In the first paragraph, the author refers to a highly reputed critic's persistence in believing van Meegeren's forger...

Christopher on October 19, 2019

Diagram of Parallel Reasoning

All the examples of parallel reasoning was easily to diagram with sufficient and necessary or quantifier techniques. Typically, are these question type able to be diagrammed? Has an example ever existed where a stimulus couldn't be diagrammed? If so, could you please provide an example?

3 Replies

Irina on October 19, 2019


Absolutely. Parallel reasoning questions that involve an argument consisting of conditional statements are only a subset of these types of questions. Parallel reasoning questions that involve no conditional relationships are usually not diagrammed.

Some examples:

-Nov 2018 LSAT S4 Q5

Businessperson: Brenner and Chen are the only applicants who have the qualifications we require. But Brenner has a history of not getting along with coworkers, so we should hire Chen.
Which one of the following arguments is most similar in its reasoning to the businessperson's argument?

-Nov 2018 LSAT S4 Q15

Commentator: The reported epidemic of childhood obesity in our country is a myth. Over the last 8 years, there was only a 1 pound (45 kilogram) increase in children's average weight. This is not a substantial increase, so the proportion of children who are obese cannot have increased substantially.
Which one of the following contains flawed reasoning most similar to the flawed reasoning contained in the argument above?

-Sep 2018 LSAT S2 Q 23

A gram of the artificial sweetener aspartame is much sweeter than a gram of sugar. Soft drinks that are sweetened with sugar are, of course, sweet, so those sweetened with aspartame must be even sweeter. Thus people who regularly drink soft drinks sweetened with aspartame will develop a preference for extremely sweet products.
Which one of the following arguments exhibits flawed reasoning that is most similar to flawed reasoning in the argument above?

-Sep 2018 LSAT S3 Q11

Lobbyist: Those who claim that automobile exhaust emissions are a risk to public health are mistaken. During the last century, as automobile exhaust emissions increased, every relevant indicator of public health improved dramatically rather than deteriorated.
The flaw in the lobbyist's reasoning can most effectively be demonstrated by noting that, by parallel reasoning, we could conclude that

Christopher on October 20, 2019

What are some ways to correctly complete questions without conditional relationships?

Skylar on October 20, 2019


Your approach to parallel reasoning questions without conditional language should be primarily the same as your approach to those with conditional language. First, you want to break down what the given passage is saying (in this case, break down does not mean to diagram, but instead to understand the role of each statement and how the logic proceeds). Then, you should read through the answer choices and select the one that best matches the pattern you identified in the given passage.

For example, if we were to approach the first example Irina gave (Nov 2018 LSAT S4 Q5) about Brenner and Chen, we would first break down the passage to discover a pattern of logic as follows:

We are given two exclusive choices (Brenner and Chen)
A flaw in one choice is recognized. (Brenner)
Therefore, we conclude that the other choice is best. (Chen)

As we proceed to the answer choices, we should look for this same/a closely similar pattern.

Does this make sense? Please let us know if you have any other questions!