PSC 41 Lecture Notes - Lecture 3: Modus Tollens, Modus Ponens, Gruel
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PSC 41 Full Course Notes
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Inducive: when you reason from a speciic case to general principles: ex. One swan is white > all swans are white. Typically deducive arguments have three statements: if p, then q (condiional if- then statement) Statement about whether p or q is true or not. Consider the statement if something is a fruit, then it contains seeds two valid deducive inferences: modus ponens (airming by airming): if p, then q all fruit contain seeds. P is true- an apple is a fruit. Q is true- therefore, apples contain seeds: modus tollens (denying by denying) If p, then q- all fruit contain seeds. Not q- carrots do not contain seeds. Not p- therefore, carrots are not a fruit. Can"t draw a conclusion by saying not p irst. Two deducive fallacies or errors: denying the antecedent. If p, the q- all fruit contain seeds. Not q- therefore, eggplant do not contain seeds: airming the consequence.
