Question #1564

"no statements"

Started by erica-scott · started 2020-07-31 21:25 · last activity 2020-08-05 15:25 · 3 replies

I am confused on when to use the rules in S&N "no statements": pick a variable and make is sufficient, negate the other and make it necessary. In the video lecture when diagraming out "She knows that no scientist appreciates poetry", she said " S --> not P". But why wouldn't "no scientist be "not S" and then you negate the necessary condition bc it is a "no statement" and then it would be "not P". So originally I got, "not S --> not P". I am really confused on when to use the specific "no terminology" rules and when it is just used to negate a certain claim. Thanks!

Replies

  1. shunhe · 2020-08-01 03:34

    Hi @erica-scott, Thanks for the question! So when we diagram “no” statements, we negate what comes AFTER the no. So what comes after the “no” in “no scientists”? Well, the word “scientists.” And that’s represented as S. So that’s why you would get S —> ~P there. In general, if you’re having troubles with diagramming something, you can always try to translate it from the “if then” conditional you diagram and see if that makes sense with the original meaning of the statement. So for example, no scientist appreciates poetry. The first way you diagrammed it you can read as “if you’re not a scientist, you don’t appreciate poetry.” Is that what “no scientist appreciates poetry” mean? No it’s not. Now try it the other way. If you’re a scientist, you don’t appreciate poetry. That matches up with what “no scientist appreciates poetry” means! And so that’s how we get to know that that’s the correct way to diagram it. Hope this helps! Feel free to ask any other questions that you might have.

  2. erica-scott · 2020-08-01 17:37

    yes! that helped! thanks so much!

  3. shunhe · 2020-08-05 15:25

    Glad I was able to help!

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