Although all birds have feathers and all birds have wings, some birds do not fly. For example, penguins and ostriches...

Victoria on May 12, 2020

Hi @fable,

The wording is a bit tricky, but answer choice (B) actually says that all chairs have: (1) a seat; and (2) some support.

Therefore:

Chairs --> Seat

Chairs --> Some support

The answer choice then provides us with two examples: (1) decorative chairs; and (2) lion-taming chairs. These examples show us that some chairs or not used for sitting.

Chairs - some - not sitting

This parallels the reasoning in the passage:

Birds --> Feathers

Birds --> Wings

Two examples: (1) penguins swimming; and (2) ostriches running. These examples show us that some birds do not use their wings for flying.

Birds - some - not flying

Hope this is helpful! Please let us know if you have any further questions.

fable on May 13, 2020

I'm still confused, I understand what you said and I drew that same sketch to explain the quantifies and and S/N. Again my problem with this answer choice is the second some. Chairs ---> some support. The passage did not some in the Necessary. It is Birds ---> feathers. And birds ---> wings, not birds ---> some wings.

LeeLarue on May 31, 2020

@fable, this is how I broke the stimulus & answer choose B) down:

"All birds have feathers" ||. "All chairs have a seat"
B -> F. ||. C -> Seat

"All birds have wings" ||. "All chairs have SOME support" - here "some support" is NOT used as a quantifier but to TRICK you.
B -> W. ||. C -> SS

"Some birds don't fly". ||. "Not all chairs are used for sitting" - is in the quantifies lesson at the part when Mehran is explaining ALL
B -some- ~F. ||. C -some- ~S

And then the two examples penguins (birds) that don't fly (swim) & ostriches (birds) that don't fly (run) vs. chairs for (decoration) not sitting) & chairs for (taming lions) not sitting

Looks like this

(Penguins) B -some- ~F (swim) vs C (chairs) -some- ~S (for decorations)
(Ostriches) B -some- ~F (run) vs C ( chairs) -some - ~S (for taming lions)

Hope that helps.

mstabilej on October 6 at 06:43PM

@LeeLarue Thank you for explaining how the second "some" is not used as a quantifier here.

That said, I had been eliminating answer choices that used inconsistent quantifiers at the very start of the sentence, for example. In other words, if the first sentence of a stimulus said "All cars" but one of the answer choices said "Some monkeys", I would not even proceed to read the rest of the answer choice.

Is this incorrect? It appears as though this question demonstrates that if there is more than one quantifier in the stimulus (ALL and SOME for example), as long as both of those specific quantifiers appear SOMEWHERE in an answer choice, it can't be eliminated right away. In other words, the quantifiers can be rearranged within the answer choices it seems. I didn't think this was possible.

Emil-Kunkin on October 7 at 03:55PM

I would recommend not using that approach. While it can be helpful in arguments that are really just a mechanistic sufficient and necessary argument (e.g., all a are b, all be are c, Jim in and A, so Jim is a C), I think in any argument more complex than that it could lead you astray for two reasons. First, quantifiers can show up in unexpected ways as we see here. Second, the order of the premises and conclusion could change. The first sentence of the passage is not necessarily akin to the first sentence of the right answer, its totally kosher for the right answer to open with the conclusion even if the conclusion was the last sentence of the passage.

mstabilej on October 8 at 12:06AM

Thank you, that answers my question. I think I have gotten a lot of these incorrect because I didn't realize that the conclusion didn't have to be in the same location within the answer choices as it had been in the stimulus.

Emil-Kunkin on October 9 at 12:55AM

Yeah that's a pretty important thing but an extremely easy mistake to make! It's one of those little things that seems simple in retrospect but deeply difficult when you're in the thick of it. I would take this a step further in the sense that it is important to focus on the structure of the logic in the argument, and that what matters are the ideas expressed rather than the specific word choice.