I have come across an issue with these because I am underuse where the "not" is supposed to be.
Take the following example:
P1: A -> Not B
P2: ?
C: B -> C
The correct answer for premise 2 is: Not A -> C with the Contrastive being Not C -> A
But I put down the following:
A -> Not C with the contrapositive being C -> Not A
I want to know how to differentiate between what variable the not should be put or does this not matter?
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It does matter which variable is negated, because the answer that you first provided does not lead to the conclusion. Let's test it.
P1: A - > not B P2: A - > not C or C - > not A C: B - > C
Ok, the conclusion gives us B. From premise 1, we get not A. This is what we need to use to get to the conclusion. With the premise 2 that you provided, not A does not lead to the conclusion. It does not guarantee C.
Here is how we need to approach this problem.
P1: A - > not B P2: ? C: B - > C
The conclusion gives us B. From premise 1, we get not A. How can we say that not A leads to C? We can simply write:
not A - > C or not C - > A
With the correct answer, not A is sufficient for C. This means that it guarantees the conclusion is properly drawn.
With your previous answer, not A is necessary for C. It does not guarantee the conclusion.
