Q24 - No one who works at

[samuelfbaron]

I cannot determine why (D) is the credited response! Anyone care to aid in an explanation?

content deleted for copyright reasons

I selected (C) but (D) is the credited response?

How would you solve this in a test situation?

[timmydoeslsat]

I cannot determine why (D) is the credited response! Anyone care to aid in an explanation?

I selected (C) but (D) is the credited response?

How would you solve this in a test situation?

This is classic flawed reasoning.

Not both B and C.

~B

Therefore, C.

This does not have to be true. We could have both not be present. To say that both cannot happen does not mean that one must happen.

The stimulus states that we know not both PE and R. We also know ~R. So we have already met the condition that is required of us. We know that both PE and R will not happen, as we have ~R. The argument, invalidly, claims that we have PE.

A) Valid argument
B) Valid argument
C) Valid argument

D)

~OH
Not both OH and R.
We conclude R.

Same faulty reasoning. We could just as easily conclude ~R as it too would be consistent with the premise of not both OH and R.

E) Valid argument.

Typically you can identify the strong candidates by their conclusions on these matching questions, but this one cannot be done that way with similar conclusions.

[bbirdwell]

Yes! I think the key from timmydoeslsat's response is this:

To say that both cannot happen does not mean that one must happen.

It is, indeed, classic flawed reasoning. You can think of it in an "LSAT games" way if you like:

Imagine we have the rule "B and C cannot both be in."
This would be symbolized: B --> ~C, C --> ~B.

Notice that having one "out" does not lead to any other conclusions!

[ptewarie]

Put in simple terms whenever you see parallell questions:

Stimulus:

Premise: if A-> NOT B AND NOT C

conclusion:So if NOT B then NOT C

doesn't make logical sense, since in the first instance, both B and C are necessary conditions of A, in the conclusion they are seen as
C-->B which is a completely different conditional linkage.


Answer choices:

A is flawed too, but it is not parallel:
it says:

A-> NOT B and NOT C

Since C-> NOT B

That is different( C is positive, in conclusion)

D: you need to re-order the sentences here(conclusion and premise must be separated), but once you order them properly you get the following:

A-> NOT B AND NOT C
NOT C -> NOT B

Exact same as the premise!

Note, you have to reorder it:

"No one who lives in a house both owns it and pays rent on it.

My next door neighbors do not own their house( sentence 1)

So it must be that my next-door neighbors pay rent on their house

[timmydoeslsat]

Premise: if A-> NOT B AND NOT C

conclusion:So if NOT B then NOT C

doesn't make logical sense, since in the first instance, both B and C are necessary conditions of A, in the conclusion they are seen as
C-->B which is a completely different conditional linkage.

I disagree with your interpretation here.

The premise is: X ---> ~ [A and B]

To say not both A and B is different than to say [~A and ~B]

Our argument:

X ---> ~ [A and B]

And we know of ~A occurring.

So we have satisfied our premise, yet the author confuses what our stipulation is. The author concludes we must have B occur. The truth is that we could have B or ~B occur, it is of no matter at this point.

[hovaLSAT]

how do we assume that Lester works at Leilas? Shouldnt they say Lester, who works at L...etc". That was problematic for me especially because the answer choices were phrased in ways that made it clear that they were part of the group under examination/ fit the qualifications..

[csunnerberg13]

I second hovaLSAT's question and also - could someone show why B and D are different? I got down to these two - and from what I can see above B is correct reasoning - but I don't see the difference between the two.

[christine.defenbaugh]

Very interesting question hovaLSAT and csunnerberg13! There are two answers I'll give you, one more useful than the other.

First, I would actually argue that none of the answer choices do make it perfectly clear the neighbors are in the 'anyone who lives in a house' category. This is almost unforgivably pedantic of me, but we only refer to 'their house' - that could mean they live in it, but it could also simply mean they own it or pay rent on it while living elsewhere. As such, we could think of this disconnect as one more flaw.

But the second, more important answer to this question is: it doesn't matter. Why? Because even if this is a disconnect between the stimulus and the answer choice, it's a disconnect present in every.single.answer. So we can safely ignore it, because it does not differentiate the answers.

As for the difference between (B) and (D), the critical difference is that the premise-fact given is a positive in (B), and a negative in (D). I'll lay out my shorthand for each answer below. Note that every answer gives:
1) a conditional rule
2) a fact premise
3) a fact conclusion

STIMULUS:
LE --> ~PPE or ~R
Lester = ~R
Lester = PPE

CORRECT ANSWER (D):
LH --> ~O or ~R
neighbor = ~O
neighbor = R


INCORRECT ANSWER (A):
LH --> ~O or ~R
neighbor = R
neighbor = ~O


INCORRECT ANSWER (B):
LH --> ~O or ~R
neighbor = O
neighbor = ~R


INCORRECT ANSWER (C):
LH and ~R--> O
neighbor = ~R
neighbor = O


INCORRECT ANSWER (E):
LH and ~O--> R
neighbor = ~O
neighbor = R


Notice that (A) and (B) are logically equivalent. They are both 'you can't do both' structures. We know one element is true, so we know the second one can't be.

(C) and (E) are similarly equivalent. This time it's a 'you have to have at least one' structure. We know one element is NOT true, so we know the second one must be.

The stimulus and (D) have a 'you can't have both' structure, but our premise fact is that one of the two has NOT happened. They then conclude, incorrectly, that the other element must have happened.


Please let me know if you have any questions about how each of these answers were translated!

#officialexplanation

[lovisa.lloyd]

Hi all!

I made an account here specifically to share how I got to the correct answer. I initially got it wrong after getting very stumped and worked through several diagramming options before arriving at what I think is the simplest and quickest method.

My diagramming looks a little different from above so if it's incorrect, please let me know.

Questions like this tend to stump me/stress me out/frustrate me cause they can take so long! But this one is really not any tougher than other flawed reasoning questions, it just has more complex prose.

I think we can use the 2-way arrow technique here to simplify the diagramming a bit. Doing this knocked out the use of one whole variable for me, so I was only working with an X and Y instead of X, Y, and Z.

As was stated above, there is indeed a logical jump where we must assume that Lester works at the store, since all of the answer choices assume the neighbors live in their house. That's not the issue at hand here. In fact, making this assumption let me reduce the variables to 2 which makes diagramming/checking go much faster.

Stimulus:

x = PPE
y= raise

Principle: x <--|--> y (if x, not y : if y, not x. if raise, not PPE : if PPE, not raise. Can't have both, but could have neither.)
Application: /y --> x (you actually don't need to worry about why this is wrong, but it's wrong because the only way to get y on the left is to make x's contrapositive, and the contrapositive of x --> /y is y-->/x)

So we're looking for a principle/application relational flaw that is most similar to the above (x <--|--> y, /y-->x)


Answer choices:

x = own
y = rent

A)
Principle: x <--|--> y (if own, then not rent. if rent, then not own - identical principle to stimulus)
Application: y --> /x (this is not flawed reasoning, it's correct reasoning)

B)
Principle: x <--|--> y (if own, then not rent. if rent, then not own - identical principle to stimulus)
Application: x --> /y (once again, this is not flawed reasoning, it's correct reasoning)

C)
Principle: /x --> y (if not rent, then own. principle already looks way different than what we're looking for.)
Application: /x --> y (not renting, must be owning. not a flaw, a correct application of the principal. however we can see that neither the principle nor the relationship between principle and application looks anything like our stimulus.)

D)
Principle: x <--|--> y (same principle as the stimulus and the first two answers - if own, not rent/if rent, not own)
Application: /x --> y (winner, winner, chicken dinner. this is actually the exact same flaw as the stimulus, just reversed)

E)
Principle: /x --> y (if not own then rent. as in C, the principle here already looks way different than what we're looking for)
Application: /x --> y (don't own, must rent. not a flaw, a correct application of the principle.)

Diagrammed this way, D is a perfect and obvious match for the stimulus principle as well as the flaw (which is important because seeing the relationship between them is crucial to getting this question right):

Stimulus: x <--|--> y, /y-->x
Answer D: x <--|--> y, /x-->y

Hope this helps someone who was as stuck as I was!

[anthonyagostino]

I wrote something out then hit the wrong button. Not in the mood after fighting this question for so long only to realize the answer may be closer than we made it out to be.

Think SIMILAR. Not identical..remember they said similar. Logic flaw/ difference....Just because you can't have a dog AND a cat, does not mean you can't have a dog OR a cat. We get confused because we get snagged in the content and it's familiarity. The words appears familiar so we ASSUME the way the answer should feel. It doesn't matter how FLAWED the argument as long as the two of them are FLAWED SIMILARLY. The problem is we get stuck of what aspect of the argument is suppose to be similar...The math, the choice of words, the units (percentage to quantity), the time frame......Here we think it's a logical argument and the flaw is in the math...some are mathematically correct. The problem is.... the conclusions ARE WORDED DIFFERENTLY. .....except for D.

Last sentence in Premise= So it must be that he has received a poor performance evaluation

A- Last sentence----- THEY DO NOT OWN IT. (Notice A and B switch places, they work out mathematically so something must be different)

B- Last sentence----- THEY DO NOT PAY RENT ON IT. (Notice A and B switch places, they work out mathematically so something must be different)

C- Not worded, not structured, not written in any way similar. They switched grammatically from NO ONE to ANYONE. That in LSAT world is a bust. It is so different. Among other things that make this a bust. Also notice the difference between " own it and rent it " and "owns it and rents it." They sound similar but in grammatical construction they are different. As is the difference between rents it and pays rent. I can tell you as a landlord, just because a tenant rents something......doesn't mean they pay the rent. Remember law school, lawyer.... they are here to splitting hairs. This is why English majors do so well in Law School. ( I aint one...I promise that) Notice he said they have not paid any rent...Is not the same as do not rent it but concludes that since they do not rent it. NOT THE SAME.

D- Follow me here. Going on a limb.
In D it says " Since no one who...." Grammatically similar to the Premise of "No one who.." and if you notice Grammatically similar to A and B, that is probably why they did that. It is relevant. Just like imperative statements imply the YOU as in Stand up means You stand up. Then No one, and Since no one are the same.

No one who-- lives in a house----------------------------------- both--- owns---------- it--------and-----pays rent on it.
No one who-- works a Leila's Electronics has received- both--- (owns/ has)- a ppe- and-----a raise.

My next door neighbors---- do-----not---- own their house.
Lester------------------------------ has----not--- received a raise.

It must be that---- my next-door neighbor------ pay rent on the house (stated in a positive as in must have a ppe)
it must be that----- he----------------------------------- received a poor performance evaluation.


If it is true that ( 1+ 2) is the same as (2+1) then not (both own it and rent it) is the same as not (both rent it and own it)
not received (both a poor performance evaluation and a raise) is the same as (received a raise and a poor performance evaluation)


Think that the LSAT authors warned that you would have to stay on task and be able to shift gears and look at problems from different perspectives. Yes the math may or may not be correct when you consider the difference but at the end of the day.....
AB and D have many similar components. There has to be a differentiating factor...what is it.