Logical Reasoning

PT114 · S2 · Q17 Selena: Asteroid impact on the

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Selena: Asteroid impact on the Earth caused the extinction of the dinosaurs by raising vast clouds of dust, thus blocking the Sun’s rays and cooling the planet beyond the capacity of the dinosaurs, or perhaps the vegetation that supported them, to adapt.

Trent's Conclusion (So)

The cause of the dinosaur extinctions must have been due not to asteroid impact but some other kind of cause.

Evidence

Based on the crater, we can tell that the asteroid was not large enough to produce the sort of dust you'd need to block out the Sun. Plus, the extinction took many years, not just one or two.

Evaluate

Given that ... the extinction would have taken many years and that the asteroid doesn't seem large enough to create the amount of dust it would take to block out the sun and cool the planet beyond the capacity of the dinosaurs or their plant food to adapt,

How can we argue that ... the extinctions were due to asteroid impact?

Maybe we could argue that the dust does last in the atmosphere for many years. Maybe there was some other simultaneous thing happening that augmented the ability of dust from the impact to cool the earth. Maybe the asteroid impact caused other stuff to happen (like hurricanes) that killed off the dinosaurs.

But importantly, Trent's conclusion isn't limited to saying, "the extinctions weren't due to the Yucatan impact". He's saying something more broadly, that the extinctions weren't due to any asteroid impact; they were due to some other kind of cause. So even if the Yucatan impact wasn't big enough, maybe there was some other asteroid impact that was big enough.

Goal

It seems very hard to predict an answer. It's very unlikely to be a Linking answer. We'll probably find an answer that, if negated, allows us to argue that an asteroid impact was the cause of the dinosaurs' extinction.

17.

Trent's argument assumes that

any collision of an asteroid
Too Strong: any
Trent isn't committed to the idea that 100% of asteroid impacts are on land. He's reacting to Selena's causal story about the Yucatan asteroid, which did occur on land, but he hasn't made it seem like asteroids only hit land. If we negated this and said that some asteroid collisions hit the ocean, would that give us a way to argue that asteroid impact caused the extinction of the dinosaurs? That would only work if we had some common sense idea that a collision hitting the ocean would be more likely to make dinosaurs go extinct than would a land impact. But there's no common sense notion that an ocean impact would be particularly bad for dinosaurs.
1% picked this
dinosaurs in the neighborhood of
Too Specific: impact site's neighborhood
Trent isn't denying that this asteroid killed everything underneath it and he would potentially agree that it also killed everything else in the neighborhood of the impact. He's only saying it wasn't big enough to cause a global extinction. If we negate this and say, "Trent, dinosaurs in the neighborhood of the impact would not have survived it", he would say, "I agree. But the impact wasn't big enough to kick up enough dust to block out the sun and ruin plant life for multiple years."
9% picked this
any event that takes place
Too Strong: Any
The author doesn't have to assume that 100% of events that take place over a long period of time have many different kinds of causes. In fact, he's not even assuming that the dinosaur extinction has many different kinds of causes. He might think it only has one cause, which is not asteroids.
16% picked this
dust from the impact of
Too Strong: No Cooling Effect
Trent is saying that there wouldn't have been enough dust from the Yucatan impact to block the Sun and cool the planet beyond the capacity of dinosaurs or plants being able to adapt. But that doesn't mean he thinks the asteroid had zero cooling effect on the climate. He could happily agree that it probably cooled the climate somewhat, just not to such an extreme extent that it would eradicate a species.
12% picked this
Correct
no more than one large
Why this is right
This reflects Trent's move from arguing that the Yucatan asteroid wasn't big enough to produce the requisite amount of dust to concluding that "extinctions weren't due to (any) asteroid impact". If we negate this answer, it's saying that "there was more than one large asteroid that struck Earth during this period when they went extinct". That would weaken the argument badly, by making creating a possible storyline where it was still an asteroid impact (or multiple impacts) that caused the extinctions. Perhaps there was an asteroid even larger than the one that hit Yucatan. Or perhaps there were several of comparable size over the course of some years, so that there was a large and long-term amount of dust in the air.
Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.
62% picked this

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