How to Spot Logical Fallacies in Argument Analysis GRE Questions - dummies

How to Spot Logical Fallacies in Argument Analysis GRE Questions

By Ron Woldoff, Joseph Kraynak

When you answer Argument Analysis questions on the GRE, the arguments may seem logical and fair on the surface but actually be fallacious (erroneous, flawed). Circular reasoning, erroneous cause-and-effect reasoning, and sweeping generalizations are three signs of weak arguments.

By spotting some of the more common logical fallacies, you can identify weaknesses in arguments and gather the knowledge required to determine which statements best support or refute an argument.

The GRE offers two Argument Analysis questions in each Verbal section. An Argument Analysis question consists of a short passage and a single question.

Identify circular reasoning

In circular reasoning, a premise supports a premise or a conclusion supports a conclusion. For example, a statement such as “The United States is the greatest country in the world, because no other country comes close” is an example of circular reasoning — trying to support the conclusion with another conclusion. Another example is “Most dentists prefer this toothpaste because four out of five dentists prefer it,” which is supporting a premise with a premise; in this case, the conclusion merely restates the premise.

You won’t see circular reasoning in the passage, but it may appear in the answer choices, especially when the question asks you to choose a statement that supports an argument. Watch out for answer choices that restate information already in the argument. These answers are wrong because restating an argument doesn’t make it true.

Spot erroneous cause-and-effect arguments

An erroneous cause-and-effect argument assumes that because one event followed another, the first event caused the second event. For example, suppose that you’ve been taking the same multivitamin every day for years. One day, you take a new multivitamin, and you are just full of energy. Your productivity at work triples, and you set a new record at the gym. Did this new multivitamin bring this energy? One might think so, but you don’t know for sure that the new vitamin caused the effect (your energy). Maybe something else caused it. If you also got plenty of rest, ate a great breakfast, and drank an extra coffee, maybe all that extra energy wasn’t from the new multivitamin.

Identify sweeping generalizations

A sweeping generalization applies a general rule to a specific case; someone may suppose that a plan that works in one context will certainly work in another. For example, someone may argue that because the addition of sharp-turn warning signs to roads in Town X reduced the rate of accidents, adding these signs to the roads in Town Y will surely have the same effect.

This argument uses a sweeping generalization by assuming that the roads in the two towns are similar. To weaken this argument, the correct answer choice may suggest that Town X has lots of curvy mountain roads, while Town Y has only straight, flat roads. Because sharp-turn warning signs don’t make straight roads safer, this new information weakens the argument.