place the effect before the
cause.
Example
You are blamed for a computer problem at
work. However, you did not use the computer
until after the problem was detected. The argu-
ment against you has no strength.
■You need more than just a strong correlation
to prove causation. Coincidence can often
explain what might first appear to be cause and
effect.
Example
Every time you wear your blue sweater, your
team wins the game. Can you determine that if
you always wear the sweater, your team will
always win? The answer is no, because there is
no causation. Nothing about your wearing the
sweater could have caused a certain outcome in
a game.
Practice
Look for causation in the following scenario.
Yesterday, I pulled out of a diagonal park-
ing spot, and was starting to turn my
–INDUCTIVE REASONING–
108
wheel and move forward, when another
car backed out of a spot behind me. She
drove right into me, smashing my left rear
door with the corner of her bumper. The
other driver told the police officer that I
hit her. But he agreed with me that it was
her fault, and wrote down why on the
police report.
What did the police officer write? Circle all that
could apply.
a. Drivers must wait their turn if another car is
already pulling out of a parking space behind
them. It is clear that the first car was already out
of her space when she was hit on her door.
b. It is impossible to hit the corner of someone’s
bumper with your rear door when backing out of
a parking spot. It is possible to hit the rear door
of someone’s car with the corner of your bumper.
c. Speeding in parking lots is prohibited by law.
d. The other driver must not have been looking in
her rearview mirror, or she would not have
backed into the other car.
Answer
The probable causes of the car accident are a,b, and d.
While speeding in parking lots is never a good idea, it
was not a factor in this accident.
In Short
Inductive reasoning uses specific information that has
been observed or experienced, and draws general con-
clusions about it. To make those conclusions, it relies
on either (or both) past experience and common sense.
Because the conclusions can only state what is likely or
probable, there is a greater chance of error with induc-
tive reasoning as opposed to deductive reasoning. In the
next lesson, you will learn about specific ways in which
inductive reasoning goes wrong.
–INDUCTIVE REASONING–
109
You are always drawing conclusions from your observations. Pay attention to this inductive reason-
ing and evaluate your skills. Are you using common sense and/or past experience? Have you noticed
a key difference, or compared two similar events? Become a better user of inductive reasoning by
being aware of when and how you use it.
Skill Building Until Next Time
AN INDUCTIVE CONCLUSION is only as good as the quantity and quality of its premises.
There are a number of ways in which to create a strong inductive argument, and just as many
ways to create a weak one. The premises must contain enough evidence or the conclusion
will be what is known as a hasty generalization. If you claim cause and effect and there is not enough evi-
dence, you create a chicken and egg fallacy. If the conclusion you draw does not fit the facts, it is a fallacy
known as post hoc, ergo propter hoc.By focusing on parts of a whole and drawing a conclusion based only
on those parts, you create a composition fallacy.
It is important to understand how these fallacies work so you can avoid them in your own arguments
and recognize them when they are used by others.
LESSON Misusing
Inductive
Reasoning—
Logical Fallacies
LESSON SUMMARY
An inductive fallacy looks like an argument, but it either has two prem-
ises that do not provide enough support for the conclusion, or a con-
clusion that does not fit the premises. This lesson helps you spot them
so you are not taken in by their faulty logic.
15
111
Chicken and Egg (Confusing
Cause and Effect)
The age-old question,“which came first, the chicken or
the egg?” is used to describe dilemmas to which there
are no easy answers. In terms of logical arguments,
when you are not sure which came first, you could
make an error by confusing cause and effect. Just
because two things regularly occur together, you can-
not necessarily determine that one causes the other.
Chicken and egg is a fallacy that has the following gen-
eral form:
1. A and B regularly occur together.
2. Therefore, A is the cause of B.
This fallacy requires that there is no common
cause that actually causes both A and B, and that an
assumption is made that one event must cause another
just because the events occur together. The assumption
is based on inadequate justification; there is not enough
evidence to draw the causal conclusion.
A common example of the chicken and egg fal-
lacy is the relationship between television and movie
violence and real-life violent behavior. Many people
believe that violent behavior is the result of watching
TV and movie violence. Many others believe that peo-
ple are violent, and therefore they create, watch, and
enjoy violent programming. Does television violence
cause real-life violence, or vice versa? Or, is there no
causal relationship between the two? The simple fact
that some people are violent, and some entertaining TV
shows and movies contain violence, is not enough to
assert a connection.
How can you avoid the chicken and egg fallacy?
The fallacy occurs because the conclusion is drawn
without having enough evidence to determine cause
and effect. One way to avoid it is to pay careful atten-
tion to the sequence of events. If A happens after B, A
can’t cause B. Another way is to ask yourself if there is
anything else that could have been the cause. Think
about the evidence presented. Is it enough to draw the
conclusion?
Examples
■Many people who have lung cancer are smok-
ers. Having lung cancer causes people to
smoke.
■If you keep speeding, you will become a bad
driver.
■Last night I had a fever. This morning, I have a
cold and a fever. The fever caused the cold.
Practice
Which of the following is NOT a chicken and egg
fallacy?
a. Johnny Cash was famous. He was also on televi-
sion frequently. Johnny Cash was famous because
he was on television frequently.
b. I didn’t wash dishes all week. My dirty dishes
started to grow mold. If I don’t want mold grow-
ing on my dishes, I should wash them.
c. My boss really liked the work I did on my latest
project. I didn’t work as hard on the project as I
usually do. In order to make my boss happy, I
shouldn’t work as hard as I usually do.
d. Your grades went down this semester. You joined
a study group this semester. Your grades went
down because you joined the study group.
Answer
Choice bis not a chicken and egg fallacy, it is a logical
inductive argument. Choices a,c, and dare all exam-
ples of chicken and egg arguments. There is not enough
information in any of the premises to be able to draw
their conclusions. Either there is a common cause of
–MISUSING INDUCTIVE REASONING—LOGICAL FALLACIES–
112