Logical Fallacies

"I read an article yesterday about a study by a famous academic designed to test the effect of pleasant imagery on employee motivation. Employees were shown images of baby animals and beautiful nature scenes during their first five minutes at work. Amazingly, the company where the study was conducted had a 10% jump in profits that quarter and over the year they posted their highest earnings yet. So showing employees pleasant images is a great way to increase their motivation and improve productivity."
What do you think about the argument you just read? Do you believe the conclusion?
In fact, the argument presented above contains a number of logical fallacies (according to the Merriam-Webster Dictionary, a fallacy is "an often plausible argument using false or illogical reasoning".) Don't worry if you believed the conclusion: The passage contains some very common and effective tactics for circumventing reason and logic. You'll learn what these are a little later!
Being able to discern a valid argument from
a false one is an important skill. There are lots of people out
there hoping to get you to believe what they are saying, despite
having no proof for their message. And there are also many people
whose motivation is less suspect, but who nevertheless present
illogical reasoning, because they fail to understand the implications
of the facts at hand.
Either way, if you are aware of what to look for to determine if
an argument is sound or not, you can avoid falling victim to
invalid arguments.
The Basis of an Argument
To understand how to spot logical fallacies, you should have a
basic understanding of the mechanics of an argument. An argument
in logic is a set of statements where one statement is inferred
from the other or others. There are two types of statements:

Premises – statements offered to provide
evidence for the conclusion of an argument.
Conclusions – statements that are inferred
from the evidence provided.

For an argument to be valid or logical, the
premise statements must provide full support for the conclusion.
They do this in one of two ways:
1. Using Deductive Reasoning

Here you start with premises of a general nature, and reach a specific
conclusion.
Example:
Premise 1: Trucan Supply decided that to minimize redundancy costs, it would limit its layoffs to the New York facility only.
Premise 2: Tom received a lay-off notice.
Conclusion: Tom works at the New York facility.
2. Using Inductive Reasoning

Here you start premises that are specific,
and reach a generalized conclusion.
Read our article on Inductive Reasoning for more on this.
Example:
Premise 1: April promotions over the last five years have increased sales by 15%, on average.
Premise 2: Over this period, summer promotions have not produced any measurable increase in sales.
Conclusion: To increase sales, it is better to have this year's promotion in April rather than in the summer.
Logical Fallacies
A logical fallacy is a statement that might appear at first sight to be true but, after applying the rules of logic, is not. Logical fallacies can often be attempts to mislead people, and get them to
believe something that is not necessarily true.
If you use a logical fallacy you discredit yourself as you appear dishonest or foolish. You don't want to fall victim to a logical fallacy either, as the false conclusions might cause you to make
decisions you later regret.
Defending yourself from logical fallacies requires being aware of the most common types and knowing how to avoid them. We'll look at some of these next.
Common Fallacies
Remember the example at the start of this article? It relied on three of the most common forms of logical fallacy:
Appeals to Authority – this is where you rely on an "expert" source to form the basis of your argument. In that passage the apparently expert sources is "a famous academic." Mentioning an academic conjures expert authority and rigorous research backing results. And using a real name would be even stronger. When you're on the lookout for fallacies, it's important to remember that
name-dropping is not sufficient evidence to support the argument.
False Inductions – often called "non sequitur" for the Latin translation "it does not follow."
This fallacy gets you to infer a causal relationship where none
is evident. Just because something happened before something else
does not mean there is a logical, causal link between the two.
Showing the pleasant images may or may not be linked to the company's
improved performance. There are a number of other factors that
could have been involved. Whether or not the pleasant images had
an impact is not demonstrated in the passage at all.

The Reification Fallacy – this type of fallacy relies on taking a
hypothesis or potential theory and presenting it is as a known
truth. Here, while there is much evidence that employee motivation
improves individual performance, this is still just a theory.
There are many other factors that contribute to performance
improvement. It is incorrect to conclude that increased motivation
must result in increased productivity.
Some other common types of logical fallacy include:
The Slippery Slope – this is an argument that relies on thinking
that "the worst that can happen" will actually come true. Somehow
the direst consequence will result if a certain action is taken or
change is implemented.
Example: "If we allow Susan to leave early, soon we'll be giving
everyone Friday afternoon off." If you step back, you can see that
it's illogical to conclude that you will give absolutely everyone
an afternoon off every single week just by allowing one employee
to leave early one time.
The Bandwagon Fallacy – here, someone is led to believe in an idea
or proposition simply because it's popular or has lots of support.
The fact that lots of people agree with something doesn't make it
true or right.
Example: "We surveyed all the customers in the store and they all
agreed staying open 24 hours would be a great idea. We need to put
together a 24-hour schedule as soon as possible." Who were these
people? Would they actually purchase something from the store at
2am? What are the costs versus the benefits of such a plan? These
are the types of questions you have to ask before you can draw any
kind of conclusion from the informal survey results.

Closely associated with the bandwagon
fallacy is an Appeal to Tradition fallacy. Here the argument
centers on something that has always been done or is a
widely accepted practice. For instance, "We've always hired
the CEO from among the ranks. If we look outside there will
be too much dissention and discord."

The False Dichotomy Fallacy – making an
"either or" argument. To create this logical fallacy you provide
only two options and force a choice. In fact, neither choice may
be the best, but the argument makes it appear that the favored
option is the only feasible one.
Example: "We as the Board can either
choose to approve this IPO or we can suffer a slow death at the
hands of our competitors." Here, there are certainly options
other than taking the company public that could be considered.
And is raising capital even the answer to improving or maintaining
the company's competitive position?
The Straw Man Fallacy – this is a technique where a false argument
is created and then refuted. The counter argument then is believed
to be true. By deliberately misrepresenting an opposing position
and then knocking it down, you falsely build your own position.
Example: A politician is calling for tax cuts to promote more
spending and spur the economy. Her opponent makes this statement,
"What this will do is make the wealthy wealthier, so they can
drive around in four luxury automobiles instead of two, have two
vacation homes instead of one, and send their over-privileged
children to private boarding schools instead of schools in their
home town." By making it sound like the politician wants to cut
taxes only to take care of the wealthy, her opponent has knocked
down her position much more easily than if he had tried to deride
a policy of cutting taxes across the board.

Note:
Don't confuse a straw man argument
and a straw man proposal . With a straw man proposal you
start with a half finished idea and poke holes in it
deliberately to get to a better final product. Unlike a
straw man argument, a straw man proposal is an effective
process when used with clear and honest intentions.

Observational Selection – this happens
when you draw attention to the positive aspects of an idea and
ignore the negatives. You are trying to confirm your belief by
providing only half the story.
Example: "I know our television ads are more effective than radio.
The numbers show that we hit twice the audience with TV and our
focus groups remember our TV ad 38% more than the radio slot."
What this argument fails to address is the cost and return on
investment of television ads versus radio. Does the 38% increase
in retention translate to sale conversions? What percentage of
radio listeners versus TV watchers actually buy the product?

The Statistics of Small Numbers fallacy is a similar concept. Here you take one observation
and use it to draw a general conclusion. "I would never
use Gaudi Brothers to supply our paper products. My wife's
company used them and they short-shipped products and back-ordered
them." In fact, this opinion is based on one bad experience,
and doesn't necessarily mean the company is unreliable.
Perhaps the purchasing company was late submitting orders,
or late paying their invoices. These would contribute to
less than stellar customer service on the part of Gaudi
Brothers.


Key Points
Logical fallacies are common traps into which
people fall. Sometimes fallacies are created deliberately to deceive.
Other times they are present innocently because the person making
the argument hasn't sufficiently thought through his or her logic.
But whatever the motivation behind the logical
fallacy, if you make or believe one. it can discredit you. Be
aware that these lapses in reasoning occur quite commonly, and
remain alert to them. By questioning everything and constantly
checking the rationale of arguments you hear and present, you
should be able to avoid logical fallacies and really see the truth
of the matter.

Apply This to Your Life
Next time you're evaluating an argument or constructing one
of your own, use these questions to help you determine
whether what you are being told, or what you're about to say
is logical and rational.

What can you directly deduce or induce
from the premises presented?
Can you come up with at least one rival
but plausible conclusion?
Can you make a direct connection between
the facts and information given, and the conclusion that
is presented?
Are there independent sources of information
that can confirm the facts you've been given?
Are you too attached to the hypothesis
because you have been involved in generating it?
Have you debated the evidence and conclusion
with other people and from all different viewpoints?
Are you relying too heavily on a single
expert's authority or a single source of data without
third party confirmation?
Is the information being presented
clearly, with little jargon or superfluous information
to distract your attention?
What assumptions are you relying on
to support the argument? Are these assumptions valid or
do they come from personal bias?