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## Must Be X vs Cannot be True

General questions relating to LSAT Reading Comprehension.
sofcu23
• Posts: 5
• Joined: Jun 21, 2022
#95918
Hi,

I'm working on the except and least identify the question stem mini drill on page 44 of lesson 2's homework " RC question types".
What is the difference between MustX and Cannot be True questions? Aren't they both asking to identify something that cannot be true?
Or is the difference in the strength of "must" vs. "can".

Thank you,
Sofía
katehos
• PowerScore Staff
• Posts: 184
• Joined: Mar 31, 2022
#95986
Hi Sofía, thank you for your question!

The difference between Must Be TrueX and Cannot Be True questions stems from the nature of the correct and incorrect answers.

In a Must Be TrueX question, you will have 4 incorrect answers that Must Be True, with 1 correct answer that is Not Necessarily True.

In a Cannot Be True question, you will have 4 incorrect answers that Could Be True, with 1 correct answer that Cannot Be True.

As you can see, they're not both asking you to identify something that Cannot Be True, since Not Necessarily True is distinct from Cannot Be True.

This distinction is further explored in posts such as this one that discusses Logical Opposition (viewtopic.php?t=7011), as well as this one that further explains your specific question (viewtopic.php?t=2772).

I hope this helps!
Kate
bjohnson2021
• Posts: 7
• Joined: Jul 03, 2023
#102487
Hello,

I am still struggling with this concept as well. Specifically the following two question stems:

1) "It can be inferred from the passage that each of the following was achievable before the rise of modern computing EXCEPT:" --- I kind of understand why this is a Cannot question since it is asking what cannot be inferred (the word infer is the clue to cannot)

2) "The passages provides information intended to help explain each of the following EXCEPT:" --- I don't really understand why this is MustX instead of Cannot. I was thinking that "intended to help explain" is similar to making an inference and would therefore be a Cannot question

These question stems are from the RC workbook, so I am not sure the passages that they come from. They are part of the "EXCEPT and LEAST Identify the Question Stem Mini-Drill" set. Any help is appreciated. Thank you in advance
Dave Killoran
• PowerScore Staff
• Posts: 5813
• Joined: Mar 25, 2011
#102496
Hi B,

Thanks for the questions. Just fyi, we cover RCB Workbook questions here: viewforum.php?f=1383

Looking specifically at what you've asked, let's isolate each:

• 1) "It can be inferred from the passage that each of the following was achievable before the rise of modern computing EXCEPT:"

In the above, I highlighted the key words to solving this one. Note that "infer" is not one of those words, which I'll address at the end.

First, "was achievable" suggests that it could happen. so, the question stem is saying each of the following could happen, and then pairs that with Except at the end. That means 4 Could occur, and one Cannot occur, so this is a Cannot Be True question.

Second, the use of "infer" here is tricky but no actually determinative. It really means "it must be true that these could occur," which is still just a Could question form. You see them do this on occasion--LG is more likely where it occurs--but it does happen. In this case, we could restate the question as, "Each of the following could occur EXCEPT" and have the exact same result, which is why this is a Cannot question.

And then the other one:

• 2) "The passages provides information intended to help explain each of the following EXCEPT:"

The "provides information" is the idea of whether the information is there or not. So, 4 of the answers must have the information needed, which is Must. Then the Except flips it to MustX.

We could restate this along the lines of "Each of the following must be explainable EXCEPT," which is MustX.

Since this is the Workbook, these are hard and designed to make you think. It also means they occur only rarely, which is the good news! Thanks!
bjohnson2021
• Posts: 7
• Joined: Jul 03, 2023
#102497
Dave,

Thank you so much for your response. It was very helpful. Sorry about posting in the wrong place. I couldn't find the forum for the workbook. Thank you for linking it.

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