More Solitary Passages Questions - - Question 18

Which one of the following, if true, most clearly weakens the rate-of-speciation hypothesis as it is described in the...

farnoushsalimian July 21, 2022

C vs. E - please help, implications for how weaken questions are treated in RC

If these are alternative and competing hypotheses intended to explain the phenomenon in question, I don't understand why answer choice E is correct. Answer choice E says that most subgroups become extinct rapidly within a tropical zone, but this does not NECESSARILY weaken the hypothesis/theory. Most subgroups can become extinct rapidly in tropical regions so long as subgroups become extinct more comprehensively and/or at a faster pace in more polar regions. That the extinctions happen quickly amongst divergent subgroups near the equator should not in itself weaken the hypothesis. The pace of extinctions should only weaken the argument if it is demonstrated to be faster than more polar regions. Answer choice C addresses the shortcoming of a competing theory, thereby strengthening it. Since it is a competing theory, can we not infer that strengthening it weakens competing theories (ie. it weakens the rate of speciation hypothesis)?

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farnoushsalimian July 22, 2022

Any clarification would be really appreciated

Emil-Kunkin July 22, 2022

Hi Farnoush,

I think that E does weaken the speciation rate hypothesis (the one introduced in the final two paragraphs). It does not have to destroy the argument, and as you pointed out, it does not destroy the argument, but it does undermine it. The argument is predicated on the idea that tropical subgroups are more likely to survive. E gives us evidence that would make us doubt that premise. It does not completely contradict the premise, but it is certainly cause for doubt. This is much the same as an LR weaken- the correct answer does not have to destroy the argument, only undermine.

I think that C actually strengthens the argument. C tells us that higher energy influx (which we know happens at the tropics) leads to less extinction. Thus, there would be comparatively less extinction among subgroups in the tropics than there are near the poles, strengthening the final hypothesis.