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Gas-fired and oil-fired - Weaken

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Gas-fired and oil-fired - Weaken

by sparkles3144 » Sun Feb 16, 2014 6:15 pm
Gas-fired and oil-fired power plants emit some pollutants into the air. However, coal-fired plants, as presently engineered, emit far more noxious air pollutants, causing acid rain to fall hundreds of miles away from the plants themselves. Therefore, in order to reduce air pollution, we should close down the coal-fired plants and replace them with gas and oil-fired plants.

Which of the following, if true, would most weaken the conclusion above?

A. In addition to the air emissions from coal-fired power plants, mining coal can pollute water, while gas and oil-fired plants pollute only air.

B. Coal plants can easily be redesigned to eliminate most emissions into the atmosphere.

C. Gas-fired power plants are more cost efficient than coal-fired power plants.

D. As supplies of oil decline, the demand for natural gas and coal will increase.

E. Engineers have developed a model to reduce emissions from oil and gas-fired plants to an imperceptible amount.

Is it B?
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by [email protected] » Sun Feb 16, 2014 9:42 pm
Hi sparkles3144,

This CR question is an example of a WEAKEN question. We'll need to understand the logic behind the prompt and then find an answer that ATTACKS the logic.

The Facts:
-Gas-fired and Oil-fired power plants emit some air pollutants
-Coal-fired plants, at PRESENT, emit far MORE noxious air pollutants

The Conclusion:
-The REDUCE air pollution, we should close down Coal-fired plants and replace them with Gas-Fired and Oil-fired plants

The Logic:
Since the PRESENT version of Coal-fired plants cause so much MORE pollution (by comparison), if we want to REDUCE air pollution, we need to replace the Coal plants with Gas and Oil plants. This logic holds true if Coal plants can't be improved and if the other plants (Gas and Oil) don't cause some other kind of danger in other ways.

To WEAKEN the logic, we'll need an answer that either tells us that Coal plants can be improved to emit less pollution than Gas and Oil plants or that Gas and Oil plants cause other pollution that's worse than what Coal plants currently do.

The correct answer B explains how Coal plants can be improved (and their pollution significantly decreased).

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by Matt@VeritasPrep » Thu Feb 20, 2014 2:56 pm
Another approach:

To weaken an argument, you want to argue for the OPPOSITE conclusion.

If the conclusion of this argument is "Closing coal plants will reduce air pollution", we want to argue the opposite: "Closing coal plants MAY NOT reduce air pollution". So any answer that suggests this is fine.

A:: This tells us that coal plants are even worse than we thought - not at all what we want here!
B:: Hey, here's something telling us that coal plants aren't necessarily air polluters ... looks good.
C:: Cost-efficiency has nothing to do with air pollution, so this is out of scope.
D:: Demand is also out of scope.
E:: This would argue for the original conclusion, as it suggests that oil- and gas-fired plants pollute the air less than coal-fired plants do.

B it is!
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