Q17 - Selena: Asteroid impact on the Earth caused the extin

[SchneiderME01]

This question has me stumped...

First...I'm not sure if this is an identify the disagreement question because there are two people whose statements we need to read in order to understand the arguement or if this is an assumption question since the question stem says "Trent's argument assumes that"

If I'm understanding this correctly

Selena says

Vast clouds of dust
blocking the suns rays

+ ----> Astroid impact on the earth caused
the extinction of dinosaurs
Asteroid impact at approx.
the right time and a huge
crater in Mexico

Trent says

Asteroid crater is not large
enough

+ ----> The extinctions must have been due
not to asteroid impact on the earth
but to some other kind of cause
Extinction of dinosaurs
took many years

Answer Choices: Honstly I'm not sure how to analyze these I answered D but I couldn't tell you why I ruled the other answer choices out or what made D seem like the best answer choice to me even though it was wrong...a little help please

[timmydoeslsat]

This is a necessary assumption question for the argument that Trent makes.

If this question stem asked for the necessary assumption of Selena's argument, then I would not have read Trent's response. However, with Selena's argument preceding Trent's argument, I believe it is wise to see what Trent is responding to in his argument.

Selena's argument is that asteroid impact caused the extinction of the dinosaurs. She says that there is a big crater and worldwide dust layer to evince this claim.

Trent responds by saying that the crater Selena cites is not large enough for the required amount of dust to produce such a worldwide feat.

He claims that asteroid impact did not cause the extinction of dinosaurs but rather some other cause.

We know that Trent must be assuming that there was not more than one large asteroid that struck earth during the time period dinosaurs were becoming extinct.

If we negated this and said that there was more than one large asteroid, then this brings his conclusion into jeopardy. How would he be able to conclude that it was not asteroid impact that caused the extinction of the dinosaurs?

[maryadkins]

This is a necessary assumption question for the argument that Trent makes.

Yes! Just because you have 2 speakers doesn't necessarily mean it's an Identify the Disagreement question.

We know that Trent must be assuming that there was not more than one large asteroid that struck earth during the time period dinosaurs were becoming extinct.

If we negated this and said that there was more than one large asteroid, then this brings his conclusion into jeopardy. How would he be able to conclude that it was not asteroid impact that caused the extinction of the dinosaurs?

Yes, again!

(A) isn't necessary for Trent to assume. We're just talking about one crater, which is on land.

(B) is not an assumption he makes. His point is about the dust made by the impact of the one asteroid. And if we negate the answer choice to say the dinosaurs in the vicinity didn't survive either, does that destroy his argument? Not necessarily. There could be dinosaurs outside the neighborhood who did survive, i.e. the dinos didn't go extinct.

(C) is too extreme to be a necessary assumption--"any event"?

(D) Trent doesn't address the effects of the dust. He just says the asteroid impact wasn't enough to make the dust.

(E) is correct.

[Yourchoice]

^ What is the purpose of the premise where Trent says that the extinction of dinosaurs took many years; not just one or two? Is it just to throw the reader off? Or just useless information? Both?

I reasoned that (E) could not be the answer because Trent is implying that the one asteroid (if in fact caused the claimed "extinction") it would have killed them within one or two years. But it didn't! It took many years for them to be extinct. If you add another asteroid into the equation, that would mean the dinosaurs would have become extinct even quicker... Which doesn't make sense. Why would he be assuming something that would weaken his argument ?

[maryadkins]

What is the purpose of the premise where Trent says that the extinction of dinosaurs took many years; not just one or two?

It's essentially another premise of his argument:

that particular asteroid crater isn't big enough

+

took longer than 1-2 years

-->

extinction had different cause

An assumption here is also that if extinction takes longer than 1-2 years, it can't be due to asteroid impact. That's a gap between the second premise and the conclusion. But there's also the gap between the first premise (that THAT particular crater wasn't big enough) and the conclusion. Which (E) gives us.

He's assuming there was not more than one asteroid that struck earth during the period when they were becoming extinct, because his argument is based on the one, single crater. This assumption isn't inconsistent with his argument that extinction taking longer than 1-2 years means it wasn't asteroids.

[WaltGrace1983]

I got this one wrong, narrowing it down to (B) and (D) but ultimately choosing (B). I'll explain what I did - the good, the bad, the ugly.

This is a necessary assumption question involving a discussion between two different people. Since Trent, the arguer that we are evaluating in this question, gives a response to Selena it is important to read both of their arguments. I have realized that sometimes there are little language cues that can help you evaluate opposing arguments when you read both of them. Here is what the argument looks like:

Selena
Asteroid impact caused dust, blockage of Sun's rays, and cooling
→
Asteroid impact caused the extinction of dinosaurs

Trent
That asteroid crater is not large enough

→
Extinctions must have been caused by something else

So let's evaluate what Trent is saying. He is saying that the asteroid crater isn't large enough; in other words, he doesn't think that the asteroid was big enough to completely wipe out the extinctions. In addition, he adds that extinctions took place over many years, shedding doubt that this one giant asteroid impact which happens in one instant would be severe enough to cause an entire population of dinosaurs to die out. He has a point here but what is the flaw in the argument?

Well it is tough to see. In fact, this was a question in which I had to go into the answer choices with just a really good understanding of the argument itself, but a limited understanding of the flaw. My initial thought was that Trent is assuming that this particular asteroid did not raise a whole chain of events that, over the course of time, would cause mass extinction. Maybe the asteroid hit and dust scattered, killing off a huge population of the dinosaurs main source of food. This shortage caused an uproar (no pun intended) and the dinosaurs started fighting each other off, etc. etc. etc. you get the point. I thought the answer would look something like this so I went into the choices with these theories in mind.

(A) Definitely not necessary to the argument. Look at this language: any collision. This includes collisions then , now, and of all shapes and sizes. Does this need to be true? No it doesn't. There could be at least one collision that occurs in the ocean. This doesn't change too much.

(C) Similarly to (A), we get this language of any event. Whoa. This includes all events, ever. This is way too strong and is definitely not necessary.

(D) Once again we get this language of any. Is it necessary that this impact would not have had any cooling effect? Maybe it cooled the climate 0.01 degrees Fahrenheit. The purpose of the argument is that it cooled the planet "beyond the capacity of the dinosaurs." Thus, it could have had some cooling effect - Trent is just assuming that this particular cooling effect from this particular asteroid wasn't sufficient to kill of f the entire dinosaur population.

I only have my analysis for (B) and (E) left. I wasn't very confident with my selection of (B) during drilling. During review I changed it to (E). When my review was over I changed it back to (B). I knew that there was something I was missing. Here is what I missing...

That asteroid crater is not large enough


So why is this word that so important here? It is important because Trent is basing his entire argument off of that asteroid not being sufficient. Read the argument again, you'll see what I mean. Now let's talk about the negation test here. If we negate (E), does it completely destroy Trent's conclusion? Not at all! Maybe another large asteroid struck in the middle of the Pacific Ocean and had no effect on the dinosaurs. Who knows, right? However, this is not what the negation test is supposed to do and this is where I got tripped up. The negation test is meant to destabilize the link between the premise and the conclusion. Because I missed the word that, signaling that Trent is only talking about this one asteroid, it made me choose the wrong answer. Let's look at this negation with the argument attached...

That asteroid crater is not large enough
+
There was more than one large asteroid that struck Earth during the dinosaur extinction period.
→
Extinctions must have been caused by something else

All of a sudden, his argument doesn't follow. The negated answer choice is saying that, "hey there was another asteroid impact!!!" but Trent is just focusing on this one asteroid impact. When we add this other asteroid impact in there, his conclusion doesn't logically follow from the premises. That is why (E) is right.

(B) is wrong. I chose (B) because it seemed like the best possible answer and I was just hoping that I was missing something important that made me feel better about (B). Turns out, I was missing something important ! Anyway, (B) is wrong because we are talking about the dinosaurs as a whole - the whole population in the entire world. (B) only discusses the dinosaurs within the "neighborhood" of the asteroid impact, saying that such dinosaurs would have survived. However, all of these dinosaurs in the "neighborhood" could have died while the rest of the species remained intact.

I also want to add an important note about these arguments. Once you read Selena's argument, more or less ignore it. It is great to develop the fullest context for which Trent's argument is based. That is why I read Selena's argument to begin with. However, notice how Trent doesn't talk about "dust" or "cooling" or any of that stuff that Selena talks about. These key words that Selena uses and Trent doesn't will not be in a correct answer. We are all about Trent here, not Selena. See what she is saying, understand how these two arguments fit together, but only focus on what Trent is saying.

Hope that (long) analysis helps someone!