PrepTest 157

[lcid:3725] Prep Test 157 LSAT — Logical Reasoning — S2 Logical reasoning

Question prompt

Because of the ubiquity Remaining source text redacted.
Why the credited answer is right

Credited answer: B

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

Argument or Facts

Argument

Valid or Flawed

Flawed

Strategy Overview

Argument or facts? Always argument, so identify premises and conclusions of argument Anticipate why the premises are not enough to show that the conclusion is true

Answer Anticipation

On Strengthen with a Sufficient Premise questions, we need to find the answer choice that makes the conclusion valid if added as another premise. After completing many of these questions, observant LSATers start to see a pattern. For most Strengthen with a Sufficient Premise questions, the author will introduce a "new," important idea in the argument's conclusion. The premises will not discuss this "new," important idea. In introducing this new idea, the author creates a gap between the premises and the conclusion. The correct answer will address the gap between the premises and the new idea, often simply linking the two concepts with a strong "if-then" statement. In this conclusion, "develop a lifelong interest in literature" is the new idea. The premises discuss reading stories but not developing an interest in literature. To make this argument valid, we need a premise that establishes that few children will develop such an interest. The correct answer will probably connect the new idea to the premise that few children spend their free time reading stories. We can anticipate that the correct answer will link these ideas together. We can think of this anticipation as a translated "if-then" statement ("If you do not read stories as a child, then you will not develop a lifelong interest in literature") or as a diagram ("NOT read stories → NOT develop a lifelong interest in literature") — whichever is easier for you! Let's look for either in the answer choices.

Answer choices

  1. A
    No children who spend Remaining source text redacted.
    Why choice A is not credited

    Diagramming this answer choice is a little complicated. But once we do, we'll see that it doesn't match our anticipation. To diagram this, we'll need to use the "No," a "then-denying" keyword. We can put either condition on either side of the arrow, so long as we add a "NOT" to the "then" side. That would give us this "if-then" statement and flipside:

    Read stories → NOT fail to develop a lifelong interest in literature / Fail to develop a lifelong interest in literature → NOT read stories


    If we use a "positive mindset" on the "NOT fail" double negative, we can translate that to simply "develop a lifelong interest in literature":

    Read stories → Develop a lifelong interest in literature / NOT Develop a lifelong interest in literature → NOT read stories


    As we can see, this doesn't resemble the "NOT read stories → NOT develop a lifelong interest in literature." Rather than connect the premise to the new idea in the conclusion, it says that if we don't have the premise, then we won't have the new idea in the conclusion. In other words, the correct answer to a Strengthen with a Sufficient Premise question should resemble "Premise → Conclusion." It shouldn't resemble "NOT Premise → NOT Conclusion." For this reason, (A) is incorrect.

  2. B
    Only those people who Remaining source text redacted.
    Why choice B matches the stem

    This answer choice matches our anticipation! However, diagramming it is definitely challenging. We'll need to notice that the "only" is a "then" keyword. That will give us this "if-then" statement and flipside:


    Develop a lifelong interest in literature → Read stories / NOT read stories → NOT develop a lifelong interest in literature


    The flipside matches our anticipation, so we can confidently select (B) and move directly to the following question.

    After all, if we add this premise to the argument, it becomes valid. Suppose that (B) is true — suppose that we know that if you don't spend your free time reading, then you won't develop a lifelong interest in literature. In that case, most children who spend their time watching TV rather than reading will not develop a lifelong interest in literature. So, this answer choice makes the argument valid. We can select it and advance to the following question.

  3. C
    No children who grow Remaining source text redacted.
    Why choice C is not credited

    We can eliminate this answer choice immediately because it lacks the new term in the conclusion. It doesn't discuss whether any kids "develop a lifelong interest in literature." Therefore, this can't make the conclusion valid. You can't have a valid conclusion with a term that doesn't appear in any of the premises, so adding this premise won't make the conclusion follow logically.

  4. D
    Few people who watch Remaining source text redacted.
    Why choice D is not credited

    This doesn't match our anticipation. It doesn't connect the author's premise to their conclusion, whether we thought of that connection as a translated "if-then" statement ("If you do not read stories as a child, then you will not develop a lifelong interest in literature") or as a diagram ("NOT read stories → NOT develop a lifelong interest in literature"). Instead, it just establishes that people who watch a "great deal of television" will usually not develop a lifelong interest in literature. However, the author's premises don't say that most children watch a great deal of television. The premises just say that televisions are common and that few children "spend their free time reading stories." These children may spend their free time watching television instead of stories, but that doesn't mean they're necessarily watching "a great deal of television." In other words, since the author doesn't include a premise that establishes that most children watch a great deal of television, this answer choice does not connect the author's premise to their conclusion.

  5. E
    Few children who spend Remaining source text redacted.
    Why choice E is not credited

    Like (C), we can immediately cross this answer choice off once we see that it lacks the new term in the conclusion. It doesn't discuss whether kids "develop a lifelong interest in literature." Therefore, this can't make the conclusion valid. A conclusion that features an idea that isn't discussed in any of the premises will never be valid, so adding this premise won't make the conclusion follow logically.

Discussion

View all discussions Start a discussion