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Negation Rules

Negation Rules. Reductio Ad Adsurdum Indirect Proof Dash In and Dash Out. Negation Rules. Reductio Ad Adsurdum Indirect Proof Dash In and Dash Out The basic idea: To prove A, Assume -A and derive a contradiction. Since -A leads to a contradiction, -A must be wrong,

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Negation Rules

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  1. Negation Rules Reductio Ad Adsurdum Indirect Proof Dash In and Dash Out

  2. Negation Rules Reductio Ad Adsurdum Indirect Proof Dash In and Dash Out The basic idea: To prove A, Assume -A and derive a contradiction. Since -A leads to a contradiction, -A must be wrong, and so A must be right.

  3. Negation Rules Dash In and Dash Out An illustration: Eat your SPINACH. Why? Because if you don’t you won’t get DESERT.

  4. Negation Rules Dash In and Dash Out An illustration: Eat your SPINACH. Why? Because if you don’t you won’t get DESERT. -S>-D The parent hopes the child will conclude: S

  5. Negation Rules Dash In and Dash Out Eat your SPINACH. Why? Because if you don’t you won’t get DESERT. D A -S>-D A S

  6. Negation Rules Dash In and Dash Out Eat your SPINACH. Why? Because if you don’t you won’t get DESERT. D A -S>-D A -S PA S Child’s Fantasy

  7. Negation Rules Dash In and Dash Out Eat your SPINACH. Why? Because if you don’t you won’t get DESERT. D A -S>-D A -S PA -D >O D&-D &I S Child’s Fantasy

  8. Negation Rules Dash In and Dash Out Eat your SPINACH. Why? Because if you don’t you won’t get DESERT. D A -S>-D A -S PA -D >O D&-D &I S Contradiction! So S is the only choice.

  9. Negation Rules Eat your SPINACH. Why? Because if you don’t you won’t get DESERT. 1 1. D A 2 2. -S>-D A 3 3. -S PA 2,3 4. -D 2,3 >O 1,2,3 5. D&-D 1,4 &I 1,2 6. S 3-5 -O An Official Proof

  10. Negation Rules Eat your SPINACH. Why? Because if you don’t you won’t get DESERT. 1 1. D A 2 2. -S>-D A 3 3. -S PA 2,3 4. -D 2,3 >O 1,2,3 5. D&-D 1,4 &I 1,2 6. S 3-5 -O An Official Proof

  11. Negation Rules A PA : ?&-? -A -In -A PA : ?&-? A -Out -In and -Out a.k.a. Reductio Ad Adsurdum or Indirect Proof To prove a statement, assume the opposite and derive a standard contradiction: a statement of the form ?&-?

  12. Avoiding a Confusion A PA : ?&-? -A -In -A PA : ?&-? A -Out -In and -Out a.k.a. Reductio Ad Adsurdum or Indirect Proof Indirect Proof reasoning often confuses people.

  13. Avoiding a Confusion G = My client is guilty P = My client was in Paris. G>P The crime was in Paris -P A witness saw him in Houston G PA P >O P&-P &I -G -In

  14. Avoiding a Confusion G = My client is guilty P = My client was in Paris. G>P The crime was in Paris -P A witness saw him in Houston G PA P >O P&-P &I -G -In Sleepy Juror: The defense said: ‘Suppose my client is guilty’. So even his own lawyer thinks he is guilty.

  15. Avoiding a Confusion G = My client is guilty P = My client was in Paris. G>P The crime was in Paris -P A witness saw him in Houston G PA P >O P&-P &I -G -In How to present an Indirect Proof in Court.

  16. Avoiding a Confusion G = My client is guilty P = My client was in Paris. G>P The crime was in Paris -P A witness saw him in Houston G PA P >O P&-P &I -G -In How to present an Indirect Proof in Court: Give the PA to your opponent.

  17. Avoiding a Confusion A PA : ?&-? -A -In -A PA : ?&-? A -Out -In and -Out a.k.a. Reductio Ad Adsurdum or Indirect Proof To prove a statement, assume the opposite and derive a standard contradiction: ?&-?. For more click here

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