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June 2007, Logical Reasoning 2, Question 5


Question five, when the question stem asks for something that could be assumed in order for the conclusion to follow logically, you're dealing with a sufficient assumption question. On a sufficient assumption question, your job is to find an answer choice that when added to the evidence already given in the argument will guarantee that the argument's conclusion is absolutely true.

The conclusion of this argument is helpfully flagged by the conclusory keyword, thus. Thus, the early entomologist was wrong. Now in order to know which early entomologist we're talking about, we have to go back up to the first sentence. That's the early entomologist who inferred that the ants that they saw were bringing food to their neighbors.

The evidence that were given is two-fold. First, a little bit of setup evidence. There was an early entomologist who observed some ants carrying particles to neighboring ant colonies and then there has been some further research that's revealed that the ants were emptying their own colony's dumping site. So we know that they were carrying particles.

We know that those particles came from their dumping site. The conclusion is that the ants were not bringing food to their neighbors. So go to the answer choices looking for something that will help you prove the conclusion absolutely true. Answer choice A, answer choice A says that ant societies don't interact in all the same ways that human societies interact.

Well, that may be interesting. It doesn't tell us whether those particles contained any food in them or not. Just that there's some things that humans do the ants don't do. Whether that includes bringing food to your neighbors, we don't know. So answer choice A is not our answer. Go to answer choice B.

B tells us that there is only weak evidence for the view that ants have the capacity to make use of objects as gifts. Weak evidence isn't no evidence. So it's still possible for our early ethnologist to be right, if it turns out that the weak evidence is right. So B is not our answer, go to C.

C tells us that ant duping sites do not contain particles that could be used as food. Now, this is our answer. So we know that the ants were taking the particles from their dumping site. If dumping sites never have food in them, then those ants were definitely not giving food to their neighbors.

Answer choice C is exactly what we want, because it proves 100% the conclusion is true. Now, a quick look at the other answers to see why they're wrong. Answer choice D is wrong, because it's about the ants that the particles were brought to. Nothing matters about them.

What matters is the ants that were doing the bringing, are they bringing food? Answer choice E tells us that the entomologist in the argument retracted his conclusion. Now, what that entomologist thought about his own work on down the road doesn't tell us whether it was right or not. He could have been wrong to retract his work.

So since this does not prove 100% that he was wrong, it is not our answer. Answer choice C is the answer.

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