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Zorluk: ZorIdentifying Necessary Assumptions

Ecologist: In the region's heavily logged forests, the population of the native spotted owl has plummeted. Conservationists argue that the logging of old-growth trees destroyed the owl's necessary nesting habitat, causing the decline. However, a recent survey shows that the invasive barred owl, which aggressively competes with the spotted owl for prey, recently expanded its range into these exact same logged forests. Therefore, the drastic decline in the spotted owl population is primarily due to competition from the invasive barred owl, rather than the loss of nesting habitat.

Which one of the following is an assumption on which the ecologist's argument depends?

  1. The spotted owl population had not already experienced its drastic decline by the time the barred owl expanded into the logged forests.Cevap
  2. B
    The barred owl's expansion into the logged forests was not facilitated by the destruction of the old-growth trees.
  3. C
    The spotted owl population would not have declined at all if the barred owls had not entered the region.
  4. D
    The logging of old-growth trees did not reduce the overall availability of the prey for which the two owl species compete.
  5. E
    Barred owls are capable of outcompeting spotted owls in pristine, unlogged old-growth forests as well.

Cevap

The correct answer is the option stating that the spotted owl population had not already experienced its drastic decline by the time the barred owl expanded into the logged forests.
The correct answer uses the 'Defender' assumption model to protect a causal claim from a timeline flaw. The ecologist concludes that competition from the 'recently' arrived barred owl caused a decline that has already occurred. For a recent arrival to cause an event, the event cannot have completely occurred before the arrival. If we negate this option—meaning the spotted owls had already drastically declined before the barred owls even showed up—then it is chronologically impossible for the barred owls to be the primary cause of that drastic decline. The argument would instantly fall apart.

Adım Adım Çözüm

1
Identify the main conclusion and the premises.
Conclusion: The decline is primarily due to competition, not loss of nesting habitat. Premise: Barred owls recently expanded into the area and compete for prey.
Understanding the exact causal claim is required to find the gap in the reasoning.
2
Analyze the temporal relationship in the stimulus.
The ecologist states the spotted owl population 'has plummeted' (past/ongoing) but notes the barred owl 'recently expanded' (recent past) into the area.
Mismatched timelines between a supposed cause and its effect often reveal the necessary assumption.
3
Apply the Negation Technique to evaluate the options.
Negating the correct option yields: 'The spotted owl population HAD already experienced its drastic decline by the time the barred owl expanded.' This destroys the argument, proving it is the necessary assumption.
A necessary assumption is one that, if proven false, causes the entire argument to logically collapse.

Anahtar Kavram

Identifying Necessary Assumptions via Timeline and Causality
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Konular

Identifying Necessary Assumptions

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