Q17 - A year ago the government

[ocho34]

I thought the flaw in this stiumulus was positing a cause and effect relationship (when it may be a correlation) in the conclusion: that speed limit reduction caused fewer fatalities (ie author is assuming reduction is the only cause of fewer fatalities).

So I am thinking that the correct answer would eliminate any alternate causes.
But I am not sure as to why choice (E) is correct.

[ManhattanPrepLSAT1]

Let's look at the question stem carefully. It says that "The argument is vulnerable to the criticism (flawed) that it takes for granted that"

This is telling us that the argument is taking something for granted (assuming something to be true) and we need to figure out what the argument is assuming. If you treat this question as an assumption question (which it is) you would end up using the negation technique to double check answer choices.

If you negate answer choice (E) it would read "the number of traffic fatalities the year before the new speed limit was introduced was abnormally high". If that were true, the argument couldn't claim that the fewer fatalities was the result of the reduced highway speed limit because it could have been the result of the fatality rate returning to normal. Another way of putting it is that the negation of answer choice (E) provides an alternative cause to the one proposed in the conclusion, which would undermine the argument.

So in the end, you were correct in seeing this argument from a causal perspective. The issue came about in understanding how the question stem mixed up what you were looking for in the answer choices.

[jenndg100380]

Why couldn't it be B. then? B. could also introduce an alternative explanation...The argument does take for granted that the drivers obeyed the speed limit. If the drivers didn't obey the speed limit, then the reduction in fatalities would be due to another reason.

Is it because E. is just a better answer since it actually gives you an alternative reason?

[ManhattanPrepLSAT1]

I completely agree that answer choice (B) is very tempting. I think as you spend more and more time in the head of the LSAT writer you're going to be very cautious about choosing an answer choice like (B). The reason is a common one. On necessary assumptions, it is common that answer choices that say something like:

Most professors are lecturers.
or
The majority of bicyclists are in excellent cardiovascular condition.

In this case, it doesn't need to be assumed that the majority of drivers obeyed the new speed limit, but rather that at least some drivers obeyed the new speed limit.

What's so magical about hitting the 51% mark? Wouldn't 49% of drivers obeying the speed limit be sufficient to potentially significantly reduce traffic fatalities?

Does that help clear this up? I can see this is a tough one. This has direct relevance to other necessary assumption questions, so it's important that you see this distinction between "most" and "at least some" and know that on necessary assumptions, the argument would have to be very carefully constructed to require an assumption about the majority of any particular group.

[adarsh.murthy]

Hey TimmydoesLsat,

you have been answering lot of my posts, so thanks for that! I think it a great catch about the term shift in C!

I was wondering what the word CAN in the conclusion could mean!? isnt can just ruling out the causality between speed limit and accidents? If this is true, it would also mean C is wrong, right?

Thanks!

[timmydoeslsat]

I will be glad to help with all of your questions!

The word "can" in the conclusion is a great find by you. We want to think about what it means in this instance.

To start, we need to think about what this argument did.

It gave us a premise:

- A year ago, the govt reduced the highway speed limit.

- In the year since that time, there have been fewer highway fatalities than in the previous year.

From those two premises given to us as evidence, the author concludes that speed limit reduction "CAN" reduce traffic fatalities.

The author is concluding cause. The stimulus gave us a correlation.

Just because event A happened (the govt reducing the speed limit)...does not mean that IT CAUSED event B to happen (highway fatalities was lower than last year).

It could be a different cause, such as a new hospital that was built in a highly traveled area of a highway, which gave motorists a better chance of not being a fatality in the event of an accident. Or maybe last year's accident numbers were just unusually high. (Which is the alternative cause that the LSAT chose here)

2007----2008----2009----2010
--7-------9-------50-------7--
-------------------X*---------

X* = Govt introduced speed limit reduction

So by having a situation where, in 2009 for example, the highway fatality total was much higher than the other years in this set, makes you less certain that it was, in fact, X* that caused the low number.

The possibility of there being a ridiculously high fatality total really throws a wrench into things! This argument is flawed because it takes for granted (another way to state assuming) that this idea did not take place! And as it stands now, it most certainly could!

So the phrase "can reduce" in the conclusion is telling us that the speed limit reduction caused this event of the lower fatalities.

[ymcho2013]

What about answer choice D?

If you negate the answer choice: the speed limit was NOT more strictly enforced (meaning that it was either equally enforced or less enforced) than the old...

then wouldn't this break down the argument that reducing speed limits reduces fatalities? because if it was equally/less enforced, then it cant be that the speed limit reduction cause the fatalities to decrease....

any help would be appreciated!

[timmydoeslsat]

Lets go back to what we know from this stimulus.

We have a flaw question stem of the variety that indicates a flaw in which the argument takes for granted that...in other words, the argument is flawed due to it assuming which one of the following 5 answer choices.

We know that this argument is jumping from a correlation to a cause.

Does the argument assume that this new speed limit was more strictly enforced than the old one? No. Even if you negate it, you will see that it could have been enforced as strictly. This is just a time-wasting answer choice. It will help you think about what assumptions are necessarily made when you jump to cause.

Think about what the argument does assume when it jumps from the correlation to the cause. It assumes that nothing else was responsible for the occurrence. Couldn't there have been a government ad campaign that promoted people to buckle up their seat belts? Perhaps that is what caused it.

The test writers to chose a rare way to attack causation, which is to say that there was simply a rather unusual large occurrence of fatalities the year prior and that current year is simply showing the normal rate.

[zaidjawed]

Hey Guys,
Why couldn't A) stand out as an assumption too? I was stuck between A) and E) and decided to go with A). My reasoning, once again, was that another cause such as increased highway traffic led to people driving slower and hence reduced traffic fatalities" .

E) absolutely made absolute sense when i read timmydoeslsat's post, however, I want to understand why A) is incorrect.

Is A) incorrect because I looked at it as highway traffic reducing traffic fatalities by causing people to slow down when in fact it could act as a means to increase fatalities? In reality, I could see either effect of A) as being plausible.

If this is the case, I will often find it hard to rely on my own knowledge of things when in fact some of the answer choices rely on my ability to make inferences by common sense standards.

Any thoughts, people?

[ManhattanPrepLSAT1]

Lets walk through this one from the beginning. The argument concludes that speed limit reduction can reduce traffic fatalities (notice the causation implied!). Why? Because the government reduced the highway speedlimit and in the year since, there were fewer highway traffic fatalities.

The argument is flawed in that it mistakes a correlation between two events for a causal one. The argument took for granted that something else did not cause the reduction in the number of traffic fatalities.

Answer choice (E) eliminates a possible alternative explanation for why there was a reduction in the number of highway traffic fatalities. The argument must assume that some other explanation is not correct in order to conclude that the offered explanation is correct.

Incorrect Answers
(A) states the opposite of what it should. Increasing highway traffic would increase the risk of traffic accidents. This answer should have stated that the argument took for granted that highway traffic has not decreased. If traffic had decreased, that could provide an alternative explanation for the reduction in highway traffic fatalities).
(B) need not be true. The reduced highway speed limit could have reduced highway fatalities even if only some people had obeyed the new speed limit.
(C) need not be assumed. Why do we need to assume any connection between the speed limit and the number of accidents? Couldn't it be the case that the reduced highway speed doesn't reduce the number of accidents, but it does reduce the severity of those accidents so that more people survive them.
(D) need not be assumed. The new speed limit could have been equally enforced as the old speed limit and yet the new speed limit could still have reduced the number of highway traffic fatalities.

[magnusgan]

Hey Matt, does the possibility of causation imply causation?

Just because something can cause something else doesn't mean that it does...

That medicine can cause drowsiness doesn't mean that medicine always causes drowsiness; it just has the potential to cause drowsiness.

What I'm trying to get at is that there is no correlation to causation flaw in this argument. Rather, the person making the argument is jumping to conclusions, or making an unsupported inference.

What do you think?

[rickytucker]

Hey Matt, does the possibility of causation imply causation?

Just because something can cause something else doesn't mean that it does...

That medicine can cause drowsiness doesn't mean that medicine always causes drowsiness; it just has the potential to cause drowsiness.

What I'm trying to get at is that there is no correlation to causation flaw in this argument. Rather, the person making the argument is jumping to conclusions, or making an unsupported inference.

What do you think?

There was another post in this thread that addressed the "can" issue but I'll rehash it in different terms.

You are correct, the author is merely asserting possibility of a causal relationship which would allow for the possibility of five incorrect answer choices. However, as smart LSAT takers we know with 100% certainty that there is one correct answer choice and four incorrect answer choices. Therefore, as smart LSAT takers we must infer that the writers of this question are asserting an absolute causal relationship, not mere possibility.

[wonderwoman]

I ran into a problem on this question that I suppose is silly, but I wonder if anyone has any suggestions about it regardless.

When I saw the phrasing "abnormally high," I just interpreted that to mean that the number of highway fatalities in that area were abnormally high compared to other areas, which I felt was irrelevant to the argument. If this area just had an unusually high rate of highway fatalities, I reasoned it would make sense that the government would try to reduce that rate somehow, and that they may have some success in doing this.

I understand now that by "abnormally high" they meant that the rate of highway fatalities was higher in that past year than was ordinary for that area, which would mean that there was an alternate explanation for the reduction in traffic fatalities for this year.



I guess my question is: is there something in the stimulus or in the answer choice that would make my interpretation of "abnormally high" wrong? I feel like I miss a lot of questions but just misinterpreting language in a way that isn't technically incorrect, it just leads me to eliminate the correct answer and I'm not sure what I can do to fix this.

[Aquamarine]

I kept reading the explanation above, but I still have no idea why A is wrong.

Why A can't be an answer? Does highway traffic "has not increased" mean highway traffic is the same as a year ago?
So I think A also eliminates a possible alternative explanation for why there's a reduction in the number of highway traffic fatalities.

Can anyone explain why A is wrong and E is an answer?
Thanks!

[mr13n]

I still do not understand how E is right. So what if the number of fatalities the year before the new speed limit was enforced was NOT really high? Even if 3 people died the year before, and we follow the stimulus in that it says "there have been fewer fatalities than in the previous year (let say 2 people)," it wouldn't be wrong to conclude that this speed limit reduction did in fact reduce fatalities. There was in fact a reduction, is the word "significant" the problem? Cause that would just leave it up to interpretation, one life saved is significant to me.

[ohthatpatrick]

PHENOMENON: This year, significantly fewer highway fatalities than last year

AUTHOR'S EXPLANATION: The speed limit reduction led to the fewer fatalities

===========

There are two pressure points for an LSAT explanation:
1. Plausibility of the Author's Explanation
2. Alternative explanations for the same evidence

(C) was almost a #1. Had it said "the author assumes a relation between speed limit and the number of highway fatalities", it would be correct.

The more common direction for LSAT to go is consider alternative explanations for the same evidence.

Why ELSE could it be that were there fewer highway fatalities this year, compared to last year?

If we negated (A), it would say "highway traffic has increased". Is that an alternative explanation for "fewer fatalities"?

Doesn't sound very common sense to me. If anything, I would think that more traffic last year would lead to MORE, not fewer, fatalities.

So negating (A) does not turn into an objection.

Negating (E) turns into an alternate explanation.

Last year's highway fatality figure was abnormally high, so even if we had done nothing with speed limits, we would have expected this year's number to be lower.

One night, Kobe Bryant scored 81 points in a basketball game (though his average is about 30 points per game). If he scored 30 points the following night, we could say that he scored fewer points than he did the previous game.

Say he wore a new pair of shoes for the 30 point game. Would we say, "Ah, clearly wearing a new pair of shoes can decrease how many points Kobe scores"?

We could, but we could also just say "the new shoes didn't do anything wrong. This is an average, normal game. It's the 81 point game that needs an explanation. THIS game doesn't need one."

That's the way that (E) is hurting the argument. You wouldn't give new speed limits "causal credit" if the fatality number came back to average.

(In statistics, this is called a natural "regression to the mean")

After an outlier data point, you're going to naturally see subsequent data points that are closer to the average. This drift doesn't need an explanation beyond the law of averages.

[mr13n]

Wow. Perfect explanation. The Kobe analogy really helped. Thank you

[seychelles1718]

I think I got this wrong b/c I used a wrong strategy. I approached this question without knowing it can also be treated as a necessary assumption question, because I thought only Q stems saying "depends," "requires," "must," "relies," etc. indicate necessary assumptions.

So can I ALWAYS treat some questions with phrases such as "takes for granted" and "fails to consider" as necessary assumption questions? Are there any other Q stems that I can recognize and treat them as necessary assumption Qs?

[maryadkins]

Great question!

Here's a rule you're going to love: flaws are necessary assumptions.

When a flaw question asks you what the argument TAKES FOR GRANTED, it is asking for a necessary assumption.

When a flaw question asks you what it FAILS TO CONSIDER, it is asking you for a necessary assumption in a roundabout way. It is asking you what necessary assumption the argument is making that causes it to IGNORE ANOTHER POSSIBILITY.

And if you ever just have a question stem that asks you, "What is the assumption?" or "What does the argument assume?", treat it as a necessary assumption question.

Hope this helps.

[seychelles1718]

Thanks so much, mary!!!