#11 - Plumb-Ace advertises that its plumbers are more

[Administrator]

Complete Question Explanation

Flaw in the Reasoning. The correct answer choice is (E)

The author suspects that the certification process for plumbers at Plumb-Ace is not very difficult, contrary to what Plumb-Ace may claim. As evidence, she points to the written portion of the certification exam, which almost everyone passes very easily. The stimulus contains an argument/counterargument structure, which can be summarized as follows:

Plumb-Ace Argument:

• Premise: Plumb-Ace plumbers complete a difficult certification process.
  
  Conclusion: Plumb-Ace plumbers are more qualified than other plumbers.

Author’s Counterargument:

• Premise: Almost all pass the written portion of the certification exam.
  
  Conclusion: The certification process is not very difficult.

Note that the first portion of the stimulus has almost no bearing on the issue at hand. This is partly because the author merely rejects Plumb-Ace’s premise, not its conclusion. In fact, the author explicitly refuses to make any judgments about whether Plumb-Ace plumbers are more or less qualified than other plumbers.

The argument is flawed because the author’s conclusion is based on a questionable premise—namely, that the written portion of the certification exam is representative of the exam as a whole. This is an example of an Error of Composition, the author attributes a characteristic of part of the group (easy written component) to the group as a whole (easy certification exam). This prephrase is crucial and quickly reveals answer choice (E) to be correct.

Answer Choice (A): This answer choice describes the error of Mistaken Reversal. Although the argument does contain elements of conditional reasoning (the certification process requires a written portion, for instance), the author never mentioned what would be sufficient to make the process difficult. Do not ever assume that there is a flaw in the conditional aspect of the argument just because a stimulus with elements of conditionality is followed by a Flaw question.

Answer Choice (B): The author explicitly discounted the issue of whether Plumb-Ace plumbers are qualified or not. This answer choice is incorrect.

Answer Choice (C): The fact that plumbers at other firms find it even easier to get certified than Plumb-Ace’s plumbers has no bearing on the issue of whether Plumb-Ace’s certification process is difficult. The author’s conclusion represents an absolute, not a comparative claim. She never argued, for instance, that Plumb-Ace plumbers complete the easiest certification process in the region. If anything, this answer choice describes an error in Plumb-Ace’s line of reasoning.

Answer Choice (D): This answer choice describes a classic error in the use of evidence: lack of evidence supporting a claim is taken as evidence that the claim must be false. No such error is committed here.

Answer Choice (E): This is the correct answer choice. The author presumes that since one part of a whole lacks a certain characteristic (the written portion of the certification exam lacks difficulty), the whole must lack that characteristic as well (the certification process as a whole is not very difficult). Do not be misled by the fact that our prephrase was a positive claim, not a negative one. The error is the same whether the characteristic in question is “ease” (positive) or “lack of difficulty” (negative).

[agroves]

Hello,

After using the process of elimination, I now know that AC E is correct. However, can you explain how you would arrive at this AC quickly without using the process of elimination? Is there any clear indicator in the question stem that would allow us to pre-phrase for answer E?

Thanks!

Angela

[KelseyWoods]

Hi Angela!

When you're looking for the flaw in this argument, you might notice that the argument assumes that just because nearly everyone passes the written portion of the certification exam then that means the entire certification process must not be that difficult. Essentially, since one part of the certification process is not difficult, that means the certification process as a whole is not difficult. You might not necessarily prephrase it with the part/whole terminology of AC E but you should be looking for an AC that describes that flaw in some way. Also, part/whole flaws are a fairly common type of flaw on the LSAT so you should always be on the lookout for them in your stimuli and when you spot a part/whole flaw, look for an answer choice that describes it.

That said, sometimes the process of elimination is the best way to find a correct answer. For some questions, it's just easier to get rid of the incorrect answers than it is to find the correct one!

Hope that helps!

Kelsey

[Applesaid]

hello!

I ended up choosing answer choice C incorrectly but I don't understand why this is a composition/division error. Does the flaw lie in the last sentence that nearly everyone who takes the written portion of the certification exam passes it very easily?


Celine

[Jon Denning]

Hey Celine,

Thanks for the question. The composition/division error here is the result of concluding that the entire certification process is not difficult, simply because one portion of it (the written portion) is not difficult (nearly everyone passes very easily). In other words, just because it is easy to pass the writing section, does not necessarily mean that passing the other portions is also easy. So the exam itself can be difficult, even if all of its portions aren't.

That leads to answer choice (E), where we point out that just because one part of the test lacks difficulty (writing), that does not prove that the whole lacks difficulty as well.

I hope that helps!

[katnyc]

I got the right answer E. As I saw part out of whole. I am wondering because for stimulus that have some conditional reasoning I tend to mess up. Would you mind going over a in detail please?

[KelseyWoods]

Hi katnyc!

Technically, yes, there's a conditional statement in this stimulus ("must"). However, the structure of the argument does not really rely on this conditional reasoning. In other words, the author does not arrive at the conclusion by using conditional logic.

In general, with arguments, the most important thing to consider is how the premises support the conclusion. Sometimes conditional statements are an integral part of this support. Sometimes there are conditional statements but they are not integral to supporting the conclusion. Always start with 1) what's the conclusion? and 2) how do the premises support the conclusion? That will help you determine how important conditional logic is to an argument.

In this case, the author's conclusion is that the certification process is not very difficult because the written portion of the exam is not difficult. That's using something that's true of a part and concluding that it's true of the whole. No need to get into any conditional aspects here.

Check out this blogpost that goes into more depth about when to diagram and use conditional reasoning on the exam: https://blog.powerscore.com/lsat/bid-33 ... o-diagram/

Hope this helps!

Best,
Kelsey

[lemonade42]

Does this mean that "because" is not a premise indicator? So in this case, it says "because" to show that the process is not difficult since one of the ways that it can be difficult is through the easy written portion. Instead of: the process is not difficult which requires always the condition that the written portion is easy.

[Dana D]

Hey lemonade,

I would not rely on indicator words alone to identify premises, but in this case yes, "because" is indicating a premise. You can think of these as separate ideas - there is a claim (that the certification process is not very difficult) and then there is a premise to support that claim (nearly everyone who takes the written portion passes it very easily).

"But" is also indicating a premise in this sentence, which is why we don't want to just rely on indicator words. The author says "Plumb-Ace plumbers may or may not be more qualified." Well, what's the justification for thinking that? "The certification process is not very difficult." And, as we just discussed, the premise for that claim is that the nearly everyone passes the written exam.

Hope that helps!