Logical Fallacies

What They Are, and How to Avoid Them

Avoiding Logical Fallacies - What They Are, and How to Avoid Them

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Even if it looks like a duck, and quacks like a duck, it may not be!

"In a study designed to test the effects of pleasant imagery on motivation, employees were shown images of baby animals and beautiful nature scenes for their first five minutes at work.

"Amazingly, results showed a 10% leap in profits in the first quarter and record earnings over the course of a year. 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.

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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.

Infographic

You can see our infographic on Logical Fallacies here:

Logical Fallacies

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?
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Comments (15)
  • Over a month ago Michele wrote
    Hi rlagill,

    Thanks for the reference to the site on logical fallacies. Our members will appreciate learning more about to recognize them and not be fooled by others who use them.

    Michele
    Mind Tools Team
  • Over a month ago rlagill wrote
    If you find logical fallacies fascinating, check out: https://yourlogicalfallacyis.com/
  • Over a month ago BillT wrote
    Hello rbuckham,

    Thank you for the positive feedback and for the reference to the Ladder of Inference article. These two articles tie together very nicely.

    Bill
    Mind Tools Team
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