How to Answer Pattern-of-Reasoning Questions on the LSAT

The LSAT exists partly to test your ability to understand how arguments work. A well-structured argument is a beautiful thing. A reader can follow the steps of the reasoning from start to finish with no effort at all, and the conclusion should seem self-evident if the author has done her job right.

How to identify pattern-of-reasoning questions

These logical reasoning questions ask you to choose an answer that uses the same method of reasoning as the argument or, less often, directly ask you what type of reasoning the author uses to make an argument. Look over these examples of pattern-of-reasoning questions:

  • Which one of the following exhibits a pattern of reasoning most similar to that exhibited by the argument above?

  • Which one of the following arguments is most similar in its pattern of reasoning to the argument above?

  • The reasoning in which one of the following arguments is most similar to that in the argument above?

  • Which one of the following most closely parallels the newscaster’s argument in its reasoning?

  • Which one of the following is most closely parallel in its flawed reasoning to the flawed reasoning in the argument above?

  • Which one of the following employs a flawed argumentative strategy that is most closely parallel to the flawed argumentative strategy in the letter above?

  • Which one of the following uses flawed reasoning most similar to that used in the argument above?

  • The flawed reasoning in the argument above is most similar to that in which one of the following?

For the purposes of the LSAT, the chief methods of reasoning are as follows:

  • Deductive, which is reaching a specific conclusion from general premises.

  • Inductive, which is drawing a general conclusion from specific premises and which includes the following methods:

    • Cause and effect, which shows that one event resulted from another.

    • Analogy, which shows that one thing is sufficiently similar to another thing such that what holds true for one is true for the other.

    • Statistics, which uses population samples (surveys) to reach conclusions about the population as a whole.

When you know you’re dealing with a pattern-of-reasoning question, you just need to focus on the way the author makes the argument to make sure you choose an answer that follows the logic most exactly.

Don’t choose an answer just because it deals with the same subject matter as the given argument. These choices are often traps to lure you away from the answer that more exactly duplicates the author’s logic but addresses another topic.

It doesn’t matter whether the argument makes sense. If the given argument isn’t logical, pick an answer choice that isn’t logical in the same way.

You may focus on the method of reasoning better if you substitute letters for ideas in the argument.

A pattern-of-reasoning example

Here’s an example of a pattern-of-reasoning question:

Formaldehyde is a known carcinogen. Many nail polishes contain formaldehyde. Therefore, anyone who wears nail polish will get cancer.

Which one of the following is most closely parallel in its flawed reasoning to the flawed reasoning in this argument?

  • (A)Hot dogs can contain insect parts. Insects are dirty and carry disease. Therefore, people should not eat hot dogs.

  • (B)Ultraviolet rays can cause skin cancer. Sunscreen can prevent damage from ultraviolet rays. Therefore, people who wear sunscreen will not get cancer.

  • (C)Sodium can cause high blood pressure. Potato chips contain sodium. Therefore, anyone who eats potato chips will get high blood pressure.

  • (D)Beans contain a large amount of dietary fiber. Dietary fiber may be able to prevent some kinds of cancer. Therefore, people who do not eat beans will get cancer.

  • (E)Alcohol consumed during pregnancy can cause fetal brain damage. Wine contains alcohol. Therefore, pregnant women should not drink wine.

Read the question. You need to find the answer that uses the same process of reasoning as the argument. You know that this process of reasoning is flawed because the question tells you so. So, how is it flawed? The flaw is in the conclusion, which makes an unjustified assumption that the presence of a known carcinogen in nail polish means that everyone who wears nail polish will get cancer.

The problem with the conclusion is that it assumes that a carcinogen automatically causes cancer in everyone who encounters it, which isn’t justified by the evidence presented in the argument. The argument doesn’t say that formaldehyde always causes cancer or that nail polish causes cancer; all it says is that formaldehyde can cause cancer and that nail polishes contain formaldehyde.

The flaw isn’t the important thing here. The reasoning process is all you really care about. You want to find the answer choice that uses the same process of reasoning as the argument. For the purposes of finding the answer with parallel reasoning, break down the argument’s structure. You can rewrite it in a formula, like this: F can cause C; NP contains F; therefore, NP always causes C.

Which answer choice makes this same kind of logical leap?

  • Choice (A) says that H can contain I; I causes disease; therefore, don’t eat H. That’s not the same as the argument.

  • Choice (B) says that U can cause C; S prevents damage by U; therefore, S prevents C. That’s not the same as the argument.

  • Choice (C) says that S can cause H; P contains S; therefore, P always causes H. That looks identical to the argument’s reasoning.

  • Choice (D) says that B contains F; F can prevent C; therefore, B prevents C. That’s not the same as the argument.

  • Choice (E) says that A during P causes BD; W contains A; therefore, P shouldn’t drink W. That’s not the same as the argument.

Choice (C) is the correct answer because it exactly parallels the argument’s reasoning.

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