Logical reasoning PrepTest 126 · Section 1 · Question 17

Incorrect. This answer is the negation of the argument's assumption. The argument assumes that not knowing the name of something guarantees that you don't know what it is, not that knowing the name guarantees you know it.

Incorrect. The argument is about knowing what something is, not knowing it better, so this answer's comparative nature makes it out of scope.

Incorrect. This answer runs counter to the argument, where the name is treated as being key to understanding or having a concept of a thing.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Situation 1 - Someone finds a fruit tree and studies/harvests it without naming it
Situation 2 - Ancient societies didn't have an phrase for "moral rights"
Conclusion - It'd be absurd to say the person in situation 1 doesn't know about the fruit before naming it, so it's absurd to say the ancient societies didn't understand moral rights just because they didn't name them.

Answer Anticipation:
This argument falls into a common method of reasoning that is seen on the LSAT—the reductio ad absurdum, or the reduction to the absurd. In it, the ridiculousness of an argument is demonstrated by showing a parallel argument where the matching conclusion wouldn't be accepted.

For these arguments to be effective, two things need to be true. First, as with all arguments that feature comparisons, the relevant elements need to be comparable. Second, the situation that serves as the absurd conclusion has to reach an absurd conclusion.

In this question, the situations do seem similar, but any answer that establishes a relevant similarity or rules out a relevant difference could serve as a correct answer—any two situations will have some differences, and so this answer category is always in play. However, it isn't established that the fruit tree situation leads to an absurd conclusion in parallel—maybe that person doesn't know what the fruit is until it's named. This is another potential answer choice—the argument assumes that the situation it highlights to prove the incorrectness of an opposing point actually does so.

Answer Explanation:
This answer establishes that the situation used as a presumably absurd analogy does, in fact, lead to the conclusion the author wants to draw about the situation in the conclusion. If the fruit tree situation doesn't highlight a similar conclusion—if that person who kept harvesting and studying the tree didn't have some idea of what it was before naming it—then the opposing point wouldn't be absurd, as the author claims. Thus, this answer is necessary for the argument to work.

Key Takeaway:
An argument that uses an analogous situation to show the absurdity of a given conclusion is a common reasoning method on the LSAT. When it's used, the two situations have to be shown to be similar in all relevant ways, and the conclusion of the analogous situation has to be established as clearly wrong.

Incorrect. The argument treats naming something as necessary for knowing it. This answer establishes that the reverse relationship isn't true (knowing something isn't necessary for naming it), which isn't required for the original relationship to hold true.