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- Thu Feb 20, 2014 12:00 am
#33126
Complete Question Explanation
Weaken—#%. The correct answer choice is (B)
The weakness in this argument is difficult to spot because the terms used in the stimulus are designed to focus you too narrowly on the numbers involved with the increase in population and the fresh water supply. The use of these terms is very subtle, and the logical gap is very easy to miss.
The stimulus author disagrees with people who claim that water shortages will plague humankind in the near future unless population growth trends change. While the claim is conditional—notice the term “unless”—the focus of the conclusion is not on conditional reasoning. Instead, it is on the numbers involved with “population growth trends” and “water shortages.”
The author concedes that Earth’s human population is increasing, but disagrees with the water shortage claim because the population uses only a relatively small fraction of the supply of fresh water. Here is where the subtlety comes into play. The terms used in the premises and the conclusion are similar, but not identical. The difference between these terms permits a strong prephrase.
The conclusion refers to “population growth trends,” while the premise refers to the increase in human population. Although the increase in human population is a part of what makes up the population growth trends, the growth trends also involve where in the world those increases are occurring.
Along the same line, the conclusion refers to “water shortages,” while the premise talks about the “supply of fresh water.” This difference is very subtle. When you discuss the supply of fresh water, using the singular “water,” you are talking about the total amount of fresh water available on the planet. If there is not enough fresh water, in total, on the planet, then there is a fresh water shortage, not fresh water shortages. The use of the plural for “shortages” implies a shortage in more than one location.
Taken together, these two differences between the terms used in the premise and those used in the conclusion provide a very strong understanding of the flaw in the stimulus: the conclusion is about the fresh water shortages in various locations resulting from the increasing human population in those areas, while the premise only provides evidence about the relationship of the human population as a whole compared to the total amount of fresh water available on Earth. So, the prephrase in this Weaken question is that the author has failed to consider the local differences in population growth and the supply of fresh water. For example, there may be plenty of fresh water to support an increasing population in Minnesota (i.e., the “land of 10,000 lakes”), but not enough fresh water to support an increasing population in Death Valley National Park (the driest place in North America).
Answer choice (A): The argument does not rely on the accuracy of future predictions. Instead, the conclusion expresses disagreement with the view that should present population growth trends remain unchanged, then water shortages will plague humankind in the near future.
Answer choice (B): This is the correct answer choice. The prephrase focused on the difference between a shortage of water and water shortages. If it is true that the amount of fresh water available to meet the needs of the human population varies significantly from region to region (i.e., the needs in Minnesota are different than those in Death Valley and are different than those in New York City), then there is reason to doubt the conclusion, and to think that there may be cause to worry about water shortages even though the human population uses only a relatively small fraction of the total supply of fresh water.
Answer choice (C): The premise established that the human population uses only a relatively small fraction of the supply of fresh water. Unless there is some other issue, such as the water not being in the places where the people need it, there is no reason to think that conservation methods are necessary.
Answer choice (D): The conclusion in the stimulus dealt with a limited time frame, stating that the water shortage would occur in the near future. This answer choice deals with what will occur “eventually,” a different, and ambiguous, time frame. Accordingly, this answer has no effect on the conclusion.
Answer choice (E): The conclusion had to do with the amount of fresh water available for use by humankind, not with the various ways in which people will use the water. So, comparing the rates of increase of two uses of fresh water is irrelevant to the conclusion, especially since this answer choice does not offer any reason to think the amount of fresh water used will increase to levels that are problematic.
Weaken—#%. The correct answer choice is (B)
The weakness in this argument is difficult to spot because the terms used in the stimulus are designed to focus you too narrowly on the numbers involved with the increase in population and the fresh water supply. The use of these terms is very subtle, and the logical gap is very easy to miss.
The stimulus author disagrees with people who claim that water shortages will plague humankind in the near future unless population growth trends change. While the claim is conditional—notice the term “unless”—the focus of the conclusion is not on conditional reasoning. Instead, it is on the numbers involved with “population growth trends” and “water shortages.”
The author concedes that Earth’s human population is increasing, but disagrees with the water shortage claim because the population uses only a relatively small fraction of the supply of fresh water. Here is where the subtlety comes into play. The terms used in the premises and the conclusion are similar, but not identical. The difference between these terms permits a strong prephrase.
The conclusion refers to “population growth trends,” while the premise refers to the increase in human population. Although the increase in human population is a part of what makes up the population growth trends, the growth trends also involve where in the world those increases are occurring.
Along the same line, the conclusion refers to “water shortages,” while the premise talks about the “supply of fresh water.” This difference is very subtle. When you discuss the supply of fresh water, using the singular “water,” you are talking about the total amount of fresh water available on the planet. If there is not enough fresh water, in total, on the planet, then there is a fresh water shortage, not fresh water shortages. The use of the plural for “shortages” implies a shortage in more than one location.
Taken together, these two differences between the terms used in the premise and those used in the conclusion provide a very strong understanding of the flaw in the stimulus: the conclusion is about the fresh water shortages in various locations resulting from the increasing human population in those areas, while the premise only provides evidence about the relationship of the human population as a whole compared to the total amount of fresh water available on Earth. So, the prephrase in this Weaken question is that the author has failed to consider the local differences in population growth and the supply of fresh water. For example, there may be plenty of fresh water to support an increasing population in Minnesota (i.e., the “land of 10,000 lakes”), but not enough fresh water to support an increasing population in Death Valley National Park (the driest place in North America).
Answer choice (A): The argument does not rely on the accuracy of future predictions. Instead, the conclusion expresses disagreement with the view that should present population growth trends remain unchanged, then water shortages will plague humankind in the near future.
Answer choice (B): This is the correct answer choice. The prephrase focused on the difference between a shortage of water and water shortages. If it is true that the amount of fresh water available to meet the needs of the human population varies significantly from region to region (i.e., the needs in Minnesota are different than those in Death Valley and are different than those in New York City), then there is reason to doubt the conclusion, and to think that there may be cause to worry about water shortages even though the human population uses only a relatively small fraction of the total supply of fresh water.
Answer choice (C): The premise established that the human population uses only a relatively small fraction of the supply of fresh water. Unless there is some other issue, such as the water not being in the places where the people need it, there is no reason to think that conservation methods are necessary.
Answer choice (D): The conclusion in the stimulus dealt with a limited time frame, stating that the water shortage would occur in the near future. This answer choice deals with what will occur “eventually,” a different, and ambiguous, time frame. Accordingly, this answer has no effect on the conclusion.
Answer choice (E): The conclusion had to do with the amount of fresh water available for use by humankind, not with the various ways in which people will use the water. So, comparing the rates of increase of two uses of fresh water is irrelevant to the conclusion, especially since this answer choice does not offer any reason to think the amount of fresh water used will increase to levels that are problematic.
), the word "plague humankind" has some elasticity to it. "Plague" doesn't mean wipe out the whole human race, necessarily. On that note, B is the best answer choice, in that portions of humanity can be hurt, in particular regions of the Earth, and that still counts as "plague humankind", even if not all humanity is affected.