Errors in Reasoning
Poor quality evidence and unreasonable warrants often lead to faulty conclusions. These errors in reasoning are often described as informal reasoning fallacies. Knowledge of these fallacies can help students form more powerful arguments and be better thinkers.

Hasty Generalizations
When people form opinions based on too little evidence or too few examples, they are making hasty generalizations. An example of this fallacy would be a person watching a story on the TV news about a woman cheating on welfare and assuming that most people on welfare are cheaters. Stereotypes are often the result of hasty generalizations.

Accident
This type of fallacy occurs when individuals base an opinion on the exception to a rule. For example, although people generally agree that killing other people is wrong, most agree that there are times, such as in defense of yourself or others, when it might be acceptable. Reasoning by accident would say that since killing in self-defense is not wrong, then killing in another kind of situation is not wrong.

False Cause
This fallacy in reasoning occurs when students think that because two events happen one right after another, one causes the other. Both events could be caused by the same third event or they could just coincidentally happen at the same time. Many superstitions come from this kind of reasoning. “When I wear my lucky shirt, I always do well on tests.” 

False Analogy
Comparing two similar concepts or ideas through analogies can be a powerful tool for understanding unfamiliar concepts. Faulty reasoning comes into play, however, when unreasonable comparisons are made. For example, there are similarities among the American Revolution, the French Revolution, and the Mexican Revolutions, but making judgments about one might be faulty since there are also significant differences among the three revolutions.

Poisoning the Well
This strategy is used by people who are so committed to a particular point of view that they discount any evidence that conflicts with their views. A high school student, for example, may say that Shakespeare’s plays are stupid and refuse to acknowledge that millions of people have enjoyed them for centuries.

Begging the Question
This fallacy, which is also called circular reasoning, is used when people use a claim itself as evidence for the validity of the claim. For example, a student would be begging the question if in response to the question, “Who was the most effective president of the United States,” she wrote, “Lincoln was the most effective president because he’s the best one we ever had.” Another student, asked to provide reasons for his choice of a favorite book would say, “This was the best book because I liked it.”

Evading the Issue
This type of reasoning is often used by public figures who do not want to discuss a particular topic for some reason. The reason may be valid, as in cases of confidentiality or security, or the topic may just be embarrassing or negative. For example, a mayor may respond to question about corruption in his administration by describing how the beautification of the city’s parks is progressing.

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