Logical Fallacies

STUDENT HANDOUT
LOGICAL FALLACIES
Explanation of Logical Fallacies * What is logic? * Logic is reasoning that is conducted according to strict principles.

* How is logic related to expository writing? * When you write an expository essay, you are using logic to provide the layers of proof for your statements. * You are proving your thesis when you construct your topic sentences. * e.g., answering the “Why”, “How”, “What are they” questions about the thesis * You are proving your topic sentences when you construct your primary supports * e.g., answering the “Why”, “How”, “What are they” questions about the topic sentence * You are proving/fleshing out your primary support when you construct your secondary supports. * e.g., answering the “What do you mean”, “Tell me more”, “Why”, “How”, “What are they” questions about the primary supports * You can think of logic/reasoning as the answers to the questions that prove the thesis, topic sentences, and primary supports.

* What is a logical fallacy? * A logical fallacy (a.k.a. rhetorical fallacy) is an error in reasoning. In expository writing, it is the wrong answer to one of the questions. There are many reasons why people come up with the wrong answers. Some of the most common reasons are listed below (see Different Types of Logical Fallacies). * Logical fallacies in writing signal two assumptions about the writer: * The writer is not honest; * The writer is not smart.

* Uses for Logical Fallacies * Writers of advertisements, editorials, and political propaganda will use logical fallacies to their advantage.

Different Types of Logical Fallacies * Circular Logic (a.k.a. smoke and mirrors) – an argument in which the writer supports his/her position by partially restating it. * Another effect of academic failure is negative feelings. Depression, resulting from academic failure, will lower a person’s self-esteem. Similarly, depression will increase based a person’s despondency about the lack of employment options available to them because of their academic setbacks. * The topic sentence states that one result of academic failure is negative feelings. Thus, the reader will expect the writer to explain HOW academic failure causes negative feelings. The reader may also expect the writer to explain WHAT the negative feelings are. Depression is one type of negative feeling. However, the writer does not show how academic failure causes depression. Instead, he/she states that depression will lower a person’s self-esteem, which is very similar to depression. In the next sentence, the writer states that depression will increase based on a person’s despondency about the lack of employment. Because despondency is the same as depression, the writer has said absolutely nothing by making that statement. Moreover, he/she has lost the direct connection between academic failure and negative feelings when he/she chose to include employment.

* Non Sequitur (a.k.a. Lying) – “It does not follow.” A statement in which the conclusion does not logically follow the premise. * Another problem with the current drinking age of 21 is that it results in abusive consumption. One way it results in abusive consumption is the long anticipation for the appropriate age, which is likely to create excessive drinking after it becomes available. A lot of young people who reach the legal age tend to go overboard when they are finally able to drink whenever they want. They do not care about their limits and the consequences of irresponsible drinking because nobody can tell them not to drink. As a result, they end up drinking too much. Another way it causes abusive drinking is that teenagers under the age of 21 are driven by the temptation of illegal activity. The age limit has not eliminated drinking for people under 21. Instead, it has pushed them to do it in private environments, where they can hide from parents and the law. * The topic sentence specifies that the current drinking age results in the abusive consumption of alcohol. In order to prove this topic sentence, the writer would have to answer the HOW question with regard to the topic sentence. To be specific, HOW does current drinking age lead to the excessive consumption of alcohol? Although the writer does answer the question, he/she provides incorrect answers. First, the writer contends that people who have to wait until a certain age to drink alcohol go overboard because they’ve waited so long. This is not true! People who are unable to control their behavior are likely a certain personality type, not a certain age. Even if the age were to change to eighteen (as the writer of this paper suggested), people with this particular personality type would still have the same problem. Second, the writer contends that people under the age of 21 are driven by a temptation to participate in illegal activity. Again, this is not true! People who have an affinity for illegal activity can be any age. Unless the writer can cite several reputable studies that confirm his/her claim, it is entirely false.

* Slippery Slope (a.k.a. Exaggerating) – assuming that one thing will cause something extremely drastic. * Smoking marijuana will lead to cocaine addiction. When young people smoke marijuana, they normally become addicted to the feelings of pleasure that they derive from the activity. Once people become used to those feelings, they will seek something stronger. Eventually, they will try harder drugs. Cocaine is one of the harder drugs and very addictive. As young people seek a harder drug that will allow them to feel the “high” that they seek, they are likely to try cocaine and, unfortunately, become addicted. * The topic sentence makes a claim that is REALLY PRESUMPTUOUS! What evidence does the author have that people normally become addicted to marijuana? Has a study proven that? Even if some people do become accustomed to the feelings of pleasure associated with marijuana, it is a big assumption to determine that they will “need something stronger”. It is an even bigger assumption to determine that they will try cocaine as the “stronger” drug.

* Ad Hominem (a.k.a. low blows) – a personal attack on an opponent rather than dealing logically with the issue itself * Another reason why teenagers should not be allowed to drive is because they do not make good decisions. Teenagers have not developed the social skills needed to be courteous drivers. They are self-centered people whose negative attitudes are clearly seen in the ways that the currently behave while on the road. * The topic sentence states that teenagers do not make good decisions. The writer’s first primary support does begin to prove the TS because it answers the WHY question about the TS. However, the secondary support is erroneous. Instead of providing more evidence about the PS (by answering one of the appropriate questions associated with it), the writer insults teenager by saying they have negative attitudes and poor behavior.

* Red Herring (the hidden ammunition) – an argument in which the writer introduces an irrelevant point * Another way that illegal immigrants contribute to the economy is by working. Despite doing back-breaking work, many of the immigrants are barely paid minimum wage. People who hire illegal immigrants can pay them lower wages than a regular U.S. worker because the illegal immigrant has no rights. Employers who hire illegal immigrants know they can save money if they hire them, and they know the immigrants will not tell anyone because of the fear of being deported. * The writer has lost his/her focus. The topic sentence specifies that the illegal immigrant workers contribute to the economy. Thus, readers will expect to see the different ways that the workers do that (e.g., the jobs they obtain and HOW those jobs contribute to the economy, perhaps the goods they buy and HOW they contribute to the economy). However, the writer spends the entire paragraph focusing on how the illegal immigrant workers are unfairly treated. Their unfair treatment has nothing to do with their contribution to the economy.