Chapter 12 Deductive Reasoning Flashcards
Deductive reasoning
Given some specific premises, judge whether those premises allow you to draw a particular conclusion based on the principles of logic
Conditional/propositional reasoning task
Describes the relantionship between conditions;
If… then…; judged as valid or invalid
Syllogism
Two statements that we must assume to be true, plus a conclusion
Propositional calculus
A system from categorizing the four kinds of reasoning used in analyzing propositions/statements
Antecedent
The first proposition or statement; the antecedent is contained in the “if…” part of the sentence
Consequent
The proposition contained in the “then…” part of the sentence
Affirming the antecedent
Means that you say the if part of the sentence is true the kind of reasoning leads to a valid or correct conclusion
The fallacy of affirming the consequent
You say the then part of the sentence is true. This kind of reasoning leads to an invalid conclusion
The fallacy of denying the antecedent
You say the if part of the sentence is false. Denying the antecedent also leads to an invalid conclusion
Denying the consequent
You say the then part of the sentence is false. This kind of reasoning leads to a current conclusion
Dual-process theory
Type 1 processing- fast and automatic
Type 2 processing- slow and controlled
Applies to both deductive reasoning and decision making
Difficulties with Linguistically Negative Information
People take longer to evaluate problems that contain linguistically negative information.
People are more likely to make errors on these problems.
causes working memory strain, especially when denying the antecedent or denying the consequent
leads to frequent errors when translating the statement into more accessible, linguistically positive forms
Difficulties with Abstract Reasoning Problems
People are more accurate when they solve reasoning problems that use concrete examples rather than abstract, theoretical examples.
diagrams can be helpful
Everyday knowledge may override the principles of logic.
Belief-Bias Effect
When people make judgments based on prior beliefs and general knowledge, rather then on the rules of logic
Confirmation bias
People tend to try to confirm or support a hypothesis rather than try to disprove it
people are eager to affirm the antecedent, but reluctant to deny the consequent by searching for counterexamples.
The Confirmation Bias
Concrete Versions of the Wason Selection Task
replace numbers and letters with concrete situations from everyday life
People perform much better when the task is concrete, familiar, and realistic.
Griggs and Cox (1982)—drinking age example
Performance improved when task implies a social contract.
The Confirmation Bias
Applications in Medicine
People seek confirming evidence when self- diagnosing disorders (e.g., insomnia).
Both medical students and psychiatrists tend to select information consistent with their original diagnosis rather than investigate information that might be consistent with another diagnosis.
Decision making
assessing and choosing among
several alternatives
no clear-cut rules
no “correct” decision
we often rely on heuristics
Kahneman and Tversky
proposed that a small number of heuristics guide human decision making
The same strategies that normally guide us toward the correct decision may sometimes lead us astray.
small-sample fallacy
We assume a small small will be representative of the population from which it was selected
Representative heuristic
We judge that a sample is likely if it is similar to the population form which this sample was selected for
Base rate
How often an item occurs in the population
Base for fallacy
Emphasizing the representativeness and understanding of-emphasizing important information about base rates
Base Rate and Representativeness
Kahneman and Tversky (1973)
Demonstrated that people rely on representativeness when asked to judge category membership.
even when provided with base-rate information, people tend to ignore it
stereotypes
