Law School Discussion

TM hw help

TM hw help
« on: July 23, 2005, 08:41:58 PM »
lesson two page 21

p: some a's re b's
p: either all a's are 's or no a's are 's
c: ?

answer
all a's are b's

why is that the right answer, can someone please explain thanks

Re: TM hw help
« Reply #1 on: July 23, 2005, 09:21:11 PM »
I dont know if this is diagrammable but if you think about the fact one of the premises state that A --> B or A --> ~B.  One or the other has to be true...both can't be true because that wouldn't make sense.  Another of the premises state that some of the A's are B's, so that means that it can't be true that A --> ~B.  If no a's are b's, then there's no way some a's could be b's.  That wouldn't make sense either.  So therefore, based on the premise A--> B, all A's have to be B's. 

If you use an example like some cars in a parking lot are red, and we know that either all cars in the parking lot have to be red or no cars in the parking lot are red.  So if some of the cars in the parking lot are red, then the conclusion is that all cars in the parking lot have to be red.