Detecting Fallacies in Arguments
The ability to evaluate arguments presented in a text is one of the necessary
skills that a critical reader should develop.
In a previous issue of our Critical Thinking in Reading newsletter we have
discussed arguments and listed some important techniques for identifying and
evaluating arguments in a written text. We have defined an argument as a
collection of some supporting statements (premises) being used to justify
another statement (conclusion). We also identified two basic kinds of argument
- inductive and deductive.
Now, we discuss another vital component in evaluating arguments -
identifying fallacies. A fallacy can be simply defined of as an
incorrect pattern of reasoning in an otherwise logical argument. It
means that an argument can be valid (i.e. one where the conclusion
follows from the premises), have true premises, and even have the true
conclusion - but still one of the many known fallacies may have appeared
along the way! Consider the following example:
Example of a fallacy
How many times have you heard one of your friends say
"Nissans (Chevrolets, Fords etc.) are terribly unreliable! I owned one and it
broke down on me at the worst possible moment . I am never buying one
Let us analyze this argument. The emotional component of your friend's
willingness not to buy a car that arouses negative associations is
quite understandable. However, you are invited to conclude that millions
of cars of a certain manufacturer are .terribly unreliable. just because
your friend had one bad experience. Obviously, this is unreasonable for such a
conclusion. Also, by providing the information that the car
broke down "at the worst possible moment" the speaker hints that he or
she might be overreacting because of the inconvenience.
So, after all this, are Nissans unreliable? We can only conclude that we do not
have enough information to make a judgment in this case. The fallacy
is one of 'hasty generalization' - reaching a conclusion on the basis of
As you can see from the above example, fallacies do not mean that the conclusion
made was either true or false. But, even if the conclusion is true, the danger
of not recognizing a fallacy is in believing that an argument carries more weight
than it should. Here is another example of a fallacy.
"During our road trip, we stopped three times in Kentucky to fill up with gas.
On every occasion, the service station attendant had lots of missing teeth.
One of them refused to accept my Amex and insisted that only cash was good
enough. I was so angry! I tell you, we need to do something about these
toothless yokels that infest Kentucky!"
The fallacy above is that out of the scanty evidence of a few people with
missing teeth, and one person who refused a credit card, we hear the conclusion
that 'toothless yokels infest Kentucky'.
Well, here is another dental argument about Kentucky, but avoids the fallacy of
hasty generalization. by using a more credible source of information.
"According the world health organization, an extensive survey of all states in
the USA found that Kentucky scored the highest percentage of missing teeth. In
fact, over 43% were completely toothless. It is clear that Kentucky is
afflicted by poor oral hygiene."
Exploring some common fallacies
Let us consider some common fallacies found in written sources, and look
at ways of detecting them and dealing with them.
Loaded Questions (also known as "complex questions")
Example: One example of this fallacy is the question, "Have
you stopped stealing?" The question is formulated as a yes/no
question, and any direct answer implies that you have indeed been
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How to deal with it: Remember that complex questions cannot be answered
in a simple yes/no way, but require a complex answer. So, a reasonable
way of denying the fact that you have been stealing in our
example is: "I wasn't stealing, so I can't stop something I
In written sources, loaded questions can often be found in interviews,
polls and surveys. As a respondent or interviewee, you should always aim
to recognize and expose these types of questions. It is also important to
recognize how loaded questions that go unnoticed could taint a report or
survey and lead to inaccurate conclusions.
Example: The current government is renowned for its sound economic
management. After just two years under their direction, unprecedented
economic growth has been recorded.
This fallacy assumes that just because one event comes before another
event, the first event must have caused the second. Just because the
government took control two years before the growth, it doesn.t necessarily
mean that the government caused the growth. Many factors, such as the
state of the global economy, political situation or even the long-term economic
policies of the previous government could have influenced the economic
The following two Murphy's laws provide a simple and humorous
explanation of why post-hoc reasoning is faulty:
How to deal with it: When you suspect post-hoc reasoning, ask yourself these
- If you wash your car, it will rain.
- Washing your car to make it rain doesn't work.
Which of these sentences has post-hoc reasoning?
- Is there evidence that the effect would have occurred even if the
cause did not occur?
- Could it be that the effect was caused by other causes and not the
- It's no wonder your car got burgled, you were visiting Dallas. Dallas has the
highest crime rate in the USA..
- In 1964 in Alaska, an earthquake measuring 9.2 on the Richter scale devastated
Prince William Sound. A giant tsunami ripped through Canada and the USA, a
green killer wave measuring 67 meters in height. This enormous event changed
the geology of the USA. The USA has not been the same since; we are still
feeling the ill after effects of this giant quake; earthquakes, tornados, and
global warming. And there.s more to come!.
Both of the sentences above have post-hoc reasoning. A car can be burgled
even in the city with the lowest crime rate in the world. The second example
discusses a giant earthquake, and suggests that as a result of this event,
follow-on events are happening 40 years later including tornados and global
warming. It doesn't provide any arguments as to why the earthquake in 1964
has caused the follow on events.
This type of fallacy often occurs in newspaper and magazine articles,
advertisement, election campaign materials, as well as various reports
and studies. Because cause does come before the effect, this fallacy
is often difficult to spot. That is why it is important to make
a conscious effort to carefully consider all available facts whenever
a "cause-effect" relationship is suggested.
It is important to train yourself to identify fallacies when you do your
daily reading. Apart from being a great brain workout, this exercise has
an immense practical value in making you a better critical reader. We
will discuss some other common fallacies in a future issue of this