LSAT Logical Reasoning Flaw Questions with the Same Argument

Logical Reasoning arguments often contain the same flaw as each other, but such arguments are often about very different topics.

It's somewhat infrequent for different arguments to contain both the same flaw and the very same topic.

In this blog post, I discuss the similarities between two such Logical Reasoning questions from The Next 10 Actual, Official LSAT PrepTests.

Both arguments are associated with Flaw question stems, meaning the question is asking us to identify the flaw, and both are on the topic of altruism and self-interest.

You'll need a copy of the book to follow along as I discuss the following two actual LSAT PrepTest questions:

1. PrepTest 29 (October 1999 LSAT), Section 4, Question 18 (page 41 in Next 10).

Question stem: "Which one of the following most accurately describes an error in the argument's reasoning?"

2. PrepTest 32 (October 2000 LSAT), Section 1, Question 19 (page 124 in Next 10).

Question stem: "A flaw in the argument is that it"

Both arguments reach the same conclusion:

Even behavior that might seem altruistic is actually self-interested.

We see this in the first sentence of the both questions, which contains the conclusion of each argument. The following sentences in each stimulus contain evidence for this.

The PrepTest 29 question suggests people engage in seemingly-altruistic behavior in the hopes of receiving some kind of reward or reciprocal benefit.

The PrepTest 32 question says people engage in seemingly-altruistic behavior in order to boost their self-esteem by feeling useful. Both arguments, on the face of it, seem rather reasonable.

However, the conclusions of both arguments are *too* certain given the way in which the evidence is presented.

The PrepTest 29 question says "can be described" in the 3rd-4th lines.

The PrepTest 32 question says "can be understood" in the 4th-5th lines.

Just because something "can be described" or "can be understood" in a particular way doesn't mean that it must be described or understood in that way. People can interpret actions and behaviors in multiple ways, not only in the ways suggested in these two arguments. The arguments are guilty of the same flaw - they both assume one possible interpretation to be the only possible interpretation, and they fail to consider that there could be other interpretations.