Logical Reasoning

PT127 · S2 · Q15 If Agnes's research proposal

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If Agnes's research proposal is approved, the fourth­ floor lab must be cleaned out for her use.

Conclusion

The 4th floor lab must be cleaned out.

If Agnes's proposal is approved, the 4th floor lab must be cleaned out. Only the proposals the director supports will be approved, and the director will support Agnes's proposal.

Evaluation

This might seem pretty valid at first, but whenever we're doing Flaw and we see conditional language, we should examine the directionality to make sure the author is thinking through it properly. The conditional trigger word here is "only", which always indicates the Necessary condition (right-side of the arrow).

Approved → Director Supports

The author is reasoning,

His reasoning looks like "Director Supports → Approved", so he is doing an Illegal Reversal of the conditional logic.

Goal

When authors mess up conditional logic, the fancy name for it is confusing Necessary with Sufficient (or vice versa). The informal way to object to it is to say,

15.

The argument's reasoning is flawed because the argument

  1. presumes, without providing justification, that

    Out of Scope Comparison: "bigger"

    Immanuel's proposal has nothing to do with the main conclusion. So any comparison between the 4th floor and 2nd floor is out of scope when it comes to how the author is attempting to arrive at her conclusion. But this answer may seem like an assumption involved in drawing the subsidiary conclusion in the 3rd sentence. However, it's possible that the 4th floor and 2nd floor labs are the same size, but more than one research project can take place in a given lab. Thus, since Agnes needs more space then Immanuel, she might need all of the 4th floor cleaned out for her use, while Immanuel can just keep working in the 2nd floor lab, along with other researchers using the remainder of the 2nd floor lab's available space.

    6% picked this

  2. Correct

    fails to consider the possibility

    Why this is right

    Would it weaken the author's argument if a proposal can be rejected even with the director's support? Yes! The author is thinking that since the director supports Agnes's proposal, that proposal will get approved. This answer doesn't use the Necessary vs. Sufficient wording it could have used; instead, it demonstrates why the author's Illegal Negation was an illegitimate inference. The argument establishes that there would never be a case of Approval but No Support. But there could still be cases where there is Support but No Approval.

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

    75% picked this

  3. presumes, without providing justification, that

    Trap

    Too Strong / Out of Scope Comparison: "equal enthusiasm" Nothing in the argument hinges on the relative degree of support, so it's irrelevant whether the director supports one proposal more than the other or equally.

    4% picked this

  4. fails to consider the possibility

    Out of Scope

    Out of Scope: "once proposal is approved" Immanuel's proposal has nothing to do with the reasoning the author is using to get to her conclusion. Would it hurt the author's argument if Immanuel wanted a bigger lab once his proposal was approved? Nope. If Immanuel's and Agnes's proposals are both approved, the 4th floor lab gets cleaned out, and the author wins her conclusion. Immanuel's desire for a bigger lab is irrelevant to the conclusion, unless we add a completely superfluous idea that "If Immanuel wants a bigger lab, then the 4th floor lab won't get cleaned out".

    5% picked this

  5. presumes, without providing justification, that

    Too Strong: "no other lab"

    The author has simply stated that if Agnes's proposal is approved, they'll give her the 4th floor lab. That doesn't force the author to believe that the 4th floor lab is the only adequate possibility for Agnes. It might be one of several labs she could use, and it's just been determined for whatever reason that the 4th floor lab is the one they'll give her.

    11% picked this

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