Complete Question Explanation
Justify the Conclusion—PR, SN. The correct answer choice is (B)
This stimulus provides a principle and its application. The principle takes the form of a conditional rule with a three-part, compound sufficient condition. The application informs you that just one of those sufficient conditions has been met, but then concludes that the necessary condition must be satisfied.
The conditional principle is a rule used to determine whether someone with overdue library books must be fined. There are three sufficient conditions, and if all three are satisfied, then the person must be fined. The three conditions are: 1) the person has more than one book overdue at the same time; 2) some of the overdue books are not children’s books; and 3) the person has been fined previously for overdue books.
We can diagram this rule as:
1+ = more than one overdue book at the same time
CB = some of the overdue books are not children’s books
PBF = person has previously been fined for overdue books
Fine = the person must be fined
The application tells us only that Kessler currently has three overdue library books, saying nothing about the other two sufficient conditions, yet concludes that Kessler must be fined.
The question stem provides that this is a Justify the Conclusion question. Our prephrase is that in order to justify the application, the correct answer choice will have to provide the remaining two sufficient conditions, namely that some of the overdue books are not children’s books, and that Kessler has been previously been fined for overdue books.
Answer choice (A): This answer choice is incorrect, because it leaves open the option that Kessler’s overdue books might all be children’s books. While this choice says that “some of the books that Kessler currently has out on loan from the library” are not children’s books, it may be the case that all of the overdue books are children’s books.
Answer choice (B): This is the correct answer choice, because it provides the remaining two sufficient conditions. One of Kessler’s three overdue books is not a children’s book, and he has been fined in the past for having an overdue book.
Answer choice (C): While this answer choice tells us that Kessler has previously returned books late, it does not tells us that Kessler has previously been fined for overdue books.
Answer choice (D): This answer choice tells us that Kessler has been fined in the past for overdue books, but does not tell us whether any of Kessler’s books that are currently overdue are not children’s books.
Answer choice (E): This answer choice explicitly provides that Keller has not previously been fined for overdue books.
#22 - Principle: Anyone who has more than one overdue
Could you please explain why answer A is incorrect here and B is the correct answer. The answer guide shows that only 33% got this question right and 33% picked A like I did, so I want to figure out why I was tricked. I think it has something to do with the with difference in "some of the books are not children's" in A and "one of the books is a novel for adults" in B, but I am not sure why? Could you explain this please?
This one is really tricky. I can see why you picked A!
What they're trying to slide past you here is "Some of the books that Kessler currently has out on loan from the library are not children's books", which they are trying to make you read as "Some of the overdue books that Kessler currently has out on loan from the library are not children's books". It could be, from A, that all of Kessler's overdue books are still children's books (other types are on loan, but not late), and thus the principle may not apply.
B has both parts of the principle: one of the overdue books is a novel for adults (not children's book) and he's been fined for it being late before. Given how attractive A looks, though, it's no coincidence that it was put right next to B - it's an intentional distraction. The LSAT is fun like that!
Hope that helps,
Edited 6/14: Jon D
Okay, thanks, that clears things up for that question.
But I thought, in these compound sufficient condition scenarios, you don't need both (or all 3) sufficient conditions for the necessary condition to be true?? As in, just one of the sufficient conditions being true will suffice for the necessary condition to be true ?? I've had several PS instructors reply to me here on other question threads saying this !!! i can copy & paste them !!1 i hate these kind of questions ugh !!
FOR ONE EXAMPLE, look at David Boyle's explanation in PrepTest 69 / June 2013, LR Section 4, #21 !!!!!
These questions can certainly be tough!! The key here is that it is a justify question, meaning we need to make the conclusion (that Kessler must be fined) absolutely, totally, 100% true.
Since being fined is the necessary condition, the only way to justify that Kessler must be fined is to fulfill all three sufficient conditions. I think what you're talking about is general to conditional rules, when a necessary clause can be true without all of the sufficient rules being true. However, since this is a conditional rule that uses "and", the only way to make the necessary certainly true is to fulfill all three sufficient requirements.
If the principle had said, "or", as in "Anyone who has more than one overdue book must be fined if some are not children's books or if he's been fined previously", then we only need one or the other. In this case however, all of the sufficient requirements needed to be fulfilled in order to justify the conclusion.
Hope this helps!
This is seriously a joke. I know the powerscore book said that there were some funny things they did with "some" and "all" and "not some"... but I don't remember seeing a question like this. I mean this is the most ridiculous perversion of the English language.
Moreover, the more I read about it, the less I understand. I read the "administrator" explanation and thought oh, ha ha... right, because if "some are not children's books" "all of them could be children's books"... because "all" is not "some"? Which is totally totally ridiculous.
But then I read the other post by Lucas, and he says "none of the books could be children's books and then the principle would not apply."
WHAT?! Which is it? Does anyone know?
Hey peterius - thanks for the question! Let me see if I can jump into the fray here and (hopefully) clear this thing up
Before I do let me note though that Lucas misspoke above. He said "It could be, from A, that none of Kessler's overdue books are children's books. [emphasis mine]" What that should say is ""It could be, from A, that all of Kessler's overdue books are children's books." Subtle difference, but a crucial one: if all the books overdue are children's books, THEN the principle wouldn't necessarily apply. In other words, just because Kessler has non-children's books on loan DOES NOT mean those are the three that are overdue. Sorry about that. I've edited Lucas' reply to fix that mistake.
That hopefully settled, let me take a fresh stab at a full explanation, for you and any other readers of this thread that are similarly at wit's end
First, you're spot on to note that LSAC loves, LOVES to play language games, and as the questions get harder—which is for sure what you should expect once you've reached #22 in an LR section—this tactic ratchets up to high gear. So while it can be super annoying to wade through the intentional (and often unnecessary) convolution that permeates tough LR questions, not only can it be beaten, but the first step to beating it is awareness. Kudos there.
Now let's look at this question. Note: I'm writing this as my own, personal take, and not referring back to anything above (since you've read the previous comments and you're still feeling stuck). I can't imagine I'll say anything contradictory, but I'm not attempting to weave prior explanations into this one in hopes that it adds something new and revealing.
The Principle is a doozy, but fortunately I think we can simplify the language quite a bit, in part by reframing a few of the qualifying statements (the "more" and "some" stuff) to easier, synonymous ideas, and in part by recognizing a consistent element to each sufficient piece that makes it easier to see when the governing rule applies. I'll explain.
This is all about who should be fined for overdue library books. That is, a scenario/circumstance in which we are told a fine is appropriate (note that this isn't necessarily the only situation where someone should be fined, but merely one, possibly of many, where a fine is said to be the right move). So what are the conditions that lead to a fine?
(1) 2+ books overdue (that's the "more than one" at the outset)
Then we jump to the "if" part (remember that "if" starts the arrow relationship) and see that
(2) 1+ overdue not children's (that's the "some...are not")
(3) Previously fined for overdue
So in each I've tried to make the language a little easier to process and apply to new situations. That's what you want from a conditional principle, the ability to see when it applies and when it might not. "One late book not children's"? (2) fits. "Ten late books not children's"? (2) still fits. And so on.
I've also recognized that each is all about "overdue books:" multiple books out late, a least one late not for children, previously fined for late books (to paraphrase). So that consistent piece needs to be in whatever specific situation we try to apply this to! Without it we can't know for sure whether the Principle is relevant.
So what can we do with the Principle? From it we know a number of things conditionally, but the three key truths are:
The only way to know for sure someone should be fined is if we can first know all three of those above.
If we don't have all three of those ideas in play, we're stuck. We know nothing. We can't start the chain
without all three.
If someone isn't fined then at least one of those three didn't apply/occur. That's the contrapositive.
The Application says Kessler should be fined. Time to play the matching game! The Application already tells us that Kessler has three overdue books out, so (1) above is satisfied. Now let's just run through the answers finding four that fail to give the other pieces, (2) and (3) above.
(A) We don't know that the non-children books he has out are the overdue ones, so we don't have (2) above. That is, it could be that Kessler's three late books are all children's books. Other books on loan to Kessler aren't children's...but also not overdue. Like I said, without "overdue" the Principle may not apply.
(B) One late book is for adults, meaning "1+ overdue not children's," which is (2) above (and yes it's safe to say adult books and children's books are different). Kessler was also "previously fined for overdue" books, which is (3) above. Bingo! We have all three pieces, so Kessler must be fined.
(C) We don't know Kessler has ever been fined, so we're stuck.
(D) We don't know whether any of Kessler's three late books are for children or not, so we're stuck again.
(E) This fails (2) since we don't know what kind of books he has out that are overdue, and (3) because he's never been fined. Either would be enough to stop us in our tracks. Stuck again.
So yes, the language here is tricky. But I'm happy to report that this is legitimately about as tough as the test will get (they can play on variations of this but there's only so much difficulty/confusion they can inject), and with a little practice this sort of thing becomes infinitely clearer.
Until then though I hope I've added some clarity to this particular question
Let me know if that helps!
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Hi thank you for all the explanations, I still can't understand why B is correct, because, "more than one adult books" must be overdue, and yet, B only assures us that ONE of the overdue books is an adult book, which does not satisfy "more than one" adult book requirement....
right?? am i missing something???
Thank you for your help!!
The principle in the stimulus is as follows:
More than 1 book overdue AND at least one adult book AND previously fined impose fine.
What we know is that Kessler has 3 overdue books, and we are trying to prove that the library should impose a fine.
Answer choice A establishes that at least one of those books is an adult book and that Kessler has previously been fined, satisfying all of the conditions sufficient to impose a fine.
What happened to you is that you matched the "one adult book" to the "more than 1 book overdue." We had already satisfied the "more than 1 book overdue" condition (3 books), and "one adult book" satisfies the "at least one adult book" condition.