Logical fallacies are errors in reasoning that are based on poor or faulty logic. When presented in a formal argument, they can cause you to lose your credibility as a writer, so you have to be careful of them.
Sometimes, writers will purposefully use logical fallacies to make an argument seem more persuasive or valid than it really is. In fact, the examples of fallacies on the following pages might be examples you have heard or read. While using fallacies might work in some situations, it’s irresponsible as a writer, and, chances are, an academic audience will recognize the fallacy.
However, most of the time, students accidentally use logical fallacies in their arguments, so being aware of logical fallacies and understanding what they are can help you avoid them. Plus, being aware of these fallacies can help you recognize them when you are reading and looking for source material. You wouldn’t want to use a source as evidence if the author included some faulty logic.
The following pages will explain the major types of fallacies, give you examples, and help you avoid them in your arguments.
The basic structure of all arguments involves three interdependent elements:
- Claim (also known as the conclusion)—What you are trying to prove. This is usually presented as your essay‘s thesis statement.
- Support (also known as the minor premise)—The evidence (facts, expert testimony, quotes, and statistics) you present to back up your claims.
- Warrant (also known as major premise)—Any assumption that is taken for granted and underlies your claim.
Consider the claim, support, and warrant for the following examples:
Claim: The No Child Left Behind Act (2001) has led to an increase in high school student drop-out rates.
Support: Drop-out rates in the US have climbed by 20% since 2001.
Warrant: (The claim presupposes that) it‘s a "bad" thing for students to drop out.
Claim: ADHD has grown by epidemic proportions in the last 10 years
Support: In 1999, the number of children diagnosed with ADHD was 2.1 million; in 2009, the number was 3.5 million.
Warrant: (The claim presupposes that) a diagnosis of ADHD is the same thing as the actual existence of ADHD; it also presupposes that ADHD is a disease.
Claims fall into three categories: claims of fact, claims of value, and claims of policy. All three types of claims occur in scholarly writing although claims of fact are probably the most common type you will encounter in research writing. Claims of fact are assertions about the existence (past, present, or future) of a particular condition or phenomenon:
Example: Japanese business owners are more inclined to use sustainable business practices than they were 20 years ago.
The above statement about Japan is one of fact; either the sustainable practices are getting more popular (fact) or they are not (fact). In contrast to claims of fact, those of value make a moral judgment about a phenomenon or condition:
Example: Unsustainable business practices are unethical.
Notice how the claim is now making a judgment call, asserting that there is greater value in the sustainable than in the unsustainable practices. Lastly, claims of policy are recommendations for actions—for things that should be done:
Example: Japanese carmakers should sign an agreement to reduce carbon emissions in manufacturing facilities by 50% by the year 2025.
The claim in this last example is that Japanese carmakers‘ current policy regarding carbon emissions needs to be changed.
For the most part, the claims you will be making in academic writing will be claims of fact. Therefore, examples presented below will highlight fallacies in this type of claim. For an argument to be effective, all three elements—claim, support, and warrant—must be logically connected.