L21Deduction.6slides - Deductive Reasoning Lecture Outline...

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Unformatted text preview: Deductive Reasoning Lecture Outline Issues: (a) What are the phenomena of deduction? (b) How do people reason deductively? 1. Introduction to deduction – What it is, types of deductive problems 2. Phenomena of deductive reasoning – Syllogistic reasoning: difFculty, validity, content, atmosphere, Fgural, conversion – Wason selection task: difFculty, content 3. Theories of deductive reasoning – ¡ormal rules – Mental models – Verbal reasoning Deductive Reasoning: Examples QuantiFer (Categorical Syllogisms) Some businessmen are wealthy All wealthy people are powerful Therefore some businessmen are powerful Comparative (Linear Syllogisms) Mighty Joe Young is more powerful than Godzilla King Kong is more powerful than Mighty Joe Young Therefore, King Kong is more powerful than Godzilla Conditional If you write a good research proposal, then you will get funded. You write a good research proposal You will be funded Quantifers: Syllogisms All men are animals. Some animals are aggressive Therefore, some men are aggressive All men are animals Some animals are female Therefore, some men are female All A are B Some B are C Therefore, some A are C Quantifer types All doctors are rich. Some lawyers are dishonest. No politician is trustworthy. Some actors are not handsome. DiFfculty EFFect Syllogisms are hard Subjects typically get ~50% wrong Some B are A No C are B What, if anything, necessarily follows? Validity effect Some A ʼ s are B ʼ s All B ʼ s are C ʼ s Therefore, some A ʼ s are C ʼ s (valid) All A ʼ s are B ʼ s Some B ʼ s are C ʼ s Therefore, some A ʼ s are C ʼ s (invalid) more likely to accept valid than invalid All dogs are animals....
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This note was uploaded on 12/26/2009 for the course PSYCH 240 taught by Professor Gehring during the Fall '08 term at University of Michigan.

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L21Deduction.6slides - Deductive Reasoning Lecture Outline...

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