A scientific study provides

Answer choices

1. A

   Correct64% picked this

   some of the crows that shrieked at and dive-bombed people wearing the masks were not among the crows

   Why this is right

   The language here ("some") is lovably weak. How do we know that our author was clearly thinking that at least one of the shrieking / diving crows was someone who wasn't around for the first incident? Well, where else would this notion of "crows can pass their concerns on to other crows" come from otherwise? If the author thinks that this study suggests that crows can pass on their concerns, he must be thinking that some of the shrieking / diving crows had been warned by other crows about these people. If we negate this answer, we get a double-negative "none of the crows were not among the crows that had been trapped", which translates into "all of the crows that shrieked / dived were among the crows that had been trapped". If all the crows in this shrieking / diving incident were crows who were originally trapped, then where is the evidence that crows are passing their concerns on to others? Negating this answer badly weakens the second half of the conclusion. If a conclusion makes two claims, you can weaken the argument by impugning claim 1, claim 2, or both.

   Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.

   64%
2. B

   Too Strong: always Reversed Logic24% picked this

   crows that perceive an individual as threatening always respond by shrieking

   Would it matter if they only responded to threatening people with shrieking and dive-bombing 99% of the time, rather than 100% of the time? Of course not. That's why we know the author doesn't need to assume that in 100% of cases, crows react to threatening people with shrieking and dive-bombing. Given that "always" is conditional strength, we could look at this answer as a conditional and ask ourselves, "Did the author make this move?" perceive someone ? shriek and dive bomb as threatening That's actually the reverse of what the author did. He knows that the crows shrieked and dive-bombed, and from there he assumes that the crows recognized the people wearing masks as threatening. So our author is really assuming that if they shriek / dive-bomb ? it's because they perceive someone as threatening

   24%
3. C

   Out of Scope2% picked this

   most birds of any species will regard a person as threatening if they see crows shrieking at

   Out of Scope: any species Too Specific: most "Most" is wrong 99.5% of the time we see it on Necessary Assumption, since the difference between saying "most birds are X" vs. "not the case that most birds are X" is the difference between saying "it's at least 51%" and "it's at most 49%". Negating 'most' makes such a slight difference, that the negation almost never weakens, so the answer is almost always wrong. The fact that this answer says "most birds of any species" instantly tells us it's out of scope, since this argument is strictly about crows, so the author doesn't need to be assuming anything about other types of birds.

   2%
4. D

   Opposite4% picked this

   even in places where crows have never been captured, most crows will shriek at and dive-bomb

   This also use the word "most", which we explained in (C) is wrong on Necessary Assumption 99.5% of the time we see it. But more egregiously, this answer goes against what the author believes. She doesn't think that crows will shriek and dive-bomb at just any ol' person who's wearing a caveman mask. She is arguing / assuming that the crows shrieked and dive-bombed these caveman mask-wearers specifically because they recognized them as the devious trap & release cavemen from years ago. So our author is assuming that most crows would not usually just shriek and dive-bomb; she thinks this is a "special" (not common) response that was triggered by a memory of the trauma inflicted by the mask-wearers.

   4%
5. E

   Too Specific6% picked this

   crows can distinguish between people who are wearing caveman masks and those who are not, but they cannot

   We have no idea what the author thinks, if anything, about this unknown comparison. Our author is saying that crows can recognize threatening people -- she doesn't say "as long as they're wearing a mask ..." If we negated this answer and said, "Hey, author, crows can distinguish between mask wearers and non-mask wearers, as well as recognize individual human faces", would that hurt the argument? No, it kind of sounds like it would even help the author to establish that crows can recognize individual human faces.

   6%