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ohthatpatrick
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Q18 - In grasslands near the Namib Desert

by ohthatpatrick Sun Oct 28, 2018 7:00 pm

Question Type:
Strengthen

Stimulus Breakdown:
Conclusion: The burrowing of termites caused the fairy circles to form.
Evidence: Termites are found in every fairy circle (large patch of grassland entirely devoid of vegetation) we've investigated.

Answer Anticipation:
CURIOUS FACT: Why do fairy circles exist (and why do we always find sand termite colonies there)?
AUTHOR'S EXPLANATION: The burrowing activities of termites cause them.

We always address causal arguments with the same two pressure points:
"Is there some OTHER WAY to explain the curious fact?" and
"How plausible is the AUTHOR'S WAY of explaining it?"

Since we're strengthening, we need to either rule out some other way of explaining fairy circles or why sand termites are found in fairy circles, or we need to corroborate the author's theory in some fashion.

Correct Answer:
A

Answer Choice Analysis:
(A) YES, surprisingly. Most of us are going to skip this on the first pass, but the fact that the dying plants that give way to a fairy circle are damaged only at the roots suggests that whatever is causing fairy circles is a below-ground phenomenon, not an above-ground phenomenon. Since the author thinks "burrowing activities" cause the circles (and burrowing means to dig underground), this fact adds some plausibility to the AUTHOR's WAY.

(B) This might seem to rule out the idea that fairy circles form because the vegetation simply dies out due to climatic factors (it sounds like vegetation in that area is quite robust). However, ruling out the idea that fairy circles are forming from climatic conditions doesn't take us as close to believing the burrowing-termite hypothesis as (A) does. In general, ruling out some other causal explanation isn't as powerful as bolstering the author's specific hypothesis.

(C) This seems to rule out the idea that fairy circles are formed from a lack of water, not termites. Again, this mildly strengthens by ruling out some other possible explanation, but this would have the same strength as (B). They both lose to the specific burrowing-clue that (A) offers.

(D) This has no clear impact. The fact that fairy circles form near each other doesn't really argue in favor of or against the termite hypothesis.

(E) This corroborates the idea that termites are found near fairy circles, but we already KNOW termites are found near fairy circles, so we don't need to further support THAT idea. We need to assess whether termites are responsible for the fairy circles and this doesn't take us any closer. For all we know, the fairy circles form first, and then termites come second, because they like areas entirely devoid of vegetation for some reason.

Takeaway/Pattern: To me, the challenge of this problem boils down to whether we overgeneralize the conclusion as "the termites are the cause" vs. specifically seeing the author say "the BURROWING ACTIVITIES of the termites are the cause". That subtle choice of wording was not for nothing. If nothing else, we should pause to give (A) some consideration because it is strongly worded, so it might have some punching power. Why would we care about "damaged ONLY at the roots"? Ohhhh, because it relates to digging underground.

#officialexplanation
 
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Re: Q18 - In grasslands near the Namib Desert

by DPCTE4325 Sat Jun 01, 2019 12:04 am

ohthatpatrick Wrote:Question Type:
Strengthen

Stimulus Breakdown:
Conclusion: The burrowing of termites caused the fairy circles to form.
Evidence: Termites are found in every fairy circle (large patch of grassland entirely devoid of vegetation) we've investigated.

Answer Anticipation:
CURIOUS FACT: Why do fairy circles exist (and why do we always find sand termite colonies there)?
AUTHOR'S EXPLANATION: The burrowing activities of termites cause them.

We always address causal arguments with the same two pressure points:
"Is there some OTHER WAY to explain the curious fact?" and
"How plausible is the AUTHOR'S WAY of explaining it?"

Since we're strengthening, we need to either rule out some other way of explaining fairy circles or why sand termites are found in fairy circles, or we need to corroborate the author's theory in some fashion.

Correct Answer:
A

Answer Choice Analysis:
(A) YES, surprisingly. Most of us are going to skip this on the first pass, but the fact that the dying plants that give way to a fairy circle are damaged only at the roots suggests that whatever is causing fairy circles is a below-ground phenomenon, not an above-ground phenomenon. Since the author thinks "burrowing activities" cause the circles (and burrowing means to dig underground), this fact adds some plausibility to the AUTHOR's WAY.

(B) This might seem to rule out the idea that fairy circles form because the vegetation simply dies out due to climatic factors (it sounds like vegetation in that area is quite robust). However, ruling out the idea that fairy circles are forming from climatic conditions doesn't take us as close to believing the burrowing-termite hypothesis as (A) does. In general, ruling out some other causal explanation isn't as powerful as bolstering the author's specific hypothesis.

(C) This seems to rule out the idea that fairy circles are formed from a lack of water, not termites. Again, this mildly strengthens by ruling out some other possible explanation, but this would have the same strength as (B). They both lose to the specific burrowing-clue that (A) offers.

(D) This has no clear impact. The fact that fairy circles form near each other doesn't really argue in favor of or against the termite hypothesis.

(E) This corroborates the idea that termites are found near fairy circles, but we already KNOW termites are found near fairy circles, so we don't need to further support THAT idea. We need to assess whether termites are responsible for the fairy circles and this doesn't take us any closer. For all we know, the fairy circles form first, and then termites come second, because they like areas entirely devoid of vegetation for some reason.

Takeaway/Pattern: To me, the challenge of this problem boils down to whether we overgeneralize the conclusion as "the termites are the cause" vs. specifically seeing the author say "the BURROWING ACTIVITIES of the termites are the cause". That subtle choice of wording was not for nothing. If nothing else, we should pause to give (A) some consideration because it is strongly worded, so it might have some punching power. Why would we care about "damaged ONLY at the roots"? Ohhhh, because it relates to digging underground.

#officialexplanation


Hey Patrick!

I got down to A & B using your method, but I wanted to know whether I could rule out B with the following rationale:

As you noted, I kept B because it seemed to rule out an alternative explanation. But on a closer inspection, I don't actually think it's ruling out an alternative explanation for WHY fairy circles form. B instead talks about grass that grow AROUND fairy circles; so we can still have our fairy circle -- circular patch of nothingness -- and have there still be grass AROUND it (meaning outside the literal circle itself).

Or is B still "ruling out" an alternative explanation since the close proximity of the grass growing "around" the fairy circle is impactful enough such that if the grass surrounding the fairy circles are able to survive harsh weather then so can the stuff inside the fairy circle?

What do you think?
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Re: Q18 - In grasslands near the Namib Desert

by ohthatpatrick Mon Jun 03, 2019 1:54 pm

I think people may have thought to themselves, "What if fairy circles form simply because all the plants in that circular patch have died off? Like maybe a certain type of plant grows in circular patches, and then if it dies off from too much sun / not enough moisture, then it would leave a large circular patch of vegetation."

(B) would kinda push back against that by saying, "really? the nearby vegetation is able to survive harsh, prolonged droughts. It would be weird if, in the same habitat, you had species of grasses that were adapted to harsh, prolonged droughts immediately next to some other plant species that dries up, dies, and disappears from the same conditions."

But this is a STRETCH of an alternate explanation to begin with. We know, commonsensically, that plants do not usually grow in tightly defined circular patches in the wild. So it's pretty weird to suggest that a special plant life WAS living in a circle, amidst these grasslands, and that once that plant life died it left a patch ENTIRELY devoid of vegetation.

Essentially, (B) kinda sounds like it's implying "Harsh and prolonged droughts DID NOT create these fairy circles, since adjacent vegetation was perfectly capable of surviving these harsh and prolonged droughts."

All of that is pretty thin as a strengthener, which is why the more direct corroboration of "damaged only at roots (damaged underground --> damaged by burrowing activities)" would be a much more compelling strengthener even if we COULD straighten out our story for what ONE alternative storyline (B) would be ruling out.