PrepTest 103

[lcid:3508] Prep Test 103 LSAT — Logical Reasoning — S1 Logical reasoning

Question prompt

Some people think that Remaining source text redacted.
Why the credited answer is right

Credited answer: E

The notes below walk through why it fits the stem and how to eliminate the rest.

Argument or Facts

Argument

Valid or Flawed

Valid

Question Type

Cannot Be True Questions

Stimulus Summary

Some people: Some politicians are rotten Author: Deceit is a part of being rotten → All effective politicians are rotten Effective politician → Deceitful Scrupulously honest → ~Effective politician

Answer Anticipation

Cannot be True questions are all about contradictions - we need an answer that explicitly contradicts something from the stimulus. And when the stimulus involves conditional logic, there’s a common type of correct answer. But before we get to that, let’s break down the stimulus! First, the argument starts with what “[s]ome people” believe - an opposing point that likely won’t factor into the correct answer. After all, the only thing that would contradict this statement is that no one believes there are some rotten politicians in every group. From there, it moves into the Author’s conclusion - though we don’t care about it as a conclusion, since we’re told to treat all her statements as true. Here, then, we can diagram it out, as we did in the Summary, using “if” as the sufficient indicator. After that, we get another conditional, with “must” introducing a necessary condition. And then, finally, we get another conditional (“Someone” being used as “Everyone” here to introduce a sufficient condition). Looking at these statements, they don’t chain together, so we don’t have to do any work there. Instead, we should expect a common answer type in Cannot be True questions that have conditional statements - something that establishes the presence of a sufficient condition without its necessary condition. Let’s take a look.

Answer choices

  1. A
    Some people think all Remaining source text redacted.
    Why choice A is not credited
    We learn that some people think that in any group (“barrel”) of politicians, some are rotten. However, there are plenty of other people in the world other than those “[s]ome,” and some of those may believe that all politicians are rotten.
  2. B
    Some politicians are scrupulously Remaining source text redacted.
    Why choice B is not credited
    The Author argues that effective politicians must be deceitful, but that doesn’t preclude some ineffective politicians from being scrupulously honest.
  3. C
    Some people define a Remaining source text redacted.
    Why choice C is not credited
    We get the Author’s definition of a politician’s job, but other people could define that job in any other way - including obeying the rules of society.
  4. D
    Some deceitful politicians are Remaining source text redacted.
    Why choice D is not credited
    The Author argues that all effective politicians are deceitful (Effective → Deceitful). That leaves open the possibility that some deceitful politicians are ineffective, since being deceitful isn’t sufficient to prove effectiveness.
  5. E
    Some scrupulously honest politicians Remaining source text redacted.
    Why choice E matches the stem
    The Author establishes deceit as necessary (“must be”) to doing a politician’s job effectively (“properly”). As such, every effective politician is deceitful, and thus none of them can be scrupulously honest. This answer is contradicted by the stimulus, so this is the correct answer.

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