The author uses the word "immediacy" (line 39) most likely in order to express
SavannahMon January 8, 2019
Question about missing premises
How do you find the missing premises? I understand how to answer these questions, and understand the sufficient and Necessary rules. But for example if something gives you: (this probably makes no sense but these are the questions I don't know how to answer)
A>not B
Missing
Conclusion- C> not A
How do you go about answering these? What are the steps to finding the correct answer? Do you need to do the contrapositive and the answer will pop out? I just have no idea how to approach problems such as these
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Great question! It's great that you're feeling comfortable with S + N rules—that's a good sign that you'll soon be able to conquer these questions as well.
In going about answering these questions, it often helps to do the contrapositives of the given statements so that you can easily see how everything can link up. While you don't always have to do the contrapositive for each given statement, it often helps. In the example you give, it helps A LOT.
A - >not B
Missing
C: C - ->not A
Taking the contrapositive of the first premise, we have B - -> not A
How can B - ->not A plus another premise make the conclusion that C - ->not A?
What if C - ->B? We need to bring in the variable C so that it's in the premise as well, and we need it to connect to the other premise so we can have a conclusion that makes sense.
If C - >B, and B - ->not A, we have the chain
C - ->B - ->not A
From this, we can conclude that C - ->not A
Does this help? Do you see how taking the contrapositive of the premise helped us see more clearly how to link up the statements together to find what was missing?
Let us know if you have any additional questions!
SavannahMon January 8, 2019
It helps a little bit, would you do the same thing in order to find the conclusion as well?
Ravion January 13, 2019
@Savannah, where else are you getting stuck? Let us know, and we'll be happy to explain it in a different way so that it clicks.
Yes, using this strategy to find the conclusion works well also. The key is to have all of the information arranged in a manner where you can easily see how the different conditional statements can link up to each other to form a train that connects everything up.
