#21 - A study of 30 years of weather pattern records of

[Administrator]

Complete Question Explanation

Assumption, CE. The correct answer choice is (E).

This is a causal argument, and let's look at the stimulus first.

P: After 30 years of study, weather patterns show that weekend days are cloudier than weekday days.
P: The naturally occuring 7 day cycles are not sufficient to change weather in an observable way
C: Human activity (non-natural) is the cause of large scale weather changes.

The author describes a 7-day cycle weather event, namely weekend cloudiness. It gets cloudy at the same time each week, thus that pattern/cycle is 7 days long. Then the author says it’s humans causing that weekly event, because 7-day cycles that occur in nature can’t cause measurable weather patterns. In other words, the author thinks the cause is unnatural (people) solely based on looking at 7-day cycle causes and saying natural ones can't be behind those clouds...but what if some other natural event without 7-day cycles was the cause? What if the cause is, say, twice-daily, or monthly, or annual? Then it could still be natural (non-human) and lead to a 7-day event, such as the one described.

So the author is assuming a 7-day event must have a 7-day cause, and it’s natural 7-day causes the author then rules out as ineffective, essentially. Thus it defaults to humans.


Answer choice (A): We don't need to know that industrial activity decreases on weekends. It could be that driving decreases. Or some other reason that the weekend is different than the weekdays. It doesn't have to be specifically industrial activity decreasing.

Answer choice (B): We don't have to know there are no naturally occurring 7 day cycles, because they've already addressed that any naturally occurring cycles would be too minor to matter.

Answer choice (C): We don't need to know that all impacts living animals can have are due partially to humans. Other changes could be related to other causes.

Answer choice (D): This also doesn't have to be true. For example, at some point in Earth's history, an asteroid likely caused large scale weather changes, but wasn't cyclical in nature at all.

Answer choice (E): This is the correct answer. When we look at (E), it eliminates the possibility that the 7-day event can have a different type of (different cycle) natural cause: any 7-day event (like weekend clouds) with a natural cause must have a 7-day cycle natural cause...i.e. it can’t be monthly, or annually, etc. And since we’ve ruled out a 7-day cycle natural cause already in the stimulus—it's not effective enough—then this 7-day event must be caused by something not natural (like people).

The negation of (E) works pretty well here too: a 7-day event (those clouds) can be caused by natural forces with any type of cycle or time length. Well if that were true, then who cares about a 7-day cycle cause and how ineffective they are...this weekend cloudiness could have been caused by some other natural thing that the author hasn’t considered, and suddenly the argument is in trouble. "It isn't people, it's 28-day lunar cycles." "It isn't people, it's twice-daily tidal flow." And so on.


Put another way, I see it as the author saying "Hey look at that 7-day thing that’s happening. It’s either caused by humans or a 7-day natural cause, but it can’t be the natural cause because 7-day natural causes are insignificant. Guess it's people!" Someone might ask, "Well what about shorter or longer natural causes that could’ve led to it?" And the author’s like (E) "Oh no, any 7-day thing/event with a natural cause has to have a 7-day natural cause, not something shorter or longer like you’re suggesting. And those length natural causes never lead to measurable outcomes like those clouds we're talking about. So my guess is humans."

[eg_m]

Basically I don't understand anything. The stim is so confusing.

We get:
P1: We discovered that weekend days are cloudier than weekdays
P2: the few 7 day cycles that occur naturally are too insignificant to cause measurable weather patterns

C1: Human activity has a measurable effect on weather.

I just don't see any good answers here. Initially A looked good because the question never really defines what cycles are, it just suddenly says "the few 7-days cycle that occur naturally..". Does that mean... 7 days where factories arent producing and "nature" could control weather? I mean, it seems to assume we are working on a 7 day cycle from the get-go, then says the few ones that occur naturally aren't significant. Well wtf are the ones that are not natural? How do you distinguish natural from not natural. It doesn't define anything and it is so frustrating.

It's driving me crazy. It seems like it's saying: Yep, the weather is on a 7 day cycle (5 working days, 2 weekend days, repeating cycle). Also, yup, when a 7 day cycle occurs (naturally? wtf does that mean?), then it's insignificant.

Then the correct answer comes in with "If a weather pattern with a natural cause has a 7 day cycle" (okay, still confused what is the difference between the 7 days natural vs normal/not-natural), "then that cause has a 7 day cycle". We literally know nothing about the natural 7 day cycle. All we know is that for some reason the idea of weekend days having different weather=human cause, and we should operate with the assumption that these human/normal 7 day cycles are not the "natural" ones, because it goes on to say that the natural ones are insignificant. So how E be required for this argument to work. We are saying "those few cycles that don't matter, well they have the have a certain cause otherwise all of the other cycles can't be caused by humans".

I. Just. Don't like this question.

[Rachael Wilkenfeld]

Hi eg_m,

I can see where you got turned around here. Let's look at the stimulus first.

P: After 30 years of study, weather patterns show that weekend days are cloudier than weekday days.
P: The naturally occuring 7 day cycles are not sufficient to change weather in an observable way
C: Human activity (non-natural) is the cause of large scale weather changes.

This is a causal argument. The idea is that human activity CAUSES the weather changes described in the stimulus. The stimulus does a good job of ruling out an alternate cause (natural causes) for the weather changes, but that doesn't mean there aren't still assumptions required for the argument. Causal arguments are inherently pretty weak. Anything that eliminates an alternate cause is an assumption for example.

Answer choice (A): We don't need to know that industrial activity decreases on weekends. It could be that driving decreases. Or some other reason that the weekend is different than the weekdays. It doesn't have to be specifically industrial activity decreasing.

Answer choice (B): We don't have to know there are no naturally occuring 7 day cycles, because they've already addressed that any naturally occurring cycles would be too minor to matter.

Answer choice (C): We don't need to know that all impacts living animals can have are due partially to humans. Other changes could be related to other causes.

Answer choice (D): This also doesn't have to be true. For example, at some point in Earth's history, an asteroid likely caused large scale weather changes, but wasn't cyclical in nature at all.

Answer choice (E): This is the correct answer. It's saying that if a weather pattern with a natural cause would have a 7 day cycle, then that cause would have a 7 day cycle. This means since we've ruled out all the 7 day natural causes, we can rule out all the natural causes. Our stimulus was only ruling out 7 day natural causes. But this says if we see a 7 day natural pattern, the natural cause would have to be a 7 day cycle as well. Since the 7 day cycles can be eliminated per the stimulus, this eliminates ALL the natural causes from consideration. Our conclusion (that it was caused by human activity) requires that all natural causes be eliminated. So answer choice (E) is required for the argument.

Hope that helps!
Rachael

[stu(dying)]

I got this question wrong because I didn't fully understand what the stimulus meant by the seven-day cycles part.

I rephrased this stimulus in my head as, "Human activity has an effect on weather because the seven-day cycles that occur naturally are not significant enough to make a difference on weather patterns".

I thought the gap was between human activity and the weather patterns - the sort of questions that were running through my mind were: what if human activity did not have measurable effects on weather patterns? what if there is alternative reason for these weather patterns? etc.

Is (e) correct because the author in the stimulus is assuming that since the seven-day cycles that occur naturally are not significant enough, then all natural causes of seven-day cycles are not significant enough? If this was not true, then this would open up the possibility that there are some natural causes that could cause measurable effects on weather patterns?

[Zach Foreman]

Dear stu,
Put yourself in the place of this researcher. You notice a pretty strong weekly pattern in the weather, which is pretty weird since why would weather, something natural, follow an artificially created cycle like 7 days? Annual, even lunar, makes sense but how could cloud coverage consistently follow a 7-day pattern? Well, we must uncover the cause of the clouds. The cause is either natural or artificial. We can eliminate the natural causes, apparently, because no natural causes that are significant occur on a 7-day cycle. I prephrased something like car exhaust or factory emissions somehow reduced cloud cover during the week. There are many, many more possible causes that are artificial on a 7-day cycle that could be significant.
But there is an assumption that we are making, one that is so natural that I didn't even really think about it until the answer choice brought it up. Why couldn't the cause be on a different cycle? That would make it much harder to find the cause. It could be geysers on a 3-day cycle or the moon on a 28-day cycle.
The key to cracking any assumption question is to check it with the Assumption Negation Technique. "If a weather pattern with a natural cause has a seven-day cycle, then that cause does not necessarily has a seven-day cycle." If we make that change, we can see that the argument's conclusion is severely weakened because we just dismissed any 7-day cycles as to insignificant, not every natural cycle.

[Jon Denning]

Probably the toughest LR question on the test, and if student feedback is anything to go on possibly of the year thus far. So anyone struggling with it know you're not alone!

Let me see if I can help by briefly outlining my take on it, and how I arrived at the right answer


The author describes a 7-day cycle weather event, namely weekend cloudiness. It gets cloudy at the same time each week, thus that pattern/cycle is 7 days long. Then the author says it’s humans causing that weekly event, because 7-day cycles that occur in nature can’t cause measurable weather patterns. In other words, the author thinks the cause is unnatural (people) solely based on looking at 7-day cycle causes and saying natural ones can't be behind those clouds...but what if some other natural event without 7-day cycles was the cause? What if the cause is, say, twice-daily, or monthly, or annual? Then it could still be natural (non-human) and lead to a 7-day event, such as the one described.

So the author is assuming a 7-day event must have a 7-day cause, and it’s natural 7-day causes the author then rules out as ineffective, essentially. Thus it defaults to humans.

So when we look at (E), it eliminates the possibility that the 7-day event can have a different type of (different cycle) natural cause: any 7-day event (like weekend clouds) with a natural cause must have a 7-day cycle natural cause...i.e. it can’t be monthly, or annually, etc. And since we’ve ruled out a 7-day cycle natural cause already in the stimulus—it's not effective enough—then this 7-day event must be caused by something not natural (like people).

The negation of (E) works pretty well here too: a 7-day event (those clouds) can be caused by natural forces with any type of cycle or time length. Well if that were true, then who cares about a 7-day cycle cause and how ineffective they are...this weekend cloudiness could have been caused by some other natural thing that the author hasn’t considered, and suddenly the argument is in trouble. "It isn't people, it's 28-day lunar cycles." "It isn't people, it's twice-daily tidal flow." And so on.


Put another way, I see it as the author saying "Hey look at that 7-day thing that’s happening. It’s either caused by humans or a 7-day natural cause, but it can’t be the natural cause because 7-day natural causes are insignificant. Guess it's people!" Someone might ask, "Well what about shorter or longer natural causes that could’ve led to it?" And the author’s like (E) "Oh no, any 7-day thing/event with a natural cause has to have a 7-day natural cause, not something shorter or longer like you’re suggesting. And those length natural causes never lead to measurable outcomes like those clouds we're talking about. So my guess is humans."


I don’t know if that helps, but I thought for everyone's collective sanity I’d give it a shot

[stu(dying)]

Omg, I definitely missed the mark. Thanks guys! That was tremendously helpful!

[dbrowning]

I definitely see why E is correct here, but there are two distinct ways to interpret C, one of which makes it a necessary assumption. You could take 'if living organisms' to mean either (a) any particular living organism out of the set of living organisms or (b) the entire set of living organisms. If you interpret the statement as (b), which I think is a reasonable interpretation, C becomes necessary. You essentially get: if the set of living organisms have an appreciable large-scale effect on weather patterns, then this effect is at least partly due to human activity. If we were to negate this assumption, we would get: the set of living organisms (which obviously includes humans) have an appreciable large-scale effect on weather patterns and this is not even partly due to human activity. Because the set of living organisms includes humans, this assumption negated asserts that humans can have no appreciable large-scale effect on weather patterns. This wrecks our argument.

Ultimately, this comes down to whether 'if living organisms' can reasonably be interpreted as the entire set of living organisms, but I think such an interpretation is reasonable. For instance, if we said: 'if bees contribute to a healthier environment...', this could reasonably apply to the entire set of bees, as well as any particular bee.

I would love to hear some feedback on this, as it is why I ultimately chose C over E under timed conditions.

[Adam Tyson]

There's a bit of a problem with your negation of answer C here, dbrowning. Negating an answer means saying that the answer is not true. When negating a conditional statement like this one, you need to say "no, this thing is NOT sufficient for that thing." In this case, a correct negation would be along the lines of "if living organisms have an appreciable large-scale effect on weather patterns, human activity would not have to be a partial cause of that effect."

Don't negate a conditional by saying the opposite of the necessary condition must occur, or that the necessary condition cannot occur. Negate it by saying the alleged necessary condition isn't actually necessary!

Answer C is not required by the argument because the author has indicated that there are no natural 7-day cycles out there. Whatever the other living organisms out there are doing - sharks, llamas, starlings, bacteria, etc. - it would be considered natural, and would therefore not have a 7-day cycle. Instead, focus on the "unnatural" 7-day cycle of the human-created calendar, which revolves around 7 days of the week.

The negation of E is along the lines of "if a weather pattern has a 7-day cycle, it doesn't have to be caused by something else that has a 7-day cycle." If that is true, then there is no longer any convincing evidence that the 7-day cycle we see in the weather must be caused by human activity. It could be something natural!

[lathlee]

Dave,

I hope you consider to put this question as one of hardest LR Question of all time list by Powerscore opinion.