Prep Test #31, June 2000, Section 2, Problem 21 Forum

[john2018]

Can somebody explain to me why (c) is the correct answer? Moreover, can somebody point out where BOTH of the logical flaws in the argument are? I only see one, a mistaken reversal. Thank you so much!

[CardozoLaw09]

Sure

Mistaken reversal is the flaw - good job identifying that

In the stimulus,

The mistaken reversal occurs when the author concludes that Alicia knows the bank deposited was credited on the date of the transaction from the premise that Alicia knows the bank deposit was made before 3PM. However, the condition given in the stimulus is the other way around ie) Credited ---> Made before 3 P.M.

The author mistakenly concludes that because it was made before 3 PM it was credited on the date of the transaction (Made before 3PM ---> Credited).

In answer choice C, we see the same flaw being exhibited

The conclusion is that George knows he will be promoted to shift supervisor based on the premise that Helen will resign. However, the condition is that George will be promoted only if Helen Resigns; or, Promoted ---> Helen Resigns.

Thus, C also commits a mistaken reversal by saying, Helen is resigning, therefore George knows he will be promoted (Helen Resigns ---> George Promoted)

Hope that helpls

[Christine (MLSAT)]

Hey john2018!

You're right that the first flaw is a mistaken reversal of a conditional. The SECOND flaw is a problem of knowledge.

Let's remove the mistaken reversal for a second.

All turtles wear shoes. Joe knows Snappy is a turtle. Therefor Joe knows that Snappy wears shoes.

Well, since Snappy IS a turtle, we (the omniscient reader) know that Snappy IS wearing shoes. But does Joe know about this rule? I don't know what Joe knows! Maybe he's never heard that rule before, so even though the rule is true, Joe has no idea whether Snappy wears shoes!

In this argument, even if the rule leap were valid, we've never been told that Alicia knows about the rule. The same knowledge leap occurs in (C). Even if that rule about promotions actually worked, we have no idea whether George knows about it.

Does that help a bit?


ETA: I imagine that you were frustrated because both (A) and (B) commit mistaken reversal. The only thing those answers are missing is the knowledge flaw!

Notice that (D) picks up on the problem of belief/knowledge. (E) does as well, and adds in an assumption connecting knowledge and desires.

While double-flaw parallel questions are rather uncommon, when they do appear, it is typical for 2 wrong answers to only have the first flaw, and the other 2 wrong answers to only have the second. Thus, identifying only one of the flaws will generally leave you frustrated between three answer choices!

Strategically, though, you can occasionally use those other answers to point you in the right direction. If you'd noticed that (D) and (E) both had issues of knowledge and belief, that might have sparked your curiosity about whether the same applied to the stimulus. Looking back to it with that in mind might have made you more sensitive to the words "Alicia knows".

What do you think?

[john2018]

Sure

Mistaken reversal is the flaw - good job identifying that

In the stimulus,

The mistaken reversal occurs when the author concludes that Alicia knows the bank deposited was credited on the date of the transaction from the premise that Alicia knows the bank deposit was made before 3PM. However, the condition given in the stimulus is the other way around ie) Credited ---> Made before 3 P.M.

The author mistakenly concludes that because it was made before 3 PM it was credited on the date of the transaction (Made before 3PM ---> Credited).

In answer choice C, we see the same flaw being exhibited

The conclusion is that George knows he will be promoted to shift supervisor based on the premise that Helen will resign. However, the condition is that George will be promoted only if Helen Resigns; or, Promoted ---> Helen Resigns.

Thus, C also commits a mistaken reversal by saying, Helen is resigning, therefore George knows he will be promoted (Helen Resigns ---> George Promoted)

Hope that helpls

Thanks for the quick reply. But let me rephrase. What makes (c) correct, but (a) and (b) incorrect?

In (a), I see:
Permitted to ask Questions --> Journalists
Marj is Journalist --> Permitted to ask questions
Mistaken reversal, no?

In (b), I see:
Patrick works --> Thursday
Thursday --> Patrick Works
Mistaken reversal, no?

So what makes (c) correct? I know it's a mistaken reversal, but, as the question stem states, where are 'both'--e.g. two--logical flaws in the argument? I think that this is what separates (c) from the other mistaken reversals, but I just don't see it. Thanks so much for your help!

[CardozoLaw09]

See above

[john2018]

Hey john2018!

You're right that the first flaw is a mistaken reversal of a conditional. The SECOND flaw is a problem of knowledge.

Let's remove the mistaken reversal for a second.

All turtles wear shoes. Joe knows Snappy is a turtle. Therefor Joe knows that Snappy wears shoes.

Well, since Snappy IS a turtle, we (the omniscient reader) know that Snappy IS wearing shoes. But does Joe know about this rule? I don't know what Joe knows! Maybe he's never heard that rule before, so even though the rule is true, Joe has no idea whether Snappy wears shoes!

In this argument, even if the rule leap were valid, we've never been told that Alicia knows about the rule. The same knowledge leap occurs in (C). Even if that rule about promotions actually worked, we have no idea whether George knows about it.

Does that help a bit?

Epic. That is exactly what I was looking for. Thank you very much! Makes perfect sense now.