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Difficulty: HardRuling Out Alternate Explanations (Defender)

Paleontologist: The extinction of the marine reptile *Thalassadon* was caused by a rapid global cooling event, rather than by a viral pandemic as some scientists have proposed. Fossil records clearly indicate that *Thalassadon* populations drastically plummeted in the higher, colder latitudes hundreds of thousands of years before they disappeared from the warmer equatorial waters.

Statement: The paleontologist's argument logically depends on the assumption that the proposed viral pandemic did not originate in the higher latitudes and slowly spread toward the equator.

Answer: Answer

Answer

True
The statement accurately identifies a necessary assumption. The argument attempts to dismiss the viral pandemic theory by pointing out that the extinction started in colder climates. For this evidence to successfully dismiss the viral theory, the author must assume that the virus itself wouldn't produce that exact same geographic pattern.

Step-by-Step Solution

1
Identify the argument's conclusion and primary supporting evidence.
The conclusion is that global cooling, not a virus, caused the extinction. The evidence is that the extinction occurred in colder, higher latitudes long before it reached warmer, equatorial waters.
Deconstructing the argument structure is required to evaluate any logical assumption.
2
Apply the Negation Test to the candidate assumption in the statement.
The negated assumption is: 'The proposed viral pandemic DID originate in the higher latitudes and slowly spread toward the equator.'
The Negation Test determines if an assumption is logically necessary; if the negated version destroys the argument, the assumption is necessary.
3
Evaluate the impact of the negated assumption on the paleontologist's argument.
If the virus spread from higher latitudes to the equator, it perfectly explains the extinction timeline, invalidating the paleontologist's attempt to use that timeline as definitive proof for global cooling over a virus.
A defender assumption must protect the argument from an alternate explanation of the specific evidence presented.

Key Concept

Ruling Out Alternate Explanations (Defender Assumptions)
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Ruling Out Alternate Explanations (Defender)

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