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#26330
Complete Question Explanation

Parallel Flaw—SN. The correct answer choice is (C)

The premises in the stimulus provide two conditional rules: first one states that if there are frequent mutations in a species, there must be new evolutionary adaptations in each generation, whereas the second one suggests that if a species survives dramatic environmental changes, there must be new evolutionary adaptations in each generation. Both premises contain the same necessary condition, while their sufficient conditions differ. The conclusion attempts to connect these conditions into a third conditional rule. However, there is no valid connection between them, which is why the conclusion is invalid.

The erroneous pattern of reasoning can be diagrammed as follows:
  • Premise: Frequent mutations ..... :arrow: ..... New evolutionary adaptations in each generation

    Premise: Species survive changes ..... :arrow: ..... New evolutionary adaptations in each generation

    Conclusion: Frequent mutations ..... :arrow: ..... Species survive changes
The correct answer should contain two conditional statements in the premises sharing the same necessary condition. This is a unique construction for a conditional argument, and so the Premise Test is the most effective approach to eliminating answer choices. Any answer choice that does not contain two conditional premises with identical necessary conditions should be immediately eliminated.

Answer Choice (A): This answer choice does not match the flawed reasoning in the stimulus. First of all, the two conditional rules in the premises do not have identical necessary conditions. Also, the flaw in this answer choice is a different kind of error than the error in the stimulus. One of the premises concerns “walls,” while the other premise deals with “stone walls.” It is invalid to make a conclusion about one based on evidence concerning the other.

Answer Choice (B): There is only one conditional rule in the premises, so this answer choice does not match the Premise Test. Also, this answer choice is valid so it fails the Validity Test. The second sentence is a restatement of the conditional rule in the first sentence. While the language is different, the logic of the original premise did not change. The logic can be diagrammed as follows:
  • Premise: Different Audience ..... :arrow: ..... Different Reaction

    Premise: Different Audience

    Conclusion: Different Reaction


Answer Choice (C): This is the correct answer choice. According to the first premise, a perfectly honest person must always tell the truth. The second premise suggests that a morally upright person must always tell the truth as well. Both of these premises share the same necessary condition. The conclusion attempts to connect the two sufficient conditions in an invalid conditional relationship. This matches the stimulus. The logic of this answer choice can be diagrammed as follows:
  • Premise: Perfectly Honest ..... :arrow: ..... Tell The Truth

    Premise: Morally Upright ..... :arrow: ..... Tell The Truth

    Conclusion: Perfectly Honest ..... :arrow: ..... Morally Upright
Answer Choice (D): This answer choice is actually valid and so it fails the Validity Test. The answer choice properly connects two conditional rules into a valid chain relationship. The logic can be diagrammed as follows:
  • Premise: Productive Herb Garden ..... :arrow: ..... Soil Well Drained

    Premise: Soil Well Drained ..... :arrow: ..... Good Soil

    Conclusion: Productive Herb Garden ..... :arrow: ..... Good Soil
Answer Choice (E): Unlike the stimulus, the premises in this answer choice can be connected to form a valid conditional chain. However, the answer choice is flawed because it switches from “healthful diet” in the premises to “being healthy” in the conclusion. The logic can be diagrammed as follows:
  • Premise: Healthful Diet ..... :arrow: ..... Well Balanced Diet

    Premise: Well Balanced Diet ..... :arrow: ..... Fruits and Vegetables

    Conclusion: Being Healthy ..... :arrow: ..... Fruits and Vegetables
 al_godnessmary
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#25145
I just want to check how the diagramming works to see if I made any mistakes. Thanks!

This is what I got for the stem:

Flaw: Mistaken Reversal for second condition

Mutations Freq Occur :arrow: Each Generation Adapt

Survive :arrow: Each Generation Adapt

Mutations Freq Occur :arrow: Survive (INCORRECT INFERENCE BECAUSE NOTHING LINKS THESE TWO)


And then for answer C...

Honest :arrow: Every Sit Truth
Morally Upright :arrow: Every Sit Truth
Honest :arrow: Morally Upright


And therefore it matches the flawed reasoning because it starts with two different things leading to the same thing, and concludes that the two different things therefore cause each other?
 Robert Carroll
PowerScore Staff
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#25202
al,

Everything looks perfect in the diagramming and in your reasoning. Way to go!

Robert Carroll

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