# LSAT and Law School Admissions Forum

Get expert LSAT preparation and law school admissions advice from PowerScore Test Preparation.

## #25 - Some anthropologists argue that the human species

• PowerScore Staff
• Posts: 8267
• Joined: Feb 02, 2011
#73710
Complete Question Explanation

Flaw in the Reasoning. The correct answer choice is (A).

A conditional argument made by some anthropologists is presented: if early humans had not developed the ability to survive in diverse environments, then the human species would not have survived through prehistoric times. Simplifying that argument, we can use "ASDE" is shorthand for the ability of early humans to survive in diverse environments, and "HS" for the human species survives. The diagram for the claim made by the anthropologists, then, is:

ASDE HS

The author then argues that those anthropologists must be mistaken, on the grounds that there were other early human-like people who did have that ability to survive but who went extinct. The author, then, is saying that the conditional argument is incorrect because some groups that did not meet the Sufficient Condition nevertheless met the Necessary Condition. Of course, this is not a problem, because a Necessary Condition can happen whether a Sufficient Condition does or does not. The author has gotten confused, treating the Sufficient Condition as if the anthropologists thought it was Necessary and vice versa.

As this is a Flaw question, we need only find the answer that correctly describes a flaw in conditional reasoning, a Mistaken Negation or Mistaken Reversal.

Answer choice (A): This is the correct answer choice. This answer describes the conditional flaw, mistaking a necessary condition for a sufficient one. As is typical with conditional flaws, the answer uses the language of conditionality, including words like sufficient, required, and condition.

Answer choice (B): This answer sounds like a mix of causal reasoning and an overgeneralization, neither of which describes the conditional nature of the problem.

Answer choice (C): Another overgeneralization answer, which was not the problem in the argument.

Answer choice (D): Like answer B, this one sounds like it has some causal elements to it, talking about lowering the chances of survival. But the flaw is purely conditional, and this answer does not describe that.

Answer choice (E): Once more we have an answer choice that is causal, while the argument, and the flaw, are conditional. Do not be fooled by causal answers to conditional flaws, or by conditional answers to causal flaws. These are common traps to avoid.
saranash1
• Posts: 168
• Joined: May 21, 2013
#9661
25. I understand how a can be correct but I don't understand why any of the other answers aren't just as good.
Nikki Siclunov
• PowerScore Staff
• Posts: 1364
• Joined: Aug 02, 2011
#9670
Sara,

Can you tell us a bit more about how you approached this question? What precisely made all five answer choices equally attractive? There is a particular type of logical fallacy inherent in this argument (hint: it has something to do with conditional reasoning). If you saw that, then answer choice (A) should have been an easy pick - it's a textbook description of Mistaken Reversal.

So please tell us precisely how (B), (C), (D), and (E) describe logical fallacies also present in this argument.

Thanks!
eober
• Posts: 107
• Joined: Jul 24, 2014
#16453
Hi,

Would you be able to correct the conditional reasoning diagram I have if there is a mistake:

Survived --> Evolved ability to cope with diverse natural environments

example of A.A:
Thrived in a diverse array of environments (can cope) --> (not) survived

Is it correct to say the "condition" mentioned in answer choice is "the coping ability"

Thanks!
BethRibet
• PowerScore Staff
• Posts: 199
• Joined: Oct 17, 2012
#16525
Hi eober,

You're interpreting the condition in the answer choice correctly.

Your diagram from the first sentence is correct. From the second, this is not precisely a conditional statement here. They just tell you that assuming we analogize the rule for humans to the second species, that the necessary condition is met, and that the sufficient condition was not met. It's not wrong to diagram it out in this way, but the critical thing is that they're assuming here that because the necessary was met, the sufficient should have been. That is, this is an example of mistaken reversal, and that flaw is described (analogizing between two cases) in answer choice A.

Hope this helps!
Beth
ChicaRosa
• Posts: 111
• Joined: Aug 23, 2016
#28586
When I did this problem I ended up getting C instead of A and I don't understand why it's wrong?

As I read the explanations I noticed that most people graphed the stimulus like this:

Survival Evolved ability to cope with diverse natural environments

When I diagrammed it looked like this: Evolved ability to cope with diverse natural environments Survival

And as I'm reading it the way that the original statement (which is the one I diagrammed) is also the same as the diagram I saw on here because it's the contrapositive.

I think I misread the one I originally diagrammed and used it with the next stimulus about a similar prehistoric species that are related to humans and ended up doing this:

P1: Evolved ability to cope with diverse natural environments Survival

P2: Evolved ability to cope with diverse natural environment Survival

which led me to think that survival was the necessary condition instead of the sufficient condition and vice versa with Evolved ability to cope... which led me to Answer choice C.

So if I understand this is A correct because of the contrapositive of the original statement while connecting it to the second stimulus?

P1: Survival Evolved ability to cope with diverse natural environments

P2: Evolved ability to cope with diverse natural environment Survival

If I look at it this way it looks like the necessary is mistaken for the necessary for the sufficient condition. In this case the second premises commits a Mistaken Negation.

Is my explanation right?

Thank you!
Claire Horan
• PowerScore Staff
• Posts: 408
• Joined: Apr 18, 2016
#28812
Hi ChicaRosa,

The first statement is a general principle that the anthropologists believe: "The human species could not have survived prehistoric times if the species had not evolved the ability to cope with diverse natural environments."

This can be written as: did not evolve ability to cope did not survive
The contrapositive is: survived evolved ability to cope

The second sentence is an application of the anthropologists' claim: "Australopithecus afarensis, a prehistoric species related to early humans, also thrived in a diverse array of environments, but became extinct."

The author says, "Hence, the anthropologists’ claim is false." In other words, the author is saying that the second sentence is inconsistent with the first. But is it?

The first sentence does not say that the ability to cope is sufficient for survival, but that seems to be the author's misunderstanding of it. In other words, the author has done a mistaken negation (or a mistaken reversal, depending on how you diagrammed the first statement.

It sounds like you understand the problem, but I thought I'd explain it in the way that makes sense to me, in case it helps!

Analyze and track your performance with our Testing and Analytics Package.