Logical ReasoningDifficulty: Hard

PT101 S2 Q21 Explanation

Newspaper editor: Law enforcement

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

TopicsSufficient Assumption

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Stimulus

Newspaper editor: Law enforcement experts, as well as most citizens, have finally come to recognize that legal prohibitions against gambling all share a common flaw: no matter how diligent the effort, the laws are impossible to enforce. Ethical qualms notwithstanding, when a law fails to be effective, why there should be no legal prohibition against gambling.

What this question is testing

Sufficient Assumption

Your task

Find the assumption that, if added, guarantees the conclusion follows.

Common trap

Answers that only partly bridge the gap, leaving the conclusion unproven.

Winning move

Identify the new term in the conclusion and pick the choice that links it to the evidence.

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

The question
21.

Which one of the following, if assumed, allows the argument’s conclusion to

Answer choices

  1. Correct60% picked this

    No effective law is

    Why this is right

    This says effective ? enforceable not enforceable ? not effective which was our prediction (in contrapositive form). We know gambling laws are impossible to enforce. According to this answer that means that gambling laws are not effective. And according to the second to last sentence, a law that is ineffective should not be a law. Thus, we've proven that gambling laws shouldn't be laws (i.e. there should be no legal prohibition against gambling).

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

  2. Opposite / Reversed15% picked this

    All enforceable laws are

    We were looking for impossible to enforce ? not effective This answer says possible to enforce ? effective We are always on guard for this type of "Right ideas, Wrong order" trap answer on Assumption questions.

  3. Repeats Something We Know22% picked this

    No legal prohibitions against gambling are

    This is incredibly rare. You almost never see answer choices repeat a fact, but we were explicitly told "legal prohibitions against gambling all share a common flaw: the laws are impossible to enforce". So this answer adds nothing new to our argument.

  4. Out of Scope2% picked this

    Most citizens must agree with a law for the law to

    Out of Scope: must agree with law Sufficient Assumption correct answers almost never bring in any new ideas, so this new concept of "51% of citizens must agree in order for law to be effective" is a big turnoff. We need to establish that gambling laws are ineffective in order to prove they shouldn't be laws. This rule does have the power to prove something is ineffective, but we would have to establish that "most citizens do not agree with gambling laws" to trigger this. Were we told that "most citizens do not agree with gambling laws"? No, we were only told that most citizens have come to recognize that gambling laws share a common flaw of being unenforceable. Sufficient Assumption doesn't tolerate any gaps, so this answer would not let us fully derive the conclusion.

  5. Out of Scope1% picked this

    Most citizens must agree with a law for the law to

    Out of Scope: must agree with law Sufficient Assumption correct answers almost never bring in any new ideas, so this new concept of "51% of citizens must agree in order for law to be effective" is a big turnoff. We need to establish that gambling laws are ineffective in order to prove they shouldn't be laws. This rule has no power to prove that a law is ineffective, so it's worthless to us.

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