Q25 - Some anthropologists argue that

[dan]

25. (A)
Question Type: Identify the Flaw
The argument made by some anthropologists is that if humans survived then we can conclude that they had the ability to adapt to diverse environments:

survival (sufficient condition) -> ability to adapt (necessary condition)

The author makes a suspect conclusion: the anthropologists are wrong because one case exists in which a species had the ability to adapt but did not survive. In other words, the author assumes that "survival -> ability to adapt" implies "ability to adapt -> survival." The author has reversed the logic and confused the sufficient condition with the necessary condition. Ability to adapt is NOT sufficient to cause survival, as a species may have any one of many other shortcomings that could lead to extinction. Answer (A) expresses this flaw in logic.

This is a confusing argument, so let’s try an analogous argument that contains the same flaw:

Many people say that because John lives in San Francisco he therefore lives in California. But these people are wrong because I know someone who lives in California who does not live in San Francisco.

In this argument, San Francisco is sufficient to require California (someone living in San Francisco MUST live in California), but living in California is NOT sufficient to require San Francisco, is it? It would be an error to assume that it does. The author of the argument makes a similar mistake.

(B) is not an error made by the argument.
(C) is not an error made by the argument. A generalization is not made from a specific case.
(D) is very tempting. It is incorrect, though, because the author doesn’t necessarily fail to consider that the species may have had some characteristics that lessened its chances of survival. Rather, the author errs in concluding, regardless of what he or she believes about the species’ other characteristics, that the species’ ability to adapt was in itself sufficient to guarantee survival.
(E) is in incorrect because it introduces causality. This argument does not introduce any cause/effect relationships. Remember, conditional relationships are NOT necessarily causal relationships.


#officialexplanation

[zl7391e]

I may very well misfire, but the above analysis (seems to me) does not address a second flaw in the argument.
I think the stimulus has two flaws (1) confuse what's necessary with what's sufficient and (2) assuming two similar yet distinct sets have the same property.

My reason for flaw (2) is that anthropologists are talking about human species. And the argument tries to refute anthropologists' claim by a counterexample. But that counterexample is about a species that is only related to human species; it does not belong to the set of human species.

So B would be correct in pointing out the flaw if it's instead worded:

takes for granted that if one species had a characteristic that is required to (not enable it to) survive certain condition, at least one related species must have had the same characteristic in order to survive.

In this way, the analogous argument in the above analysis does not have quite the same flaws as the stimulus

This is a confusing argument, so let’s try an analogous argument that contains the same flaw:

Many people say that because John lives in San Francisco he therefore lives in California. But these people are wrong because I know someone who lives in California who does not live in San Francisco.

This is because 'someone' is still human. I think it would be the same if we change "someone" to things that is similar to humans but does not belong to the set of humans. Maybe, apes.

Anyway, A is still the correct answer choice because A not only points out flaw (1) but also it is compatible with flaw (2), since "in one case" refers to human species and "in a similar case" refers to "a prehistoric species related to human species case". Frankly, I think flaw (2) is probably a minor issues and we can definitely solve this problem quicker without noticing or thinking too much about it.

[maryadkins]

You're right that there is a term shift between human species and this prehistoric related species, which (B) and (C) try to play on. In another question with different answer choices, this could very well be where the argument is most vulnerable to criticism. But in this question, be careful about trying to impose that term shift on the existing wrong answer choices to make them right--(B) is actually saying something can be boiled down to, "If humans had the ability to adapt and that's how they survived, at least one related extinct species must have had the same ability to adapt, too."

The argument already tells us that there is at least one prehistoric, extinct species had the same ability to adapt as humans--so the second, necessary condition in (B) is met. If anything, perhaps (B) strengthens the argument.

You're exactly right when you say (A) identifies the fundamental reasoning flaw, but without dealing with the term shift in the argument, and that's okay--it's still the fundamental reasoning flaw. Dan's analogy could be re-written with apes, like you suggested, but everyone knows apes in California make terrible friends.

[shaynfernandez]

I frequently get confused when conditional statements contain two negatives. Such as,
"human species could not have survived prehistoric times if the species had not evolved the ability to cope with diverse environments."

Can and how would you cancel out the "could not survive" and the "not evolved the ability to cope with diverse environments".

If this is not an appropriate time to negate the two terms when is it appropriate?

Thanks

[deedubbew]

I think the key here is that D weakens the argument. This is a flaw identification question. It does not ask you to weaken the argument.