#17 - Selena: Asteroid impact on the Earth caused the

[chian9010]

Dear Powerscore,


Trent's promise: The extinction of dinosaur species took many years, not just one or two.

Trent's conclusion: So the extinctions must have been due not to asteroid impact on the Earth but to some other kind of cause.

This is an assumption question and I don't understand why E is correct and C is incorrect.
If we negate E ,more than one large asteroid struck the Earth during the period when the dinosaurs were becoming extinct. This doesn't seem to weak the conclusion because all of the asteroid struck could be weak
If we negate C, "any event that takes place over a long period of time doesn't have many different kinds of causes" this directly weaken the conclusion. Doesn't it?

[Brook Miscoski]

Chian,

Trent concludes that something other than asteroids killed the dinosaurs.

Negations of C and E are as follows:

(C) Some events that occur over time have only one cause.
(E) More than one asteroid hit Earth during the extinction.

Negating (C) does not harm Trent's argument. It makes it better by suggesting that something other than an asteroid could have been the sole cause, since the asteroid was too small.

In fact, (C) is not a contender, and did not need to be negated in the first place. Answer choice (C), when it is not negated, states that all events that occur over time have more than one cause. Therefore, Trent cannot assume answer choice (C), or he would have to admit that an asteroid could be one of several contributing causes.

Negating (E) harms Trent's argument. He doubts the asteroid extinction theory because the asteroid he knows about was too small. But if more than one asteroid hit, he could be wrong that extinction was not caused by asteroid.

[ShannonOh22]

Wouldn't the negation of answer choice B destroy Trent's argument, therefore making it an acceptable answer to a Nec. Assumption question?

B) "dinosaurs in the neighborhood of an asteroid impact but not within the zone of direct impact would have survived such an impact"
Negated - "dinosaurs in the neighborhood of an asteroid impact but not within the zone of direct impact would NOT have survived such an impact"

This clearly goes against his argument that the asteroid was not the cause of the extinction. It directly addresses both the asteroid, and the impact zone/crater that both Selena and Trent mention.

E doesn't seem to have the same impact on Trent's argument.

E) "No more than one large asteroid struck the Earth during the period when the dinosaurs were becoming extinct"
Negated - "More than one large asteroid struck the Earth during the period when the dinosaurs were becoming extinct"

This doesn't destroy Trent's claim that there must have been something else that caused the extinction...perhaps two asteroids struck the Earth. So what? Doesn't seem to do much of anything to his argument at all...

Can you please let me know how and why E is the right answer on this one?

[KelseyWoods]

Hi Shannon!

As Brook stated, negating (E) harms Trent's argument. His premise is that the asteroid crater he knows about is not big enough to create enough dust to result in extinction. But if there was another, larger asteroid that hit the Earth, maybe that asteroid could be responsible for the extinction.

The negation of answer choice (B) does not attack this argument because it's still only talking about dinosaurs "in the neighborhood" of the asteroid impact, not a worldwide extinction. So even if it killed the dinos in the neighborhood, it still wouldn't be responsible for the total extinction of the dinosaurs.

Hope this helps!

Best,
Kelsey

[sunshine123]

Howdy,

One of the proctors noted that the negation of C yields:

C) Some events that occur over time have only one cause.

It seems like the proctor negated two things in the sentence: first, the mention of "any" event, and then the mention of "many causes"

Was the procedure to negate two things in the sentence? If so, how do we know that was the right thing to do in this case? More generally, when does a sentence necessitate that one negate two of its elements? Moreover, in the example above, isn't the negation of "any" none?


Best Regards,
Sunshine

Best regards

[atierney]

Hello,

I can't speak for the proctor, but hopefully I can shed some light (semi-intended!) on the answer choice here. The negation, or the contrapositive of C would if an event has only one cause, then it must not have occurred over a long period of time. Now, this is fine, and it certainly means that, if true, a single asteroid could not have caused the extinction. However, this is not what Trent is arguing, mainly his argument does not hinge on how many causes there are (where here, asteroids, even a multitude of asteroids is only a single cause), but rather on the impact (again) of a single cause. Here, his argument states that the impact of asteroids in general would not have caused the requisite dust needed to cover the sky completely. C is really a shell answer choice that is designed to be a trap in this regard.

Let me know if you have further questions.