#16 - Researcher: Dinosaurs lack turbinates—nasal cavity

[Administrator]

Complete Question Explanation

Method- Argument Part. The correct answer choice is (B).

Answer choice (A):

Answer choice (B): This is the correct answer choice.

Answer choice (C):

Answer choice (D):

Answer choice (E):

This explanation is still in progress. Please post any questions below!

[165OrBust]

Hello PS Team,

These Method - AP questions are really taking their toll on my scores! I’m hoping you can help me understand this question correctly and nudge me back on track.

I broke down the argument as follows:

Premise (fact): Dinosaurs lack turbinates.
Premise (claim): Some pleobiologists argue this implies that all dinosaurs were cold-blooded. (Note: “some say...” - expect conclusion to disagree)
Premise (leading to intermediate conclusion): Some dinosaur species lived in Australia and Alaska.
Intermediate conclusion (directly supporting conclusion): Only warm-blooded animals could survive such temperatures.
Conclusion (refuting claim): These paleobiologists are mistaken.

After staring at my analysis for a few minutes, I can only conclude that I erroneously categorized “only warm-blooded animals...” as an intermediate conclusion, and that it is rather a second premise which follows “some lived in a Australia and Alaska” and directly supports the conclusion.

Am I missing a key indicator that clearly shows that “only warm-blooded animals” is not an intermediate conclusion?

Thanks for your advice!
Liz

[Robert Carroll]

Liz,

If that statement were an intermediate conclusion, it would have to be based on something. But that statement stands alone. There's no justification for why an animal would have to be warm-blooded to survive a certain climate. So that's not an intermediate conclusion. Instead, consider how the statement is used, because this is a common argument form. It's a conditional: survive temps warm-blooded The statement before that affirms that certain creatures have survived in such an environment. This combination is used to demonstrate that the necessary condition of the conditional is true. Generalizing, in any case where there's a conditional and a statement of the truth of the sufficient condition, those two things can't be related to each other as premise to intermediate conclusion (though there's no reason they couldn't be related to other things in that way). A B, A, therefore B is the basic idea; the conditional and the affirmation of the sufficient condition have to be presented as separate premises, and their combination leads to something else. So in this case, the premise about Australia and Alaska doesn't lead to the conditional, but functions in combination with the conditional to lead to a conclusion.

Robert Carroll

[165OrBust]

Thank you Robert!

Your comments completely cleared things up and made me realize my rookie mistake. Also, framing it as part of a conditional argument really drove the lesson home.

Perhaps it’s time for a day off to recharge!

Many thanks,
Liz

[Dancingbambarina]

Thanks for clearing all up Robert. You are also astoundingly good at laying things out articulately and in a congestible manner.

[dshen123]

why is it not C?

[Jeff Wren]

Hi dshen,

There's really two problems with Answer C.

The biggest problem is the second half of the answer, "the paleobiologists' assertion that dinosaurs lack turbinates." The paleobiologists' assertion in this argument isn't that dinosaurs lack turbinates. That dinosaurs lack turbinates is stated as a fact in this argument, and the researcher making this argument does not dispute this fact. Instead the assertion that the paleobiologists make (that the researcher does dispute) is that "all dinosaurs are cold blooded."

The conclusion of this argument, "These paleobiologists must be mistaken" refers to them being mistaken about their belief that "all dinosaurs are cold blooded," not about the fact that dinosaurs lack turbinates, which isn't in dispute.

The other issue with Answer C is that the statement "only warm-blooded animals could survive such temperatures" isn't really counterevidence in-and-of itself. Counterevidence is evidence that directly contradicts another claim. For example, to disprove the statement "all apples are red," showing a green apple would be counterevidence to that claim.

Here, the statement "only warm-blooded animals could survive such temperatures" doesn't contradict/counter anything by itself, not even the paleobiologists' assertion that "all dinosaurs are cold blooded." Instead, this statement needs to be combined with the other premise regarding dinosaurs in Australia and Alaska in order to support the conclusion that "these paleobiologists must be mistaken."

[Dancingbambarina]

Would the line in the stem be counterevience to the implication in the stimulus that all dinosaurs were cold-blooded?I think so, since we have acknowldeged that:

The other issue with Answer C is that the statement "only warm-blooded animals could survive such temperatures" isn't really counterevidence in-and-of itself. Counterevidence is evidence that directly contradicts another claim. For example, to disprove the statement "all apples are red," showing a green apple would be counterevidence to that claim.

Thank you

[Dana D]

Hey Dancing,

What line in the stem are you referring to that is counterevidence?

Just to reiterate Jeff's point - even if there was 'counterevidence' here, answer choice (C) would be incorrect because it would not be countervidence "to the paleobiologists’ assertion that dinosaurs lack turbinates." We can't ignore parts of the answer choices we don't like. This second half of the answer choice is completely counter to the stimulus, so this answer choice is incorrect.