All intelligent people are nearsighted. I am very nearsighted. So I must be a genius.Which one of the following exhib...

LH44 on March 2, 2019

Please Explain

Hello, can you please explain why D is the correct answer and why C is incorrect? Thank you!!

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Jacob-R on March 3, 2019

Hi @LH44,

I’m happy to help. In order to understand what D is right and C is wrong, let’s first make sure we understand the question stem. We are trying to find the answer that exhibits both of the logical flaws in the argument.

Notice right away that the question says “both” flaws, so can we first glean what each of those flaws are?

We have:

IP -> N
I’m very N.
= I’m G.

Do you see both errors? The conclusion is wrong because it gets the conditional relationship wrong (premise 1 was IP -> N, so if we had I’m an intelligent person as our second premise, we could have gotten to the conclusion N.)

But notice the conclusion is also wrong because it assumes that an increase of one quality — nearsightedness — also means there will be an increase in the other quality — intelligence, even though all we knew from premise 1 is that intelligent people are nearsighted, and nothing about the intensity of either quality!

D is the correct answer because it repeats both of these logical flaws, albeit in a different order in an attempt to confuse you. If we rearrange its clauses, we can see the same logical flaws:

TP -> H
J is extremely H
= J is ET.

C, in contrast, has the following logical premises and conclusions:

P -> 4L
S has 8L*
= S is 2x P.

I see why this answer could be appealing, as it is close in form to the original question. But it is not the best answer both because the premise I’ve marked with * is not as close to “very nearsighted” as answer D’Souza “extremely happy” was, because here we are getting a specific numerical quantity of legs — 8 rather than 4. Answer D was closer because it precisely matched the increase in the degree of the condition, rather than listing a specific number.

I hope this helps! Please let us know if you have further questions.