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Humanities LibreTexts

3: Informal Fallacies - Mistakes in Reasoning

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  • What is a fallacy? Simply put, a fallacy is an error in reasoning. It employs a method of reasoning to reach a conclusion that is usually incorrect, but the flaw isn’t in the claims or conclusions, but rather in the connections between them (although the method of reasoning can sometimes go right in informal fallacies, formal fallacies are always wrong and those will be covered later). A fallacy can arise for two reasons:

    1. When we mistakenly assume that we have proven our conclusion when we have not
    2. When we assume we have stronger evidence for the conclusion than we really do

    Hence, when you commit a fallacy it typically means that you lack in some way the proper evidence necessary to support your conclusion. A fallacy does not mean that the conclusion is necessary false, just that the premises provided are not strong enough to show that the conclusion is in fact true. There are also fallacies that have faulty inferences at their base, resulting in inappropriate logical steps leading to the claimed conclusion. Why should we study fallacies? First, and most importantly, so that you don’t commit them. You want your reasoning to be proper, and the surest way to meet these goals is to avoid fallacies at all costs. Second, learning about fallacies is a great way to correct biases in your own reasoning that are maybe too deep to spot on your own. You’d be amazed how much bad reasoning you learn from parents, family, and friends, your culture, or the city you’ve been raised in. This brings me to the third point, you want to learn fallacies so you can see the errors in reasoning others commit: Politicians, lawyers, newspaper reporters, bloggers, Wikipedia, etc. are just some of the list. Many times, fallacies don’t just happen on accident; they are often committed with some kind of intent or reaction in mind. Spotting them enables you to make clear and educated choices about who and what to believe, to prevent falling prey to schemes or false opinions, and will enable you to communicate more effectively with others.