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 PB410
  • Posts: 39
  • Joined: Apr 01, 2017
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#37706
Hi,

I'm not entirely sure why answer choice A is wrong.
I setup the stimulus to be
FPW-----> H and LC
and
(no)H or (no)LC----->FP(is not)W

is A wrong because it is dealing with a different sufficient condition than the one in the stimulus, because Ann kept her promise? I'm kind of struggling to understand the shift from Failure to keep a promise as a condition to someone who kept a promise as a condition.

D is set up as (no)H and (no)LC----->FP(no)W, which is an accurate contrapositive.
 Eric Ockert
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#37721
I think you hit the nail right on the head with the problem on answer (A). It's about keeping a promise rather than failing to keep a promise. Rethink this rule in the stimulus as just a rule ABOUT failed promises. Try this diagram:

Wrong :arrow: Hurt + Lose Confidence

And the contrapositive:

not Hurt OR not Lose Confidence :arrow: not Wrong

So answer (D) hits BOTH of the sufficient conditions in the contrapositive above (it only needed to hit one OR the other) and thus shows that the failure to keep a promise was not Wrong. Bingo.

Answer (A) falls outside the scope of the rule in the stimulus and so we really have no idea whether Ann's kept promise is wrong or not.

Hope that helps!
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 yenisey
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#96290
Why answer choice "C" is wrong?
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 katehos
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#96388
Hi yenisey!

If we diagram the principle contained within the stimulus, we get a diagram that looks like this:

Wrong :arrow: Harm & Lose Confidence
Harm or Lose Confidence :arrow: Wrong

This is the diagram we will use to find the correct answer choice! Looking at answer choice (C), we see a line of logic like this:
     Premise - George made a promise to Reiko
     Premise - George did not keep his promise to Reiko
     Premise - Reiko was hurt financially as a result
     Conclusion - Reiko financially hurt :arrow: George's failure to keep a promise was Wrong

Comparing this line of reasoning to our diagram, we can see that in it would be a Mistaken Reversal to conclude George is wrong because Reiko was hurt. Remember, the (plus this answer choice does not mention losing confidence, but, regardless, the MR is enough reason to eliminate (C) as a contender). Remember, presence of a necessary condition does not guarantee the existence of the sufficient!

I hope this helps :)
Kate
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 sensei
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#108424
Just a general formatting question here, I understand that D is the right answer as the contrapositive of our Formal Logic Statement.
I want to make sure the way I am posing my formal logic is correct, here's what I have:

As a rule about broken promises
Hurt and Lost Confidence --> Wrong
If ^ then^

is this format correct? I just don't want to have this wrong and mess up a question as a result. Thank you!!
 Luke Haqq
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#108672
Hi sensei!

Your diagram is close, but the correct way to diagram it is slightly different. For the correct way to diagram it, take a look at the post by katehos immediately before your post or the earlier one by Eric. They both diagram it the same, although the formatting is slightly different.

Note that in both cases, they don't have "wrong" as a necessary condition. Wrong only occurs as a sufficient condition--if failing to keep a promise is wrong, then this must be because it harms the one to whom the promise is made and it also causes people who discover the failure to lose confidence in the person's ability to keep promises. Stated another way, if a failure to keep a promise does not harm the one to whom it is made or it does not cause those who discover the failure to lose confidence in the person's ability to keep promises, then it is not wrong. Note that the second way of phrasing it is the contrapositive of the first. In neither case does wrong occur as a necessary condition.

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