Checking for Common Fallacies

     
  • Ad hominem arguments attack someone's character rather than addressing the issues. (Ad hominem is Latin for "to the man.") It is an especially common fallacy in political discourse and elsewhere: "Jack Turner has no business talking about the way we run things in this city. He's lived here only five years and is just another flaky liberal." The length of time Turner has lived in the city has no bearing on the worth of his argument; neither does his political stance, which his opponent characterizes unfairly.

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  • Bandwagon appeals argue that because others think or do something, we should, too. For example, an advertisement for a rifle association suggests that "67 percent of voters support laws permitting concealed weapons. You should, too." It assumes that readers want to be part of the group and implies that an opinion that is popular must be correct.

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  • Begging the question is a circular argument. It assumes as a given what is trying to be proved, essentially supporting an assertion with the assertion itself. Consider this statement: "Affirmative action can never be fair or just because you cannot remedy one injustice by committing another." This statement begs the question because to prove that affirmative action is unjust, it assumes that it is an injustice.

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  • Either-or arguments, also called false dilemmas, are oversimplifications. Either-or arguments assert that there can be only two possible positions on a complex issue. For example, "Those who oppose our actions in this war are enemies of freedom" inaccurately assumes that if someone opposes the war in question, he or she opposes freedom. In fact, people might have many other reasons for opposing the war.

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  • False analogies compare things that resemble each other in some ways but not in the most important respects. For example: "Trees pollute the air just as much as cars and trucks do." Although it's true that plants emit hydrocarbons, and hydrocarbons are a component of smog, they also produce oxygen, whereas motor vehicles emit gases that combine with hydrocarbons to form smog. Vehicles pollute the air; trees provide the air that vehicles' emissions pollute.

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  • Faulty causality, also known as post hoc, ergo propter hoc (Latin for "after this, therefore because of this"), assumes that because one event followed another, the first event caused the second—for example, "Legalizing same-sex marriage in Sweden led to an increase in the number of children born to unwed mothers." The statement contains no evidence to show that the first event caused the second. The birth rate could have been affected by many factors, and same-sex marriage may not even be among them.

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  • Hasty generalizations are conclusions based on insufficient or inappropriately qualified evidence. This summary of a research study is a good example: "Twenty randomly chosen residents of Brooklyn, New York, were asked whether they found graffiti tags offensive; fourteen said yes, five said no, and one had no opinion. Therefore, 70 percent of Brooklyn residents find tagging offensive." In Brooklyn, a part of New York City with a population of over two million, twenty residents is far too small a group from which to draw meaningful conclusions. To be able to generalize, the researcher would have had to survey a much greater percentage of Brooklyn's population.

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  • Slippery slope arguments assert that one event will inevitably lead to another, often cataclysmic event without presenting evidence that such a chain of causes and effects will in fact take place. Here's an example: "If the state legislature passes this 2 percent tax increase, it won't be long before all the corporations in the state move to other states and leave thousands unemployed." According to this argument, if taxes are raised, the state's economy will be ruined—not a likely scenario, given the size of the proposed increase.

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