#23 - A scientific study provides evidence that crows are

[Luke Haqq]

Hi Henry Z!

Yes, your thoughts generally seem correct, specifically when you note,

It doesn’t have to assume that when perceive threat, crows always shriek and dive-bomb, which is what (B) says.

As you correctly state, this isn't a necessary assumption. The conclusion is, "A scientific study provides evidence that crows are capable of recognizing threatening people and can even pass their concerns on to other crows." Answer choice (B) states, "crows that perceive an individual as threatening always respond by shrieking and dive-bombing," or:

Threat Shrieking/dive bombing

However, it might be the case that they have other behaviors that they exhibit when threatened, beyond shrieking and dive-bombing. Or, to use the Assumption Negation technique, we'd negate this statement and have "crows that perceive an individual as threatening [do not] always respond by shrieking and dive-bombing." If we then insert this negated statement back into the argument, it doesn't make the argument fall apart. This conditional reasoning thus isn't necessary for the conclusion to follow.

Rather, the conclusion involves the statement that crows "can even pass their concerns on to other crows," which would necessitate that at least some of the crows that appeared years later weren't all the same ones as had been trapped. If they were all the same ones, then this experiment wouldn't support the conclusion that the author makes. At least some of them that appeared years latter must be different crows in order for the experiment to support the conclusion that they can pass on concerns about threats to other crows.

[cemck6]

Can someone please explain why (B) is not correct? Thank you!

[Jonathan Evans]

Hi, cemck6!

This is an assumption question; we need to identify an assumption on which the argument depends. In other words, the correct answer will contain a necessary but unstated proposition that is required for the conclusion to be valid. The conclusion has two claims: (1) crows can recognize threatening people and (2) crows can pass this knowledge along to other crows.

In general, on assumption questions, you should prefer more narrowly-worded, "weaker" answers. In other words, you don't want to overshoot your mark of what absolutely must be true in order for the conclusion to be valid.

Answer choice (B) overshoots this mark. There's a probability word that we should pick up on: "always."

Must "crows that perceive an individual as threatening always respond by shrieking and dive-bombing?"

No, not necessarily. Maybe sometimes crows that perceive an individual as threatening do something else instead. Maybe they fly away. Who knows?

The proposition in answer choice (B) is not essential to the validity of the conclusion.

I hope this helps!

[bruceg]

I don't agree answer choice A is necessary. The presence of other crows proves nothing about whether the original crows "passed their concerns on".

Let's say the original crows did NOT pass their knowledge on. Couldn't the new crows attack with the original crows just instinctively, just as they would any new threat they've never encountered or been warned of before?

Let's say the original crows DID pass their knowledge on. Couldn't the original crows attack the scientists out of bottled rage while the other crows who now recognize them as a threat, not be as motivated by rage, and perhaps flee?

So it's not necessary to see other crows attacking to prove the information was passed on. Answer A is illogical.

[bruceg]

Okay, now I see it. We don't need an assumption that PROVES the conclusion, just that SUPPORTS the conclusion a little bit.

B-E are easy to dismiss
B - there could be other ways to respond to threats, as long as dive-bombing is one of them
C - not necessary for OTHER birds to recognize someone as a threat, just other CROWS
D - this just proves crows dive-bomb both strangers and those they recognize as a threat - it weakens the conclusion
E - human faces not even part of the argument

I've argued there may be other reasons crows could dive-bomb the scientists if they don't recognize them, and that these knowledgeable crows may not attack at all. But in order for the scientists to have ANY SUPPORT for their argument that the original crows passed their knowledge on, they have to show the original crows and new crows are behaving similarly toward the scientists.

This doesn't prove their conclusion. And the conclusion may still be true even if the new crows don't attack. But they have NO support if new crows don't attack, but at least SOME support if new crows do attack.


sheesh.

I don't agree answer choice A is necessary. The presence of other crows proves nothing about whether the original crows "passed their concerns on".

Let's say the original crows did NOT pass their knowledge on. Couldn't the new crows attack with the original crows just instinctively, just as they would any new threat they've never encountered or been warned of before?

Let's say the original crows DID pass their knowledge on. Couldn't the original crows attack the scientists out of bottled rage while the other crows who now recognize them as a threat, not be as motivated by rage, and perhaps flee?

So it's not necessary to see other crows attacking to prove the information was passed on. Answer A is illogical.

[Luke Haqq]

Hi bruceg!

But in order for the scientists to have ANY SUPPORT for their argument that the original crows passed their knowledge on, they have to show the original crows and new crows are behaving similarly toward the scientists.

In general, yes, the new crows are key. A claim made in the stimulus is that a given scientific study shows that crows can pass on concerns to other crows. The evidence that follows, however, doesn't lead to this conclusion unless there area at least some new birds in the group years later.

We don't need an assumption that PROVES the conclusion, just that SUPPORTS the conclusion a little bit.

I'd suggest thinking about this differently. What you are describing (something that supports the conclusion even if only a little bit) is the type of answer choice one would be looking for on a strengthen question. This, however, is an assumption question. For that type, the correct answer choice will be some element that is needed for the conclusion to follow.

Remember, there are three types of helper question stems--strengthen, justify, and assumption questions. A correct answer choice for a strengthen question will help the conclusion, in any amount. For a justify question, the correct answer choice is more than enough--it is sufficient--for the conclusion to follow. For an assumption question, the correct answer choice is necessary or required for the conclusion to follow.