#12 - People who say that Dooney County is flat are

[PeterC123]

Hi,

I thought this one had so many flaws it confused me as to which answer was right.

My take on this argument:

Flaw #1: There could be other types of soil erosion on flat land that would force people to build terraces
Flaw #2: They could be building terraces for another reason, other than soil erosion.
Flaw #3: Farms may not be representative of the entire county, so even if there were terraces on the farms, the overall land is flat.

Are these flaws valid or am I just making them up?

Thank you,

[Kristina Moen]

Hi Peter,

This is an Assumption question, so the correct answer choice will be a statement that is necessary for the argument to work. It seems like your approach is to look for flaws or missing pieces, which is a skill that can help you with many question types. Good! However, if you see many flaws or holes in an argument, you can go on to the answer choices and find out what the test makers gave you. An assumption is simply an unstated premise, and there could be many unstated premises.

Let's take a look a the flaws you identified. First, I will find the conclusion. Here, it's "People who say that Dooney County is flat are clearly wrong" aka "Dooney County is not flat." But can I get to that conclusion with the premises in the stimulus? The author tells us that farmers whose land is flat do not build terraces to prevent erosion. Farms in Dooney County are dotted with terraces (side note: sounds lovely!).

Flaw #1: The premise says that farmers whose land is flat do not build terraces to prevent erosion. So it doesn't matter what type of erosion it is.

Flaw #2: Yes! We know farmers build terraces to prevent erosion. We know there are terraces. That might lead you to think that there must be erosion (and so the land is not flat). But you are correct to spot the possibility that there could be other reasons for the terraces. Which leads to Answer Choice (B). Try negating it: "There are NO terraces on farmland in Dooney County which were build to prevent soil erosion." Which means that the terraces were built for some other reason, and wham! The argument falls apart. And we know from the Assumption Negation Technique that if a negated answer choice causes the argument to fall apart, then that answer choice was necessary and it is the correct answer.

Flaw #3: The premises are all about farmland. Remember that you are looking for an assumption on which this argument relies. Furthermore, the conclusion is about Dooney County as a whole. So if part of it not flat, then it is not flat. This flaw may be valid to bring up in casual conversation (i.e. the way you might say "Iowa is flat" even if you just mean that most of it is flat), but in the LSAT World, language is exact and is taken literally.

I hope this helps.

[sdb606]

I can't seem to eliminate C (I picked B).

A flaw in the argument is that terraces could be built for other purposes besides soil erosion (they look nice/bring in tourist dollars). B eliminates this possibility by saying that the terraces were built to prevent erosion, thus supporting the conclusion.

But negating C, if terraces are not effective at preventing erosion, that would seem to support the argument that they were built for some other purpose besides preventing erosion which would weaken the argument and make it a necessary assumption. One reason I ended up eliminating C is because of the possibility that people build things that are not effective. If it were true that the terraces were not effective at preventing erosion, the author could still say, "True. The terraces are not effective at preventing erosion but people built them anyway to prevent erosion (answer choice B), but the terraces just aren't very good. The builders were uninformed and didn't know any better.

Another attempt to eliminate C was to negate it differently. Terraces in DC have not been shown to be effective. Just because something hasn't been shown to be effective doesn't mean it's not effective. That sounds like misuse of evidence. Ultimately, C tells us nothing about the terraces' effectiveness at preventing soil erosion so it's not substantive enough to be a necessary assumption.

Does all that seem reasonable?

Could C be correct if this were a Weaken question?

[MayaPapaya]

bumping the above post.

do we eliminate C because the terraces found on the farmland may have the vestigial effect of preventing soil erosion? and that was not their main purpose?

[Bob O'Halloran]

Hi sdb606 and MayaPapaya,
Thank you for the question. You have the right idea above. For Answer choice (C), the effectiveness of the terraces doesn't really matter. What matters is the reason they were built. This leads us to answer choice (B) .
Then if we apply Assumption Negation to (B), it directly undermines the premise and in turn the conclusion of the stimulus.
The negation of answer choice (C) doesn't really weaken the argument much, it just would show that the farmers weren't wise in trying to prevent erosion by using terraces.
Let us know if you have any future questions.
Bob

[rm_reykjavik]

Hi! I see why B is a nessecary assumption; however, I cannot seem to rule out answer A. I saw the earlier explanation for why A is incorrect: " The premise says that farmers whose land is flat do not build terraces to prevent erosion. So it doesn't matter what type of erosion it is."

However, we know water erosion isn't a problem. I cannot help but think that if there were other sources of erosion than water on flat land (and that those sources of erosion were a problem) then the following sentence wouldn't be true "Consequently, farmers whose land is flat do not build terraces to prevent erosion."

I understand that in assumption questions, we are trying to support the stimulus. Because it's a second family question, we take all answers to be factual and we question the stimulus. To that end, I don't understand why we can just assume that the "consequently" follows the sentence about water erosion and talk about erosion in general. What if there are different types of erosion that are harmful? Then the farmers might have reasons to build terraces on flat land, and that would fundamentally undermine the argument. Thank you!!

[Amber Thomas]

Hi rm_reykjavic!

Let's break down our stimulus.

Premise 1: On flat land, soil erosion by water is not a problem.

Premise 2: As such, farmers whose land is flat do not build terraces to prevent soil erosion (water or otherwise).

Premise 3: Farms in Dooney County are dotted with terraces.

Conclusion: Dooney County is not flat.

So, according to our stimulus, we can determine that since a) there are terraces on farmland in Dooney County, and b) farmers on flat land don't build terraces to prevent erosion, Dooney County is not flat. Too, we know that on flat land, soil erosion by water is not a problem. Since we are calling into question whether or not Dooney County is actually flat, we don't actually know whether or not soil erosion by water is a problem here.

The reason Answer Choice B works is because we know that terraces CAN be built in order to prevent soil erosion of any type, however, we do not know if that is the ONLY reason terraces would be built on farmland. So, in order to properly draw our conclusion that Dooney County is not, in fact, flat, we need to rule out any other potential reasons for terraces to be built. It doesn't actually matter what type of erosion the terraces would hypothetically be built to prevent. Sure, we know that water erosion isn't an issue on flat land, but that could potentially be true for any other type of erosion as well. We just don't know, and it ultimately isn't necessary for our argument to logically follow.

I hope this helps!