Lecture 22: Deductive Reasoning

Question 1

Types of deductive Reasoning Problems

Answer 1

• Quantifier: All, no, some, some not
• Comparative/Relational: A>B>C therefore A>C
• Conditional: If-then statements

Question 2

Validity

Answer 2

Follows the premises

Question 3

Truth

Answer 3

Is not false

Question 4

Conversion

Answer 4

Many mistakes people make are not valid but would be if the premises were adjusted

Question 5

Sound Argument

Answer 5

An argument that is both valid and true

Question 6

Formal rule theories: explanations of errors, theoretical problems

Answer 6

assumes we have a mental logic built in, and we apply those rules to figure out problems
* We make mistakes because premises are misinterpreted or some logical rules are less available than other, or you can’t find a proof
* Problems are that content effects exist and also they assume that our mental architecture has these built in, but we hardly have to do deductive reasoning in real life

Question 7

Mental model theory: explanation of errors, theoretical problems

Answer 7

• The way we reason is we build mental models in which the premises are true and try to find out what else is true
  
  • Based on how many are true we can infer the validity of the problem
• Make mistakes b/c of working memory limitations; can only have so many mental models at once
• Would we really be built with this mechanism in our brain?

Question 8

Verbal reasoning theory: explanation of errors

Answer 8

• Says that we apply language processing to deduce things
• We make mistakes because language is not adapted to the needs of deduction

Question 9

Competence

Answer 9

what people are capable of in principle

Question 10

Principle

Answer 10

what people do in practice

Question 11

Paradox of Rationality

Answer 11

People are bad at solving deductive reasoning, and yet we are rational

Question 12

Valid Rules

Answer 12

• Modus ponens: if A implies B and be is true then A is true
  
  • Modus tollens: opposite ^

Question 13

Invalid rules

Answer 13

• Affirming the consequent: If A implies B then and A is true then B is true
  
  • Denying the antecedent: If A implies B and A is not true then B is false