Logical ReasoningDifficulty: Hard

PT107 S3 Q10 Explanation

The only motives that influence

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsFlaw

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Stimulus

The only motives that influence all human actions arise from self-interest. It is clear, therefore, that self-interest is on human action.

What this question is testing

Flaw

Your task

Describe the reasoning error the argument actually commits.

Common trap

Answers that name a real logical flaw the argument doesn't actually make.

Winning move

Articulate the gap in the reasoning yourself, then match it to the choice that describes that gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
10.

The reasoning in the argument is fallacious because

Answer choices

  1. Bad Conclusion Match3% picked this

    denies that an observation that a trait is common to all the events in a pattern can contribute to a

    This answer is saying that an observation was made that a certain trait is common to all the events in a pattern (the trait of self-interest is common to all the events in the pattern of human action), and then that the author denies that this can contribute to a causal explanation of human action. The conclusion almost does the opposite. The author certainly doesn't deny this observation, since it's her premise. And by calling this trait the chief influence it seems like she thinks that the observation can contribute to a causal explanation.

  2. Correct66% picked this

    takes the occurrence of one particular influence on a pattern or class of events as showing that its influence outweighs any

    Why this is right

    Any time an answer is structured "Takes X as showing that Y", we would want X to match the Evidence and Y to match the Conclusion. Did the evidence talk about the occurrence of one particular influence on a pattern/class of events? Sure. She said that "self-interest" is particular influence on the class of "human actions" that "occurs in every case". Did the conclusion say that the influence of "self interest" outweighs any other influence? Yes. She said that it is the chief influence on human action. The "chief" outranks everyone else in the tribe. The chief influence is the #1 influence. Since the answer matches, we know it's right.

    Skill tested: Flaw · how this choice captures the argument's function is the move to repeat next time.

  3. Wrong Flaw4% picked this

    concludes that a characteristic of a pattern or class of events at one time is characteristic of similar patterns or classes

    This answer choice describes a Temporal Flaw or Sampling flaw, in which the author assumes that "if it was true before / true here, then it will be true again / true everywhere." Any answer structured like "concludes that [thing thing] is [that thing]", we would want the former to match the Evidence and the latter to match the Conclusion. This answer is saying the author concludes that "something that was true at one time will therefore be true at all times. That doesn't reflect any move the author made here. This answer would be describing an argument that sounded more like, "Self-interest was the chief influence on human action during WWII. Thus, self-interest must always be the chief influence on human action."

  4. Reversed Parts23% picked this

    concludes that, because an influence is the paramount influence on a particular pattern or class of events, that influence is the only influence on

    Any time an answer is structured concludes that, because of X, Y we would want X to match the Evidence and Y to match the Conclusion. Was the Evidence saying an influence is the paramount (chief) influence on a class of events? No, the conclusion said that. We could eliminate this answer at this point. For what it's worth, the other idea in this answer choice is that "self-interest is the only influence on human action", which was not an idea that appeared at all in the argument. We were told that self-interest is the only influence that is involved in 100% of human actions, but not that it is the only influence on human action.

  5. Wrong Flaw4% picked this

    undermines its own premise that a particular attribute is present in all instances of a certain pattern

    The wording "undermines its own premise" describes the famous Internal Contradiction flaw (which is almost never a correct answer). The author's conclusion does not undermine the premise in any way.

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