Example 3 in S/N vid tutorial @ 01:50:14 re: elimination of answer option E
Would someone kindly clarify the explanation/rationale for eliminating answer option E, please?
"Every migration is accompanied by rapid advances in civilization."
I take this to mean M -> RAC. However, the instructor diagrams it as M -> II during his explanation of why option E is not the correct answer.
From the initial extraction of the logic from the passage, I get the following along with each of their contrapositives:
DSC -> M
M -> II
RAC -> II
But, I don't understand how the instructor extrapolated M -> II from the statement in option E, "every migration is accompanied by rapid advances in civilization". Further, why/how he arrives at his point "that we don't just reverse" the statement (RAC -> II) to conclude that just b/c there are intermingling ideas there are rapid advances in civilization. I know that we don't just reverse but rather we reverse and negate. What I don't understand is how that translates in application to the language in option E.
Please help!
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You’re correct. (E) can be diagrammed as Migration ? Rapid Advances in Civilization.
He wrote Migration ? Intermingling Ideas to illustrate the trick (E) is trying to play on test-takers. (E) wants to trick test-takers who misdiagrammed the last condition as Intermingling Ideas ? Rapid Advances in Civilization. If that misdiagramming were true, it would combine with Migration ? Intermingling Ideas to form the conclusion of Migration ? Rapid Advances in Civilization. Of course, the last claim should be diagrammed as Rapid Advances in Civilization ? Intermingling Ideas, so (E) is not a valid conclusion.
