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#31739
Please post below with any questions!
 roselsat123
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#32161
I get very confused with parallel flaw questions. Can you explain this question and answer?
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 Jonathan Evans
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#32195
Complete Question Explanation

Parallel the Flaw. The correct answer choice is (E)

Many students find Parallel questions challenging, and for good reason! There's a lot to keep track of, and the questions themselves can be rather long and time consuming. Therefore, it's in your interest to try to simplify the process as much as possible by extracting salient features in the stimulus that will enable you quickly and accurately to eliminate incorrect answer choices. In a way, Parallel the Flaw questions can be somewhat more straightforward than Parallel the Reasoning questions, for one simple reason: your primary task in Parallel the Flaw questions is to match the flaw. In Parallel the Reasoning questions, there are more potential moving parts that you might have to account for. Thus, you must focus on the flaw. Knowing common flaws and patterns can help.

In this stimulus, we know:
  1. Lucinda will be matriculating at National U as an Engineering major.
  2. Residents of Western Hall :most: Engineering majors
  3. Conclusion: Lucinda will probably be a Western Hall resident.
Focus on why you don't have adequate support for the conclusion: Even though most residents of Western Hall are Engineering majors, you do not know that most Engineering majors reside in Western Hall. This is a quantifier shift fallacy and is a concept related to a Mistaken Reversal™ or fallacy of the converse. It could be that most Engineering majors reside elsewhere.

To prephrase, you will be looking for an answer choice in which:
  1. Something/someone :arrow: X
  2. Z :most: X
  3. Conclusion: Something will likely be a Z
In natural language, you could simply predict:
  • Just because something/someone is an X and most of Z are X, we don't know that something/someone will be a Z.
Answer choice (A): A shopping mall (something) is "coming to our city." Now we will be a city with a major shopping mall (X). Most cities with major shopping malls (X) are major economic hubs (Z). Conclusion: our city with a major shopping mall (X) will likely be an economic hub (Z). This answer choice reverses the Mistaken Reversal™ to make a far stronger argument. Not a match.

Answer choice (B): You can dispense with this choice without digging too far into the weeds. There is no consideration of something not happening in the stimulus. Knock it out and move on.

Answer choice (C): Again, great opportunity to make a quick strike here. There is no consideration in the stimulus of something always happening/being true. Mismatch in strength of likelihood makes this an automatic incorrect answer.

Answer choice (D): Three in a row with pretty obvious disconnects. We have a time mismatch here: Something happened a while ago. Something happened since then. We can conclude something about other, similar stuff. Standard exceptional case fallacy (a faulty generalization). Not what we have in the stimulus.

Answer choice (E): This is the correct answer choice. In a common Parallel question answer choice strategy, this choice challenges students by mixing up the order of the statements. Changing the order of the statements in an argument without changing the underlying structure of the argument does not modify the reasoning. Most cities that are big economic hubs (Z) have (X). Our city (something) is going to get (X). Conclusion: Our city will likely become a (Z). Perfect match, with statements (1) and (2) flipped.
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 mtdaniel
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#99125
This was one of only two questions I missed in this section. I didn't read the stimulus close enough and my brain went looking for something that would be logically correct and ended up choosing (A).
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 Jeff Wren
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#99146
Hi mtdaniel,

The only thing that I will add to Jonathan's explanation above is that this argument uses formal logic. Formal logic basically expands on conditional reasoning by adding "most" and "some" statements to the "all" and "none" statements that also show up in conditional reasoning.

There used to be more formal logic on the LSAT, but these days you may not get any on your exam, maybe get one LR question. Even so, I recommend that students study it if they have the time (although it shouldn't be a priority over more frequent topics like conditional and causal reasoning).

This particular argument is pretty straightforward. All that you really need to know is that the term "most" is not reversible, and that is what the argument tries to do. For example, while it is true that most law students in the US are women, it is not true that most women in the US are law students.

This is a common flaw that comes up in formal logic and recognizing it makes the question much easier.

Formal logic is discussed in the lesson 8 homework online for PowerScore course students and also discussed in chapter 13 of the Logical Reasoning Bible.

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