PrepTest 157

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

Question prompt

Committee chairperson: No new Remaining source text redacted.
Why the credited answer is right

Credited answer: C

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

Argument or Facts

Facts

Strategy Overview

Argument or facts in passage? If argument, identify premises and conclusions Sufficient/necessary conditions in the passage? If so, diagram statements and draw any deductions Use anticipation to find the answer choice that is absolutely 100% true

Answer Anticipation

This set of facts features a few "if-then" keywords, including a "then-denying" keyword ("no"), an "if-denying" keyword ("unless"), and a few "if" keywords ("all," twice). These send us a clear signal that we should diagram these statements to help us draw a conclusion that must be true.
The first sentence is challenging to diagram since it uses "if-" and "then-denying" keywords. When we have a combination of an "if-denying" keyword and another keyword, the easiest way to diagram is to replace the "if-denying" keyword with "if not." Because an "or" follows the "if not," we'll need to make sure to apply the "not" to both conditions and the "or," changing it to "and." So, we can translate the first sentence to: "If this committee has not received the proposal and Dean Wilson has not received the proposal, then the new course will not be approved for next year's schedule." We can diagram that and take its flipside: P: NOT committee received and NOT Dean Wilson received → NOT course approved / Course approved → Committee received or Dean Wilson received
The next sentence provides two premises. First, it establishes Dean Wilson received just one proposal. This doesn't really connect to the "if-then" statement we diagrammed, so let's skip over this information for now. Second, it establishes that "all" the new proposals the committee received are for upper-level courses. We can diagram that as an "if-then" statement, as "all" is an "if" keyword. Let's diagram, take its flipside, and add it to our list of premises: P: NOT committee received and NOT Dean Wilson received → NOT course approved / Course approved → Committee received or Dean Wilson received P: Committee received → Upper-level / NOT upper-level → NOT committee received
The last sentence provides one more "if-then" statement that uses the keyword "all." Once more, let's diagram, take its flipside, and add it to our list of premises: P: NOT committee received and NOT Dean Wilson received → NOT course approved / Course approved → Committee received or Dean Wilson received P: Committee received → Upper-level / NOT upper-level → NOT committee received P: Upper-level → Prerequisite / NOT prerequisite → NOT upper-level
Notice that the second and third premises share the condition "Upper-level." Since "Upper-level" appears as the "then" condition of the second premise and the "if" condition of the third premise, we can connect those premises. So, we can conclude: P: NOT committee received and NOT Dean Wilson received → NOT course approved / Course approved → Committee received or Dean Wilson received P: Committee received → Upper-level / NOT upper-level → NOT committee received P: Upper-level → Prerequisite / NOT prerequisite → NOT upper-level

Answer choices

  1. A
    If there are no Remaining source text redacted.
    Why choice A is not credited

    If we diagrammed this claim, it would be "NOT upper-level → NOT prerequisite." This is an inaccurate version of the third premise. We know that if there are upper-level courses, then they will have prerequisites. However, that doesn't mean that upper-level courses are the only courses with prerequisites. Some lower-level courses could have prerequisites, too. The type of deduction this answer choice makes is often called an "inverse" flaw or an "illegal negation," and such deductions will always be wrong on Must Be True questions.

  2. B
    If all of the Remaining source text redacted.
    Why choice B is not credited

    If we diagrammed this claim, it would be "All upper-level approved → Committee approved all courses." This is an inaccurate version of the second premise. It looks a bit like the "converse" flaw or "illegal reversal" of that premise. This answer choice also misconstrues the second premise's conditions since this answer choice is about approving all the courses rather than just approving one course.

    And, if we compare this statement to the rest of the premises, we'll see that it's not necessarily true. The committee would not have to approve all the proposals for all the new courses to be upper-level. The committee could have rejected a few upper-level proposals it received, and Dean Wilson could have rejected all the proposals they received, and all the new courses would still be upper-level courses. For these reasons, we can eliminate (B).

  3. C
    If there is more Remaining source text redacted.
    Why choice C matches the stem

    This statement must be true. This statement is consistent with the following conclusion we drew:

    Conclusion: Course approved → Prerequisite or Dean Wilson received

    If there is more than one new course next year, then at least one of them will have a prerequisite. We know that Dean Wilson only received "one new course proposal." Even if that is a lower-level course without a prerequisite and Dean Wilson approves it, that would only represent one new course. If there's at least one other new course, its proposal would have been reviewed by the committee. The committee only reviewed upper-level courses with prerequisites, so that course would necessarily have a prerequisite. Since (C) is a demonstrably true statement based on these premises, we can select it and advance directly to the next question.

  4. D
    If the new course Remaining source text redacted.
    Why choice D is not credited

    This is a very tempting answer choice! If it said that, "If the new course proposal that Dean Wilson received is for an upper-level course, then all new courses offered next year will have prerequisites," it would be accurate. That would mean that all the courses the committee and Dean Wilson reviewed and approved were upper-level, all with prerequisites.

    However, (D) doesn't quite say that. It says, "If the new course proposal that Dean Wilson received is for an upper-level course, then all courses offered next year will have prerequisites." It doesn't specify that all *new* courses will have prerequisites. It describes all courses generally. And we don't know anything about preexisting courses. Many of them could be lower-level courses lacking prerequisites, making this answer a potentially false statement. What a difference one word makes!

  5. E
    If there are no Remaining source text redacted.
    Why choice E is not credited

    This isn't necessarily true. If there are no new upper-level courses next year, that would mean that the committee rejected all of the proposals it received. But that doesn't mean that Dean Wilson would have had to accept the proposal they received. The Dean could have rejected that proposal, too. There's no stipulation that there has to be at least one new course this year.

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