"Nobody dances sober, unless they happen to be insane." – H.P. Lovecraft

Lamont March 4, 2022

The rules of Unless Statements

Based on the steps the statement following the word unless is the necessary condition. then step 2 says negate the other part and make it the sufficient condition. So I diagramed it per the rules. not DS --->I not I------>DS (contrapositive) Please tell me where did I make the mistake?

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Emil-Kunkin March 5, 2022

Hi Lamont,

Our statement is that "nobody DS unless I"

We could rewrite this as "Not DS unless I"

Using the rules for unless, we make the I the necessary condition, and the Not DS the sufficient condition that we then negate. This leaves us with

Emil-Kunkin March 5, 2022

Sorry @lamont, my last message got cut off. This leaves us with

If DS -> I,

And it's contrapositive

If Not I -> Not DS

Emil-Kunkin March 5, 2022

I think your mistake was that you didn't negate the negative in the sufficient condition. That is, you treated the sufficient as "DS" rather than "Not DS"

Lamont March 11, 2022

Thank you, I didn't negate. Sometimes when I am working on these drills I'm trying to commit to memory the rules I lose focus. I think I'm going to have to use index cards to help me remember the rules. Again thank you.