Deduktiv reasoning

Deduktiv reasoning

1. Garantee the conclusion if premises are true

   • How to recognize deductive argument?
     • Se the form of the argument
       • "truth-functional statments" - sannhetspåstander
         • Enkelt premiss inneholder en påstand Komplisert premiss inneholder flere påstander
         • Logical operators - de som beskriver sannhetsrelasjonen til påstandene
           • NOT p (Negation)
           • IF p THEN q (implication)
           • p OR q (Disjunction)
           • p AND q (Conjunction)
       • Four commen forms:
         • Affirming the antecedent
           • P1: If p, then q | P2: p | C: q
             • Pass på fallaci: Denying the antecedent: If p then q | Not p | Therfore not q
         • Denying the consequent
           • P1: If p, then q | P2: not q | C: not p
             • Pass på fallacy: Affirming the consequent: If p then q | q | therfore p
         • Chain argument
           • P1: If p, then q | P2: If q, then r | C: If p, then r
         • Disjuntive syllogism
           • P1: Either p or q | P2: Not p | C: q
   • Because the conclution is implied in the premises