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  Michael.Cinco Member Sage ⭐

  October 2019 edited October 2019 2116 karma

  There is a bit of a gap between the premise and conclusion as there always is on most argument in the lsat.

  P1. In a study 30 years worth of weather patterns in several industrialized urban areas it was found that weekends tended to be cloudier than weekdays

  P2. There are few naturally occurring 7 day cycles, and those that exsist are too insignificant too cause measurable weather patterns.

  Conclusion: Therefore you cannot deny
  That human activity has an appreciable large scale affect on weather

  I can see why you might think C is an attractive answer choice. The idea of 'human activity' only appears in the conclusion and if you were looking for a bridging necessary assumption it's a perfect candidate to try and tackle.

  Unfortunately C kind of goes off the rails by saying that if a living organism caused changes to the weather than humans must have played a role.

  The gap you need to cover is the assumption that if its a non-natural cause then it's human caused. Natural can still encompass things caused by animals which are also living beings so for the purposes of the argument C overreached and is not necessary

  E works because it highlights another big flaw/assumption the argument makes.

  How can you base your conclusion ONLY on the effects of naturally occurring 7 day cycles? Why not a volcanic explosion which can occur in one day? Or a plague of locusts which can occur over a month? The argument is assuming that if a certain weather pattern exsists in a certain cycle (weekly) then the CAUSE of that cycle must also be of equal length. If that link was not there then the argument breaks down because the gulf between p2 and the conclusion is depending on that assumption and that's what E elegantly points out.
• Peaceofmind Alum Member

  October 2019 edited October 2019 446 karma

  @"Michael.Cinco"
  Thank you for your explanation. I’m still confused by this question though.

  I chose C because I thought negating the necessary condition would destroy the conclusion, but I do realize that the sufficient condition doesn’t match the stimulus.
  Also I can’t see why E is right because I thought the stimulus assume if the cause is not natural then the cause is human activity, while E seems to just talk about how the author assumes that natural cause has a seven-day cycle, and seems like it doesn’t address the gap between premise 2 and the conclusion. Is it actually addressing the gap between premise 1 and premise 2 (intermediate conclusion)?

  help
• Michael.Cinco Member Sage ⭐

  October 2019 edited October 2019 2116 karma

  @Peaceofmind said:
  @"Michael.Cinco"
  Thank you for your explanation. I’m still confused by this question though.

  I chose C because I thought negating the necessary condition would destroy the conclusion, but I do realize that the sufficient condition doesn’t match the stimulus.
  Also I can’t see why E is right because I thought the stimulus assume if the cause is not natural then the cause is human activity, while E seems to just talk about how the author assumes that natural cause has a seven-day cycle, and seems like it doesn’t address the gap between premise 2 and the conclusion. Is it actually addressing the gap between premise 1 and premise 2 (intermediate conclusion)?

  help

  Ok so let's clarify how we negate a conditional statement.

  From what you wrote it seems that you are just negating the necessary condition. Which unfortunately is not how you do it. Negating a conditional statement for the purposes of the negation test means saying that the conditinal relationship infact does not exsist!

  Example:

  If A then C

  Negating that statement is

  NOT (IF a then C)

  What does that mean?

  That means A is not sufficient for C and C is not necessary for A. which means A CAN occur without C occurring (A and not C)

  In the context of the question the negation of C is saying that you can have living organisms make appreciable changes to weather patterns without having human involvement

  But the stimulus is talking about Natural Causes vs Non Natural (assumed to be human) causes of weather patterns. They are talking about two related but different things. Natural causes can include living organism (beetles) that aren't human. Living organisms excludes natural causes that are not living like the sun or volcanoes.It's why C is tricky but ultimately incorrect.

  Now let's go to E again.

  The premise says that no natural occurring 7 day cycle can cause weather patterns from that it concludes that since no Natural 7 day cycle causes weather patterns then it must be humans (assumption non natural = human) that caused the weather pattern.

  The key is why are we limiting it to natural 7 day cycles for the cause of the 7 day weather pattern? Why can't it be a 2 day natural cycle or a 5 day natural cycle or a 500 day natural cycle?

  There is another assumption tying the # of days in the CAUSE vs the # days in the Effect (the # of days in the weather pattern)

  Look at what E says:

  If a weather pattern with a natural cause has a 7 day cycle than the CAUSE has a 7 day cycle.

  Let's negate this conditional

  A weather pattern with a natural cause has a 7 day cycle can now have a cause that does not have a 7 day cycle.

  See how that attacks your argument ? The argument is based on the idea that there are no natural 7 day cycles that can cause weather patterns and thus the (weekly/7 day) weather patterns observed must be caused by non natural causes (assumed to be humans) but by negating E the length of the weather pattern is no longer tied to the length of the cause. The 7 day weather pattern can have a Cause with a 2 day cycle or a 5 day cycle.

  Hope that helps
• youbbyun Alum Member

  October 2019 1755 karma

  This is a really tough question. Any other ppl have their explanation?
• lsatslayer-1 Member

  October 2019 113 karma

  Here is my process and explanation. First rephrase it to simple terms: conclusion, human activity have a great large scale effect on weather. Premise: during weekends some industrialized urban areas tend to be cloudier.
  Then it rules out an alternative explanation, the 7 day natural cycle. POE rules out other answers, none is as close as E, although that one is confusing. As said in previous comments, if you negate that,it breaks apart argument: if natural weather pattern does Not have 7 day weather cycle, it has 7 day cycle cause. This goes against the flow of our argument because the premise indicates that is DOES NOT occur in 7 day cycle, it happens during weekends, and it also rules out 7 day weather pattern.

  But if you don’t like negating because it doesn’t always work, remember the negating destroys the support which kills the conclusion rather than the conclusion directly. Also focus on structural reasoning, which in this case, the author ruled out 7 day cycle as an explanation for the strange weather pattern. Does the fact that it occurs it a “few” times rule it out? No it needs additional support!!!
• duncan chiu Alum Member

  March 2020 10 karma

  Got this wrong under timed as I was scanning for bridges. Just goes to show that method doens't always work.

  Got it in BR after coming back a few times and here's my mindset:
  I broke this question done to parts to process easier but what I did was I made the first half of the stimulus the context/phenomenon and the second half our hypothesis. Doing this made it really clear why E is wrong.

  The phenomenon is that weekend days tend to be cloudier. If you used this as premise 1, you'll realize it doesn't really effect our argument other than to set it all up.

  Our hypothesis/conclusion is that humans must have appreciable effects on weather.

  That leaves us only with our only support for this hypothesis...which is "it's not 7-day cycles because those are insignificant".

  If this were a flaw question, the answer would pop out much easier...why are they only looking at 7 day cycles? How can you jump from not 7 day cycles to must be humans? Now of course if an AC said that, this question wouldn't be as tough as it is but of course the LSAT writers went ahead and hid all that in answer choice E.

  If you negate what E says, it says if a weather pattern has a natural cause, it might not be a 7-day cycle (or you can have a natural cause and not a 7-day cycle). That would completely open the gates for the flood of questions I mentioned above. "why not look at 1-day cycles, 2 days? etc. why only 7 day cycles?"

  That is why E is necessary. Because if it must be a 7-day cycle and we know that 7-day cycles are insignificant, then perhaps it is humans who have an effect. Without that assumption, simply looking at 7-day cycles is a massive flaw in the argument.