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Unformatted text preview: A D D Therefore: A Argument form: p q q therefore: p (specific argument) Could also be: p q therefore: r Argument invalid because its argument form is invalid Truth table to test validity/invalidity p q p q T T T T F F F T T F F T Conclusion P2 P1 Line 3 makes argument invalid It has two true premises and a false conclusion!! Pay attention to what is the premises and what is the conclusion All it takes is one invalid interpretation (one of the substitution instances) to make the entire thing corrupt When it is a valid argument form, anything with that specific substitution instance will be a valid argument For example: p q p therefore:q is a valid argument form P p q q T T T T F F F T T F F T P1 P2 Conclusion Only invalid when it has two true premises and a false conclusion, not any other way!!!!...
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- Fall '07
- Logic, Argument form