LSAT 117 | Section 4 | Logical Reasoning: Q19

LR Question 19 Explanation

QUESTION TEXT: Political scientist: All governments worthy of respect …

QUESTION TYPE: Flawed Parallel Reasoning

CONCLUSION: Any government that protects minorities allows dissent.

REASONING: All governments worthy of respect allow dissent. No government worthy of respect leaves minorities unprotected.

ANALYSIS: Let’s simplify the structure.

Worthy governments → permit dissent
Worthy governments → protect minorities
Therefore: protect minorities → permit dissent

In symbols:

A → B
A → C
Therefore: C → B

The author treats two characteristics that share the same sufficient condition as if one implies the other.

An analogy might help to see the flaw here.

• All dogs are mammals.
• All dogs have tails.
• So, everything with a tail is a mammal.

That’s obviously not true. Reptiles have tails and they’re not mammals. Just because two traits are both associated with dogs does not mean one trait implies the other.

Likewise, even if all respectable governments both protect minorities and permit dissent, a government could protect minorities without being one of those respectable governments.

The answer choice should follow the same structure. A certain thing has two characteristics, and then the conclusion thinks those two characteristics must be related.

___________

1. This switches meanings. At first, “those they serve” means a politician’s constituents. Then it treats serving the nation as a whole as if it were the same thing as serving one’s constituents. That’s not the same flaw as the stimulus.
2. CORRECT. This has the same structure: Jazz musician → can improvise. Jazz musician → can read music. Therefore: can read music → can improvise. Two conditional statements share the same sufficient condition, and the argument improperly infers that one necessary condition implies the other.
3. This also uses conditional statements, which might have made it tempting. But the flaw is different. This makes a negation mistake. Cool, dry → large mammals → not abundant plants. From this, it concludes: Not cool, dry → abundant plants. That doesn’t follow.
4. This uses “some”, while the stimulus uses two universal conditionals (“all”).
5. This argument relies on a false dilemma: if a book reveals everyone’s motives, it assumes it must be written in the third person. The stimulus never relies on a false dichotomy.