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Question

Difficulty: MediumWeaken

Materials Scientist: Conservators restoring a historic limestone facade observed accelerated surface spalling on sections treated with an ethyl silicate consolidant compared to untreated sections. Because ethyl silicate reacts with ambient moisture to deposit silica without chemically degrading the stone's calcite matrix, the consolidant itself cannot be responsible for the deterioration. Therefore, the accelerated spalling must be caused entirely by localized environmental factors, such as wind-driven salt spray.

Statement: The finding that ethyl silicate deposits an impermeable silica layer that traps evaporating groundwater beneath the stone surface during freeze-thaw cycles, if true, weakens the materials scientist's argument.

Answer: Answer

Answer

True. The additional evidence directly weakens the materials scientist's conclusion by establishing that the consolidant can induce mechanical failure even if it remains chemically non-reactive.
The conclusion of the argument attributes the accelerated deterioration solely to localized environmental factors, reasoning that because the consolidant is chemically inert with respect to calcite, it cannot cause damage. The supplementary statement shows that the consolidant introduces a serious physical vulnerability (trapping moisture beneath an impermeable barrier during freeze-thaw cycles). Because this demonstrates that the consolidant is indeed responsible for the increased spalling via physical rather than chemical means, the statement successfully weakens the scientist's argument.

Step-by-Step Solution

1
Analyze the core argument structure in the stimulus
Premise 1: Spalling was accelerated on treated sections. Premise 2: Ethyl silicate does not chemically degrade the calcite matrix. Intermediate Conclusion: The consolidant cannot be causing the damage. Main Conclusion: Localized environmental factors must be the sole cause of the accelerated spalling.
Identifying the explicit premises and the inferential leap between lack of chemical degradation and complete lack of causal responsibility is necessary to evaluate the argument.
2
Identify the key gap and assumption in the author's reasoning
The author assumes that chemical degradation is the only mechanism by which the consolidant could cause the limestone facade to deteriorate.
Weaken questions frequently target false dichotomies or overlooked alternative mechanisms.
3
Evaluate the impact of the statement on the conclusion
Trapping internal moisture and inducing freeze-thaw spalling establishes a physical mechanism of degradation caused directly by applying the consolidant, refuting the claim that the consolidant is harmless.
Providing a valid causal link between the consolidant and the observed spalling directly undermines the author's conclusion that environmental factors alone are responsible.

Key Concept

Alternative Causal Mechanisms and False Exclusions
Estimated Time:1m 15s
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Weaken

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