Conditional Reasoning Clarification

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Conditional Reasoning Clarification

Postby obsrvr » Mon Mar 25, 2013 5:02 pm

Example from CR chapter of LR bible.

"It is either feast or famine. "

Fe = feast Fa = famine

Fe --> ~Fa
Fa --> ~Fe

~Fe --> Fa
~Fa --> Fe

Question: Can the above relationship be summarized into Fe < | > Fa, and in if so, would it mean the same thing as diagrams above or are these equivalent? I am just a little confused by all these arrow diagramming.

Thanks for help.

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Power Clean

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Joined: Sat Dec 01, 2012 12:35 am

Re: Conditional Reasoning Clarification

Postby Power Clean » Wed Mar 27, 2013 12:01 pm

obsrvr wrote:Fe --> ~Fa
Fa --> ~Fe

~Fe --> Fa
~Fa --> Fe

The first set can be condensed into Fe<-|->Fa. This set of conditional statements is the result of the conditions in this "either or" being opposites, meaning that not only is it X or Y but NOT BOTH. Both can never occur simultaneously, and that's what this dual option is saying.

However, the second set, which covers the either or aspect, is NOT encompassed by the double not arrow. This set captures the meaning of either or, because as soon as you don't have one (the sufficient condition of each), you necessarily must have the other.

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