Spotting Logical Fallacies

Learning Objectives

  • Evaluate logical fallacies in texts
A laptop with the words "fake news" on the screen.

Figure 1. Identifying logical fallacies is important as you analyze the credibility of the author and his or her argument.

When you evaluate an argument for logical fallacies, you consider what elements of the argument, if any, would cause an audience to believe that the argument is illogical or inappropriately manipulative. If you determine that these fallacies have been committed, you should question the credibility of the author and the legitimacy of the argument. If you employ these fallacies when making your own arguments, be aware that they may undermine or destroy your credibility.

Read the following passage and note where you see logical fallacies.


Passage: against the smoking ban

The University of Mississippi recently passed a policy banning smoking on campus. I am a smoker, and I have a lot of friends who are smokers, and we all agree that this policy should be overturned. This policy is framed in terms of health outcomes and promoting individual well-being, but the University has not instituted policies regarding many other behaviors related to health, such as exercising. Furthermore, the University does nothing to sanction other forms of air pollution, such as automobile exhaust.

Smoking is a right, and Americans have rights, so the smoking ban is wrong. What’s next? Will we ban potato chips and Cokes on campus? Will we force-feed broccoli and carrots to first-year students? People eighteen years old and up are adults and have the ability to make their own decisions regarding their health and habits. The policy also states, “All members of the university community share in the responsibility for adhering to and enforcing this policy.” That type of language asks students and faculty to be informants against each other.

A college campus is a place for free expression of ideas and behaviors. It’s simple: either we are a freedom-loving campus or we aren’t. I choose freedom, and I believe all of America’s veterans would agree with me. Perhaps the Chancellor has an ulterior motive for instituting the ban and is using smokers as a scapegoat.

Try It

Each question below will show you a section from the passage. Decide which logical fallacy best applies to the statement, or select “no fallacy.”

Sample Assignment

Let’s take a look at a hypothetical assignment to see if we can help Mateo to spot fallacies in his research. This is the assignment:

For our next project, you will be required to write an argumentative essay on a topic of your choice. Ideally, your topic should be related to your major, as this will give you an opportunity to explore issues you are interested in.

You must choose at least a relatively controversial issue because I want you to really investigate controversy and disagreement.

Your final essay should include at least six outside sources. Remember to look for sources that are credible and logical.

Mateo is a nursing major and has thought about what he might like to explore for his essay. He has decided he wants to write about the obesity epidemic in America.

His instructor is requiring some outside sources and Mateo has learned about the different kinds of sources he can use and what kinds of logical fallacies he should be aware of as he looks for quality, credible sources.

Mateo is ready to see if he can find the kinds of sources he needs and to make sure his sources avoid the logical fallacies. If Mateo uses sources that contain logical fallacies, he knows his credibility will be affected.

Mateo’s First Source

Mateo found a documentary on obesity in America. He is not sure about its credibility, however, as he heard one person in the documentary say this:

“As individuals, we need to address obesity. Since 1 in 3 Americans is expected to be obese in the coming years, Americans will be facing horrible, painful, difficult deaths associated with diseases caused by obesity.”

What type of fallacy is demonstrated in this passage?

Mateo’s Second Source

Mateo found a blog post from a person who seems to be a doctor. The doctor seems to have the right credentials, but Mateo read this and had some questions.

“Because children spend so much time playing video games, it is inevitable that they will become obese.”

What type of fallacy is demonstrated in this passage?

Mateo’s Third Source

Mateo found another documentary that looked interesting. In the documentary, one of the experts had this to say about the causes of obesity in America.

“It’s plain and simple. The obesity crisis is caused by too much food or too little exercise—or both. There’s not a lot of in between here.”

What type of fallacy is demonstrated in this passage?

Mateo’s Fourth Source

In one magazine article, Mateo found some information with an interview from a nutritionist who was making an argument that the chemicals and sugars put into processed foods were designed to make people eat more and would cause people to gain weight quickly. Later in the article, another expert disagreed and said this about the nutritionist:

“Basically, this idea gives people a pass. This nutritionist is saying it’s not your fault if you are obese that you have no responsibility in the matter. It’s not all the food companies’ fault.”

What type of fallacy is demonstrated in this passage?

Mateo’s Fifth Source

Mateo found a helpful website that presented a lot of different sides to the issue. This seemed great, but he noticed he would have to be careful about what he used because some of the “experts” quoted on the site were not presenting themselves in a credible way. One expert had this to say:

“The health ‘experts’ who point to processed foods as the root cause of this epidemic are missing the point and really are no better than the wacko ‘experts’ who tell us one minute that wine is good for us and the next minute it isn’t.”

What type of fallacy is demonstrated in this passage?

Mateo’s Sixth Source

Mateo conducted a personal interview with someone he thought might be a good resource, at least for one aspect of the debate. He interviewed a local activist who was working to bring local fruits and vegetables to poorer families in his community. This interview would provide an important perspective for his argumentative essay. However, he was worried when, at the end of the interview, the activist seemed to lose his focus and go off on a tangent.

“If we don’t fight against the big food companies and big agriculture, there is no telling where we might end up. If we keep going the direction we are going, we will end up with no choice, and pretty soon, we could have no food. When you are that specialized, you are just one step away from a blight that could lead to food shortages everywhere in the U.S.”

What type of fallacy is demonstrated in this passage?

Mateo’s Seventh Source

Mateo found one more source. This was another documentary a friend had recommended on the issue of obesity in America. The documentary was interesting and made some good points, Mateo thought. But, parts of it felt a little too “conspiracy theory” like, and Mateo wasn’t sure if he could really use this source. The narrator at one point said this about finding solutions to the obesity epidemic:

“Our government officials are not going to help us fight the food companies that poison us with their chemicals. Our government officials take campaign contributions from these big companies. If you think you can trust your government official to stop big agriculture, think again. Our government is too much connected with these evil companies.”

What type of fallacy is demonstrated in this passage?

Try It

Test your ability to spot logical fallacies in the following exericse.