#11 - In the last year, biologists have learned that there

[Administrator]

Complete Question Explanation

Flaw in the Reasoning. The correct answer choice is (E)

This stimulus begins with the fact that over the past year, it has been discovered that there a lot
more species of amphibians than had been thought. The author asserts that this premise weakens the
environmentalist claim that each year, many amphibian species are killed by pollution:

• Premise: Environmentalists claim that many species of amphibians die each year as a
  result of pollution.
  
  Premise: Over the past year, however, scientists have discovered that there are more
  amphibian species in existence that had been previously thought.
  
  Conclusion: Thus, the environmentalist claim is undermined.

The problem with this argument is that one does not preclude the other in any way; regardless of the
big recent discoveries, pollution could certainly be killing many amphibian species each year.
As you might have seen coming, the stimulus in this case is followed by a Flaw question, so the
correct answer choice should describe the misunderstanding reflected in the author’s reasoning.

Answer choice (A): This choice describes confusion between categories and those things that are
categorized. This does not describe the issue with the author’s reasoning, so it should be ruled out of
contention.

Answer choice (B): This choice describes the classic conditional error of Mistaken Reversal—
mistaking a necessary condition for a sufficient one. The stimulus’ flaw, however, is not a conditional
reasoning error, so this cannot be the correct answer choice.

Answer choice (C): The author’s argument is based on a misunderstanding of the numbers,
rather than something to do with cause and effect. Since the argumentation is not based on causal
reasoning, this cannot be the choice that describes the flaw.

Answer choice (D): This choice, like incorrect answer choice (C), describes a causal reasoning flaw.
The author’s argument, however, is not based on causal reasoning, so this choice does not describe
the flaw.

Answer choice (E): This is the correct answer choice. We now know about many more amphibian
species, but clearly that doesn’t mean that the number that exists hasn’t continued to dwindle.

[Sherry001]

Hello,
For this question I was able to get to the correct answer, because it seemed perfect but I couldn't help get tempted by answer choice D. Only because I was totally convinced that there was a causal argument implied by the author.
So looking at the conclusion doesn't this translate to denying pollution as a cause of their extinction?

1- biologists have discovered many more species of amphibians in existence then previously known .

Conclusion : this definitely undermines the claim that pollution is eliminating many of these species every year .


Thank you
Sherry

[David Boyle]

Hello,
For this question I was able to get to the correct answer, because it seemed perfect but I couldn't help get tempted by answer choice D. Only because I was totally convinced that there was a causal argument implied by the author.
So looking at the conclusion doesn't this translate to denying pollution as a cause of their extinction?

1- biologists have discovered many more species of amphibians in existence then previously known .

Conclusion : this definitely undermines the claim that pollution is eliminating many of these species every year .


Thank you
Sherry

Hello Sherry,

There may be some causality implied, so maybe people could argue for answers C or D a little bit. Answer E is the "cleanest" answer, though, since it neatly describes what happens: the first part of the stimulus talks about our knowledge about amphibians, which is not identical to changes in amphibians.

Hope this helps,
David

[starre]

I put A for this question. When I was taking the test, I had it narrowed down to A and E (I determined the stimulus wasn't conditional or causal and eliminated the other answer choices). Neither A or E seemed great to me, and I was a bit confused on the wording for both of them. I picked A because it seemed to make more sense than E. I still don't understand what E is saying and how it corresponds to the stimulus. What are the objects and changes it refers to in the stimulus? Also, I put A because the species of amphibians seemed like kinds of things to me, and you can say what is true for the species is true for all amphibians, which is a part to whole like A implies. Where did I go wrong in my thinking?

Thank you,
Emily

[Clay Cooper]

Hi Emily,

Thanks for your post.

Answer choice E suggests that the author has mistaken a change in our knowledge of something for a change in the thing itself. For instance, E would be accurate if the stimulus had said:

The way black holes work has recently changed; before, we thought that nothing ever escaped them, but new research proves that Hawking radiation does escape them.

In that example, black holes themselves haven't changed, we have just learned more about how they work. The same mistake is made here: the author notes that new evidence indicates that there are apparently many more species of amphibian than we had previously thought. The number of amphibian species in existence has not necessarily increased, but our estimates of the number of amphibian species in existence has increased. Therefore, it does nothing whatsoever to attack the claim that pollution is nonetheless reducing the number of species.

Answer choice A, by contrast, describes a flaw in which the number of a thing is confused for the number of types of that thing. If the author's mistake had been to say that, since we now know there are more amphibian species than we had thought, there must be more amphibians than we had thought, answer choice A would be correct.

Does that clarify it some?

[starre]

Yes, it does! Thank you!

[lathlee]

Hi. I got this question correct. but i would like to know what reasoning error this question contains for the future reference is it use of uncertain terms in broad version?

[Adam Tyson]

That's a good question, lathlee, and not one with an easy answer. Some flaws defy easy categorization, while others could appear to fit into more than one category. My first advice is to not spend any time or energy trying to categorize the flaw, because that is not the goal on this test, Rather, focus on trying to understand the flaw so that you can select an answer that best describes it. Categories may help, if they act as a type of shorthand code that helps you cut to the chase, but trying too hard to categorize a flaw can also hinder you by wasting your time on the wrong task.

I might call this a general lack of relevant evidence, because "how many" tells me nothing about changes in the amount, or because it confuses what we know exists with what actually exists. I could call it a numbers and percentages flaw, because it attempts to use info about a vague numerical concept ("many more") to prove something about relative changes in the total (decreasing). I don't think I would call it an "uncertain term" flaw because I don't see a term being used in more than one way here. If you do, tell us which term and what the two meanings are that you see, as that is the best test to see if that is the right sort of answer to select.

Ultimately, the name of the flaw doesn't matter. What matters is that you understand what's wrong, and can see which answer does the best job of explaining that problem.

Keep at it!

[mo_wan]

Hi,

I am a little confused on the idea that when we discover more of the species, that doesn't mean that there's actually more of that species. I understand that it has no relationship in the fact that there alot of them still being killed but that i am having trouble wraping my head around the flaw

[Adam Tyson]

With Halloween around the corner, allow me to illustrate with candy. We have stocked up on candy in preparation for the big day, but I have a serious sweet tooth and cannot keep my hands off the stuff. I keep eating the candy that we are supposed to be saving for the kids.

My wife, brilliant woman that she is, hid two bags of candy so I wouldn't get into them. Now, as I eat the candy, I start to worry that the total amount of candy is diminishing. We are losing candy at a furious rate! It's disappearing!

At the last minute, my wife pulls out the hidden candy. We're saved! We have more candy than I thought we had! But, we still have less candy than we had before I got greedy and starting gobbling it up, right? That candy is still gone, our total is still lower, even though I am now aware that the total was and is larger than I had previously believed. Just because we have more than I thought we had doesn't mean that I haven't been eating into that total. The only thing that changed was what I knew about that total. My knowledge of the facts changed, but the facts did not.

Happy Halloween, mo_wan!