Question seems like a valid contrapostive statement
Started by
izyat
· started 2019-06-21 07:28
· last activity 2019-07-11 05:49
· 2 replies
When I tried to solve this question, I seemed to find that it had a valid contrapositive argument, but the question says it is flawed. Would it be possible to get an explanation for why it is flawed?
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tylermtakeshita
· 2019-07-11 02:31
I had the same issue. Notice in the first sentence, the "If" indicating the sufficient condition comes before "April rainfall exceeds 5 centimeters". This means that "trees always blossom would be the necessary condition instead of the sufficient as I (and I think you must have) originally diagrammed it.
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Ravi
· 2019-07-11 05:49
@izyat and @noname,
Happy to help. Let's take a look.
Here's how we can diagram the stimulus:
ARE5 - >TAB
ARE5 - >RFM1
/RFM1
Therefore, /TAB
This is not a valid contrapositive. The argument's structure is
A - >B
A - >C
not C
Therefore, not B
This is incorrect. with /RFM1, we can conclude that /ARE5 (the failure
of the sufficient condition). However, for the rule
ARE5 - >TAB, if the sufficient condition is failed, we cannot conclude
/TAB, which is what the argument mistakenly concludes. This is why the
argument is flawed.
We see the same type of flaw in (A)
GP - >SF
GP - >PBS
/PBS
Therefore, /SF
A - >B
A - >C
not C
Therefore, not B
Sure, /PBS invokes /GP, but /GP does not invoke /SF.
Does this make sense? Let us know if you have any other questions!
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