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Question

Difficulty: MediumWeaken

Consider the following argument:

Ecologist: Many urban municipalities are replacing high-pressure sodium streetlights with broad-spectrum white LED lamps to reduce electricity costs. Over the past two years, surrounding agricultural zones near cities adopting LEDs reported a 20 percent decline in the nocturnal pollination of night-blooming crops by moths. Because white LEDs emit substantial short-wavelength blue light, which is known to disorient adult moths and suppress foraging activity, the switch to white LEDs is the direct cause of this agricultural pollination decline.

Statement: The finding that agricultural zones surrounding these cities simultaneously introduced a broad-spectrum chemical treatment targeting nocturnal insect populations, if true, weakens the ecologist's argument.

Answer: Answer

Answer

True, because introducing a plausible alternative cause for the pollination decline directly weakens the ecologist's causal conclusion.
The evaluated statement is correct (True) because a standard method of weakening a causal claim is to provide an alternate cause for the observed effect. The ecologist concludes that urban LED lighting caused the agricultural pollination decline. Demonstrating that the agricultural zones themselves introduced an insect-targeting chemical treatment during the same period provides an independent explanation for the reduced moth population and pollination activity, substantially weakening the ecologist's conclusion.

Step-by-Step Solution

1
Isolate the conclusion and the supporting evidence in the stimulus.
Conclusion: The switch to white LEDs is the direct cause of the 20 percent decline in nocturnal crop pollination. Evidence: White LEDs emit blue light known to disorient moths, and the decline coincided with the LED rollout over the past two years.
Accurately identifying the structural core of the argument is required before assessing any potential weakening effect.
2
Identify the unstated assumption and the vulnerability of the causal reasoning.
The ecologist assumes that no other factor introduced during the same two-year window accounts for the reduced moth activity in the agricultural zones.
Causal conclusions on the LSAT are inherently vulnerable to alternate explanations for the observed phenomenon.
3
Assess the impact of the supplementary statement on the author's conclusion.
If agricultural zones introduced an insecticidal chemical treatment at the same time, this treatment offers a direct, alternate reason for the decline in moth pollination independent of urban lighting.
Providing an alternative cause directly undermines the claim that urban LEDs were the sole or direct cause, confirming the statement is True.

Key Concept

Weakening a causal argument by introducing an alternative explanation for the observed effect
Estimated Time:1m 0s
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Weaken

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