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Hey there! Hope everyone is doing well in their LSAT studies!
I stumbled upon a question that stated "otherwise" within the answer choices. (for reference: PT 63 Section 1 #21) J.Y. noted that otherwise means "or, and not both" which is a biconditional, however, I'm having trouble distinguishing this from "not otherwise"
If someone can kindly look over the two statements I have provided below, one with otherwise & the other with not otherwise.
Examples:
If a class involves science work, the class will be conducted in a laboratory; otherwise, it will be conducted in a normal room.
If a class involves science work, the class will be conducted in a laboratory or a normal room, but not otherwise.
Are these both the same in conditional logic? Laboratory (--) Normal room.
Also, would someone be able to provide an example that would likely be a rule on a logic game with those terms?
Thank you!
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3 comments
thank you for your explanation!
Also I do recall seeing a rule in a sequencing game that used the otherwise language.
Those with better memories than I do can probably point out that game.
SW --> L
Otherwise
NOT(SW) --> N
If L and N are your only options (ie Not L = N)
then NOT SW --> Not L (N)
If you combine that with the Contrapositive of the Original you get Not L --> Not SW
And Not SW --> Not L and that is indeed a bi conditional Not L (--) Not SW and the logical Equivalent SW (--) LW
So otherwise just negates the sufficient condition to get you a new necessary condition, it can only become a bi-conditional if Not L = N
SW --> L or N
But not Otherwise:
Not SW --> Not ( L or N) [which is (Not L and Not N)]
Take the contrapositive of the above and you get
N or L --> SW
combine with the first statement and you get your bi conditional
N or L (--) SW
Not Otherwise is indeed a bi-conditional without further assumptions.
I hope that helps