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## #23 - A scientific study provides evidence that crows are

KelseyWoods
• PowerScore Staff
• Posts: 1080
• Joined: Jun 26, 2013
#81927
Hi cjv!

As you determined, the literal negation of answer choice (A) would be: "none of the crows that shrieked at and dive-bombed people wearing the masks were not among the crows that had been trapped." But careful with how you interpret the meaning of that statement because it contains a confusing double negative!

Your interpretation was that this said that none of the dive-bombing crows were trapped. But the negation actually says that none of the dive-bombing crows were NOT trapped. That means that all of the dive-bombing crows were trapped. If all of the dive-bombing crows were the ones that had previously been trapped, that would attack the argument that crows pass on information to other crows.

When a negation creates a double negative like we have here, you have to be really careful with how you interpret it because those double negatives are definitely tricky!

Hope this helps!

Best,
Kelsey
cjv
• Posts: 2
• Joined: Dec 05, 2020
#82091
Thank you Kelsey!

However, I am still having a problem with the negation interpretation. Your explanation makes sense, but help me a little more.

Negating answer choice A "NONE of the crows that dive-bombed were NOT among those the crows that were trapped. Why do I still interpret this as if the crows that dive-bombed were not apart of those that were trapped.

If I really simplify the answer choice to "NONE were NOT trapped" it makes complete sense because then they are apart of the group that was trapped.
Rachael Wilkenfeld
• PowerScore Staff
• Posts: 579
• Joined: Dec 15, 2011
#82111
Hi cjv,

Let's break things down a bit. We have two logical opposites for quantity here. We have some crows, or the opposite none of the crows/no crows. We also have the logical opposites of trapped/not trapped crows.

When we take the logical negation of answer choice (A), we only negate the quantity term. If we negate multiple terms, we'll end up negating a different statement.

Let's look at how this works with a more direct example:

Statement: Some Cleveland Browns players were not in the Pro Bowl. This means that there is at least one player on the Cleveland Browns that did not make the Pro Bowl. So anywhere from 1-100% of the Cleveland Browns were out of the Pro Bowl.

Correct negation: No Cleveland Browns players were not in the Pro Bowl. This means that there are no Cleveland Browns players that did not make the Pro Bowl. This is the logical opposite of some being left out---here none are left out. They are all in. 0% of Cleveland Browns did not make the Pro Bowl.

Overnegation (INCORRECT): No Cleveland Browns players were in the Pro Bowl. This example negates both "Some" at the beginning and the "were not in the Pro Bowl." This one means that 100% of the Cleveland Browns players were not in the Pro Bowl. That's not the logical opposite of our original statement---it's included in the original statement.

Let's turn back to our friendly crows.

Statement: Some of the dive-bombing crows were not among those trapped. This means 1-100% of the crows were not trapped. Our negation should say that 0% were not trapped.

Negation: None of the dive-bombing crows were not among those trapped. This means that none (0%) of the crows were not-trapped, so all the dive-bombing crows were trapped. This negation weakens the conclusion that the crows could communicate to others because they could have just been reacting to their own experiences.

Hope that all helped.
lavalsat
• Posts: 13
• Joined: Jan 26, 2021
#85508
I can see how answer A is the correct choice- but I am having trouble with the fact that LSCA expects test takers to assume that crows shrieking and dive bombing equals crows perceiving something as threatening. I feel like that assumption would require at least a basic knowledge of zoology. I'm not sure why it is expected for the average test taker to make that leap. Animals could be shrieking and dive bombing for countless other reasons.

My main question is: If we decided that we cannot make that assumption, isn't answer B also something this argument depends on? Am I missing another reason answer B is wrong?
• PowerScore Staff
• Posts: 3875
• Joined: Apr 14, 2011
#85822
As I see it, lavalsat, the problem with answer B is the use of "always," which is a very strong word that would require some very strong evidence to make it necessary. Doesn't the author only have to assume that sometimes crows behave that way when they feel threatened? You're right that the author is making that assumption, too, but we don't have to know anything about zoology to see that. If answer B had said that crows who behave that way at least sometimes do so because they perceive a threat, then it would be a great answer. That's why B is such an attractive trap answer!

Here, the author argued that crows not only recognize a threat, but they can pass on that info to other crows. How did they get that idea? Only if they assumed that at least some of the crows who behaved that way were not the same crows who had originally been trapped by people in those masks. Otherwise, there would be no reason to believe the info ever got passed on.

There can be many assumptions in an argument. You identified one, and answer A identified another. Another would be that crows do not always consider people to be a threat, and another would be that they do not see something threatening in the masks themselves. If either of those last two were false, then there would be no evidence that any crows recognized anything!
andrewb22
• Posts: 18
• Joined: May 04, 2021
#87135
How would you negate answer (E)?

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