Unless the residents of Glen Hills band together, the proposal to rezone that city will be approved. If it is the cit...
180November 5, 2013
Confused by the video
Good evening I am confused on this question because as I have studied hard on the flash cards concerning sufficient and necessary condition key indicators, during the commencement of the passage the instructor uses band together (BT) as the sufficient condition when it should have been the necessary condition and the proposal (P) negated should have been the sufficient condition. The flash cards exactingly and unequivocally indicates unless exclusively introduces a necessary condition and the other portion of the passage is your sufficient which must then become negated. To me this principle was not followed am I correct or am I missing something please help me understand the concept thank you in advance for your assistance.
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The first statement reads: "Unless the residents of Glen Hills band together, the proposal to rezone that city will be approved." You are correct that an "unless" introduces a necessary condition and the other part of the sentence is negated to become your sufficient condition. The correct diagram is:
not A ==> BT
not BT ==> A
As you can see the video writes out just that, however, in reverse order. You still have not A ==> BT, it's merely the contrapositive in the video lesson.
As long as you always write out your principle rule and contrapositive, it technically doesn't matter which you label your principle rule and which you label your contrapositive as they are essentially saying the same thing.
Sorry for the confusion!
Hope that was helpful. Let me know if you have any other questions!
