Q10 - the city should not build incinerators

[sissixz]

Why A is wrong?

"Because less trash will be recycled if an incinerator is built". so I think A sounds right, for it seems if you not burn trash, trash then can be recycled.

And for D, I thought about it, and "any" seems too extreme, while "All" in A is also not seems right.

Someone please help me, thanks!!!

[jiyoonsim]

Not sure whether how I tackle this problem is the best,
but here's how I "guessed" on it.
Here's how I put the stem into simple experssions:

==

Incinerator -> waste rsrc -> wrong
Recycle -> waste rsrc drops
-----
Incinerator -> recycle drops

==

The conclusion is about incinerator and recycle,
and incinerator and recylce share "waste rsrc."
A mentions nothing about this common denominator, but D does.

Going a bit further, according to the flow of stem, we can say:

Incinerator -> waste rsrc -> recycle drops

And the contrapositive is

~recycle drops -> ~waste rsrc -> ~incinerator

D says this, except the ~recycle drops part.

I was pretty confused on this one too, so if anyone has some other/better explanation, please share!

[sissixz]

I looked it again, and I thought may be it is just about the conclusion.

the last sentence writes" if an incinerator is built, then less trash will be recycled"

then it followed:" if we want more trash to be recycled, then we should not build an incinerator" and that's just as the author said in the ends.

and "more trash to be recycled"=to avoid waisting resc, as the premise mentioned.

So it's D.

Now I don't think A is right. It's too extreme, may be some trash will neither be recycled nor burned, just buried, though small part.

Well, not that sure about my reasoning, waiting for more views.

[ManhattanPrepLSAT2]

For a question like this one, the right answer is not necessarily predictable, and so generally you'll end up working backwards to justify an answer.

Here's how I'd justify (D) --

Per the argument, if you burn huge amounts of trash in an incinerator, it is a waste of resources. Therefore, to avoid wasting resources, we should not burn huge amounts of trash in an incinerator.

Analogous argument: Spending hours playing video games is a huge waste of time. So, if one doesn't want to waste time, one cannot spend hours playing video games.

(A) is too absolute -- we don't have any proof that all non-recycled trash goes to incinerators -- knowing less trash will be recycled if an incinerator is built is the closest we've got, but that's far from enough.

[Dmitriy.Oziransky]

The contrapositive of D: If huge amounts of trash are burned, then the city is wasting resources. This is stated in the first sentence of the stimulus. Does that help?

[ManhattanPrepLSAT2]

very smart dmitriy - thanks for chiming in!

[daijob]

Hi, I just wanted to double check...

So E is wrong because the argument is Burn->waste,
and E says~Burn->-waste, so it takes the conditional statement wrongly, correct??
Similarly, D is correct because it is just the contrapositive of what the argument says, correct?
It does not have conditional statement directly but I felt the statement is kind of similar as conditional statement...
And, is it the case that not every sentences are important to choose a choice? Sometimes it seems we only need a or two sentences to choose correct answer.

Thank you,

[tommywallach]

Hey Dai,

Just wanted to let you know that the LSAT Experts only answer questions from students (people who bought a class or a book--you can tell them from their green or blue names on the forum, as opposed to orange). Other students might answer you, but you'd have to change your status to get expert answers to the questions.

Thanks!

-t

[daijob]

Hi,

So I have registered the books I have...
I would really appreciate it if anyone could answer my questions I would copy&paste it again.

So E is wrong because the argument is Burn->waste,
and E says~Burn->-waste, so it takes the conditional statement wrongly, correct??
Similarly, D is correct because it is just the contrapositive of what the argument says, correct?
It does not have conditional statement directly but I felt the statement is kind of similar as conditional statement...
And, is it the case that not every sentences are important to choose a choice? Sometimes it seems we only need a or two sentences to choose correct answer.

Thank you,

[maryadkins]

Yes all around. Good.

[olaizola.mariana]

I thought the word "any" made answer (D) too extreme, especially because the question asks for an answer that allows the argument to be "properly inferred." I don't think (D) is necessary, as what the original argument says is that it would be "an incredible waste of resources to burn huge amounts of trash in incinerators" [incinerators in the abstract, not "any" incinerator]. Also, (D) seems to me to miss the crucial part of the argument which mentions the effect of building an incinerator on recycling. In this sense (A) seems more appropriate.

I would appreciate any insights on this!

[maryadkins]

I thought the word "any" made answer (D) too extreme, especially because the question asks for an answer that allows the argument to be "properly inferred." I don't think (D) is necessary, as what the original argument says is that it would be "an incredible waste of resources to burn huge amounts of trash in incinerators" [incinerators in the abstract, not "any" incinerator]. Also, (D) seems to me to miss the crucial part of the argument which mentions the effect of building an incinerator on recycling. In this sense (A) seems more appropriate.

First off, Inference questions do not require you to use the whole argument...review the Inference chapter of the LR Strategy Guide if you're confused on this. You just want to make an inference supported by ANY part of the stimulus (which may not even be an "argument"). Dmitriy captured nicely why (D) works despite "any" and "an":

The contrapositive of D: If huge amounts of trash are burned, then the city is wasting resources. This is stated in the first sentence of the stimulus. Does that help?

Even if we rephrased this as "If huge amounts of trash are burned IN ANY INCINERATOR," it still matches "...in INCINERATORS" in the first sentence. It is a valid inference.

[roflcoptersoisoi]

We can solve this using logical method or using the core method used by those that rely primarily on intuition, I use both methods depending on the question.

Logic Method:

WR= Waste resources
W = Wrong
BI = Burning trash in incinerators
RT= Recycle Trash
Fewer WR= Fewer resources wasted
IB = Incinerator built

Conditional statements:

1st sentence:
WR --> W
BI --> WR

We can link these two up to create the following logical chain:

BI ---> WR --> W

2nd sentence:

RT --> Fewer WR

3rd sentence

IB --> Fewer TR


(A) ~ RT --> BI, no a valid inference. These two statements cannot be linked
(B) more TR --> ~ WR, again, these statements cannot be linked, get rid of this.
(C) most effective way to conserve trash --> RT. This is pretty self explanatory. I am begrudgingly suppressing my indignation and desire to go an expletive ridden tirade about why this answer choice is wrong.
(D) ~WR --> ~ BI. Correct, this is inferable from the passage, this is the contrapositive of: BI --> WR which is introduced in the first sentence. Remember, contrapositive statements are logically equivalent.
(E) ~ BI --> ~WR, this is the negation of: (BI --> WR), if you're proficiency in logo is not strong, this could be a tempting answer choice.

Core/ non logical method:

(A)We're told that if the incinerator is built that fewer trash will be recycled, but we cannot conclusively say from this statement or any of the others in the stimulus at ALL trash that is not recycled goes into incinerators, perhaps they go into a land fill. Get rid of this
(B) We can infer that if we recycle we can waste less resources but not that we would not waste any if we recycled, this goes too far. Eliminate.
(C) We are not given information about the other ways to conserve resources.
(D) We know that if the city burns trash in the incinerator that it will invariably waste resources. Consequently it follows logically that if it doesn't want to waste resources it cannot burn trash in the incinerators.
(E) Not supported by the text. For inference questions you cannot operate on conjecture or bring in other information. Even if the city does not burn trash there could still be conceivably be other ways they could waste resources.

[aaronwfrank]

We can solve this using logical method or using the core method used by those that rely primarily on intuition, I use both methods depending on the question.

Logic Method:

WR= Waste resources
W = Wrong
BI = Burning trash in incinerators
RT= Recycle Trash
Fewer WR= Fewer resources wasted
IB = Incinerator built

Conditional statements:

1st sentence:
WR --> W
BI --> WR

We can link these two up to create the following logical chain:

BI ---> WR --> W

2nd sentence:

RT --> Fewer WR

3rd sentence

IB --> Fewer TR


(A) ~ RT --> BI, no a valid inference. These two statements cannot be linked
(B) more TR --> ~ WR, again, these statements cannot be linked, get rid of this.
(C) most effective way to conserve trash --> RT. This is pretty self explanatory. I am begrudgingly suppressing my indignation and desire to go an expletive ridden tirade about why this answer choice is wrong.
(D) ~WR --> ~ BI. Correct, this is inferable from the passage, this is the contrapositive of: BI --> WR which is introduced in the first sentence. Remember, contrapositive statements are logically equivalent.
(E) ~ BI --> ~WR, this is the negation of: (BI --> WR), if you're proficiency in logo is not strong, this could be a tempting answer choice.

Core/ non logical method:

(A)We're told that if the incinerator is built that fewer trash will be recycled, but we cannot conclusively say from this statement or any of the others in the stimulus at ALL trash that is not recycled goes into incinerators, perhaps they go into a land fill. Get rid of this
(B) We can infer that if we recycle we can waste less resources but not that we would not waste any if we recycled, this goes too far. Eliminate.
(C) We are not given information about the other ways to conserve resources.
(D) We know that if the city burns trash in the incinerator that it will invariably waste resources. Consequently it follows logically that if it doesn't want to waste resources it cannot burn trash in the incinerators.
(E) Not supported by the text. For inference questions you cannot operate on conjecture or bring in other information. Even if the city does not burn trash there could still be conceivably be other ways they could waste resources.

Is there any way you can define the conditional logic a bit more clearly? I'm having trouble understanding how the necessary/sufficient assumptions are reversed in the construction of the wording.

Edit: I think I figured this one out. Since "to," the sufficient modifier, is in the middle, you have to flip the regular order.