Contrapositive arguments

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Contrapositive arguments

by waltz2salsa » Wed Oct 20, 2010 9:25 am
Odysseus answered well when the priests showed him a picture of those who had honored the gods and then escaped shipwreck, and asked him whether he did not now acknowledge the power of the gods-"Yes," he asked, "but where are those pictured who were drowned after their prayers?" And such is the way of all superstitions; wherein humans, having a delight in such vanities, mark the events where they are fulfilled, but where they fail, though this happens much oftener, neglect and pass them by.

Which one of the following contains the error of reasoning described by the author in the passage?

(A) I have discovered that Friday the 13th really is a day of misfortune. Just this past Friday, the 13th, I locked myself out of the house.
(B) Although Napoleon and Alexander the Great were short, Abraham Lincoln and Charles de Gaulle were tall. So short people seek leadership in order to overcome feelings of inferiority.
(C) Every semester for the past 15 years, an average of 10 percent of Ms. Elliot's history students have dropped her course before the exam. So, it seems likely that we can expect 10 percent to drop out this year.
(D) No reliable observer has ever actually seen a yeti. The strongest evidence seems to be some suspicious tracks. So I think this search for a yeti is probably a wild-goose chase.
(E) I cannot trust my lucky shirt any longer. I wore it to the game today and our team lost.

OA : A

Can someone please help because though it has been discussed in this forum before but the answer has been unsatisfactory

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by David@VeritasPrep » Wed Oct 20, 2010 4:32 pm
What an odd question - certainly not an official one. Anyone who does this should think of it as stretching your logical powers a little -- rather than directly studying for the test.

What you are looking for is a principle or general statement in the stimulus that is then illustrated in the answer choice. The principle in the stimulus is this:

"We notice when predictions come true (or coincidences happen) more often because we are looking for them. When these things do not happen they are not noticed."

So, for example, if you are looking for Friday the 13th to be unlucky then you will notice anytime that it is. That makes choice "A" the correct illustration of the principle. We have one example of the day being unlucky and the conclusion is that it really is a day of misfortune.

Does that answer your question on this one?
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