Re: Lyme disease is caused by a bacterium transmitted to humans by deer ti
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15 Aug 2016, 13:00
This question is a tricky one. Let us begin by first understanding what the question is asking.
"Which of the following would it be most important to ascertain in evaluating the argument?"
In other words, the answer to which of the following questions would be the most useful in determining whether or not the author's argument is logical.
In order to answer this question, we must first understand the author's logic.
The argument can be simplified as follows:
[*]Lyme disease is transferred to humans by infected deer ticks.
[*]When deer ticks are in the larval stage, they feed on two species:
[*][*]1. White-footed mice; and
[*][*]2. Other species.
[*]White footed mice carry Lyme disease, and larvae who feed on infected mice also become infected.
[*]Other species do not carry Lyme disease, and so larvae who feed on other species do not become infected.
[*]Therefore, increasing the population of 'Other species' will lead to a decrease in the number of infected larvae.
Because this is an evaluate the argument type question, we know that there is probably something wrong with this argument. In this case, the author is making an assumption. Understanding what this assumption is will help us to evaluate which of the answer choices is best, because the best answer choice will address this assumption directly.
So, what is the author's assumption? In this question, the author actually states his/her assumption in the conclusion. The structure of the author's conclusion is A leads to B leads to C, where B is the assumption.
A: Increase population size of other species.
B: (Assumption) "more of the larvae would be feeding on the uninfected hosts"
C: The number of newly infected deer ticks will decrease.
Are we absolutely certain that by introducing new hosts, the larvae will prefer to feed on this host as opposed to the white-footed mice? No, we are not certain. So, when we examine the answer choices, we will look for an answer choice that makes this assumption (B) a fact. (A common mistake on this problem is searching for an answer to the author's final point (C). This would be the case if we were looking to weaken the argument. However, this is not our goal. Our goal is to determine whether or not we do in fact have an argument.)
The answers:
A: Irrelevant. Whether or not the 'Other Species' is found only in the same areas in which white-footed mice are found does not help us address the assumption. If they are found only in the same are, it is still likely that the larvae may feed on the new host, but it is just as likely that they may not begin feeding on the new host. Furthermore, even if the 'Other species' is found in places other than those in which white-footed mice are found, this would not inhibit the larvae from feeding on the new hosts, because they may still be present in the areas inhabited by the white-footed mice.
B. If the population size is currently limited by the number of available hosts to feed on, then introducing a new host would remove this limitation, and the larvae would in fact begin feeding on the 'Other species.'
Furthermore, if the population size is not currently limited by the number of available hosts to feed on, then there is no limitation to be removed, and the larvae would not begin feeding on the 'Other specie,' because they have no incentive to.
In other words, the answer to this question, whether it be yes or no, directly addresses the author's assumption, which, in turn, will help us in evaluating the author's logic. This is the correct answer.
C. This answer may seem correct at first. However, it will only appear to be so if we are assuming the same thing as the author (that the population size is currently limited by the number of available hosts and that introducing a new host will cause the larvae to feed on the new host.
Only if we accept this assumption to be true would we be concerned about what steps should be taken next to control the infected deer tick population. However, since the question deals with evaluating the author's argument (and the validity of the author's assumption), this answer choice is irrelevant, because it does not address the author's assumption (in fact, it maintains it), and as a result does not help is in evaluating the author's argument.
D. This answer choice is similar to answer 'c'. It maintains the author's assumption rather than addressing it.
Remember: The author is assuming that the introduction of a new species will cause deer ticks to feed on this new species.
Because this answer choice assumes that the current population size is currently limited by the number of 'Other species' available to feed on, it does not help us in evaluating the validity of the original assumption.
E. This answer choice is out of the scope of the author's argument. The author is concerned about a reduction in the spread of Lyme disease. Other diseases are irrelevant to this argument.
In summary, when we are given an evaluation question, we must first understand the author's line of reasoning and then search for a flaw in this line of reasoning. The best answer choice will directly address this flaw.