Deductive Reasoning and Decision Making

Deductive Reasoning and Decision Making Notes

Introduction

• Deductive reasoning: Involves deriving specific conclusions from general premises using principles of logic.
• Decision making: The process of assessing and choosing among several alternatives.

Key Concepts in Deductive Reasoning

• Types of Reasoning:
  • Conditional reasoning (propositional reasoning): Examines relationships between conditions expressed in "if…then…" statements, judged as valid or invalid.
  • Syllogism: Involves two true premises and a conclusion. Examples: "All, none, some…" Accessed as valid, invalid, or indeterminate.

Examples of Deductive Reasoning

• If today is not Friday, then we will not have a quiz today. We will not have a quiz today. Therefore, today is not Friday.
• If an object is red, then it is rectangular. This object is not rectangular. Therefore, it is not red.
• If a feather is thrown at a window, the window will break. A feather is thrown at a window. Therefore, the window will break.

Overview of Conditional Reasoning

• Four types of Conditional Reasoning (Table 12.1):
  1. Affirming the Antecedent (valid): This is an apple; therefore, this is a fruit.
  2. Affirming the Consequent (invalid): This is a fruit; therefore, this is an apple.
  3. Denying the Antecedent (invalid): This is not an apple; therefore, this is not a fruit.
  4. Denying the Consequent (valid): This is not a fruit; therefore, this is not an apple.

Common Errors in Deductive Reasoning

• Affirming the Consequent: Often leads to errors; may seem correct based on real-life examples but does not adhere strictly to logical principles.
• Difficulties with Negative Information: Individuals take longer and make more errors when evaluating reasoning involving negations. Offers examples: "It was not uninteresting" vs. direct questions.
• Abstract vs. Concrete Problems: People generally perform better on concrete examples compared to abstract problems.

The Belief-Bias Effect

• Definition: The tendency to rely on background knowledge and prior beliefs rather than logical rules; leads to frequent errors when logic contradicts personal beliefs.
• Relevance: Highlights importance in understanding intelligence and flexible thinking.

Confirmation Bias in Deductive Reasoning

• Confirmation Bias: People prefer to seek evidence supporting their hypotheses rather than disproving them.
• Wason Selection Task Variations: Examples from social situations like drinking age illustrate how context impacts reasoning strategies and the presence of confirmation bias.

Practical Applications and Examples

• Wason Selection Task: A scenario regarding a rule that requires participants to determine which cards to turn over to validate or invalidate a given conditional statement. Participants show a preference for affirming conditions that align with their hypothesis instead of testing contradictory possibilities.
• Concrete Situations: Participants perform better when reasoning conditions are linked to real-life scenarios, indicating that relatability enhances understanding and accuracy in deductive reasoning tasks.

Closing Thoughts

• Deductive reasoning is a critical skill in decision making that requires practice and understanding of logical principles and cognitive biases affecting reasoning processes. Understanding these frameworks allows for improved logical reasoning and decision-making skills in real-world applications.