#2 - Dr. Theresa Pagano, a biologist, has found that the

[Administrator]

Complete Question Explanation

StrengthenX-CE. The correct answer choice is (C)

Interpreting a correlation between two events as if they are causally related is a classic mistake in cause-and-effect stimuli. In this instance, Dr. Pagano observes that the northward shift of the butterflies is correlated with the northward shift of the warm zones in the global climate, and concludes that the changing climate is responsible for the northward movement of the butterflies:

• Cause Effect
  Climate change Northward shift of butterflies

To strengthen this argument, you need to support the conclusion that climate change is the proper cause for the given effect. Since this is a StrengthenX question, the correct answer will not strengthen the argument.

Answer choice (A): If checkerspot butterflies are known to be affected by small temperature regulations, then the northward shift of the warm zones can certainly affect the prevalence of the butterflies in those regions. This answer choice strengthens the argument and is therefore incorrect.

Answer choice (B): If climate affects the plants on which the butterflies depend, that can explain the northward movement of the butterflies. Since climate change is still indirectly responsible for the observed effect, this answer choice strengthens the argument and is therefore incorrect.

Answer choice (C): This is the correct answer choice. If the butterflies can easily adapt to a wide range of climatic conditions, it is even less likely that the climate change would force their population to shift northward. By suggesting an alternate cause for the given effect, this answer choice actually weakens the argument.

Answer choice (D): If abnormally low temperatures have been correlated with a reduced butterfly population, it is reasonable to infer that butterflies are adversely affected by low temperatures and that the northward shift of the warm zones can increase their prevalence in those regions. This answer choice strengthens the argument and is therefore incorrect.

Answer choice (E): This answer choice strengthens the conclusion by analogy and is therefore incorrect.

[sunshine123]

With regard to answer choice C: I understand how the assertion that the butterflies can adapt to a wide range of temperatures weakens the argument. However, what of the second part of that answer choice that refers to the butterflies ability to adapt to GEOGRAPHIC conditions? This information DOES help the argument since the inability to adapt might otherwise be a problem for these butterflies. However, maybe even that information DOES not help the arg since we already know that they ARE in these places so who cares if they can adapt, looks like they have done so anyway? In the event that that PART of the answer choice DOES help the argument, on what grounds may we eliminate it? On the simple grounds that PART of it damages the argument? Is that the takeaway here? If we're looking for a damaging answer choice and there is answer choice that both weakens AND strengthens the argument in question does it by definition still weaken the argument and hence the right answer?

Thanks!

[Robert Carroll]

sunshine,

The question of what to do if an answer partly weakens and partly strengthens doesn't arise with answer choice (C) here. Nothing about that answer is good for the argument. There is no indication in the stimulus that geographic conditions have changed, and in reality, geographic conditions don't seem like the kind of conditions that could change very quickly anyway. Thus, if the butterflies are moving to more northern regions, the fact that they are geographically able to adapt easily (and therefore aren't moving because of geographic changes) doesn't seem to eliminate a "live" alternative cause for their movements at all.

Therefore, some of answer choice (C) is bad for the argument and the rest is irrelevant. There's no need to weigh the pros and cons - this answer choice is one-sided.

Robert Carroll