Deductive and Inductive Reasoning, Patterns of Development, and Logical Fallacies

Deductive Reasoning

  • Definition: Moves from a general premise to a specific conclusion.

  • Syllogism parts:

    • Major premise (general statement)

    • Minor premise (specific statement)

    • Conclusion (drawn from premises)

  • Validity: Conclusion must logically follow from true premises.

  • Example of valid syllogism:

    • Major: "Exercise contributes to good health."

    • Minor: "Yoga is a type of exercise."

    • Conclusion: "Yoga contributes to good health."

  • Invalid Example: "All dogs are animals. All cats are animals. Therefore, all dogs are cats."

Inductive Reasoning

  • Definition: Moves from specific evidence to a general conclusion.

  • Requirements:

    • Include all relevant evidence.

    • Conclusion fits the evidence better than alternatives.

  • Steps in Induction:

    • Formulate a question/hypothesis.

    • Gather relevant evidence.

    • Infer conclusions from evidence.

Patterns of Development

  1. Compare and Contrast

    • Purpose: Examine similarities and differences.

    • Key words: similarly, in contrast.

  2. Cause and Effect (or Problem–Solution)

    • Purpose: Show connections between actions and outcomes.

    • Key words: because, as a result.

  3. Process Analysis

    • Purpose: Clarify sequences or instructions.

    • Key words: first, next, finally.

  4. Definition

    • Purpose: Clarify complex ideas.

    • Key words: means, refers to.

  5. Description

    • Purpose: Create vivid imagery.

    • Key words: sensory details.

  6. Exemplification

    • Purpose: Provide evidence through examples.

    • Key words: for example, such as.

  7. Narration

    • Purpose: Engage through storytelling.

    • Key words: first-person, plot.

  8. Classification and Division

    • Purpose: Organize items into categories or dissect concepts.

    • Key words: types of, categories.

Logical Fallacies

  • Definition: Mistakes in reasoning that weaken arguments.

  • Common Fallacies:

    • Bandwagon / Ad Populum: Concludes something must be true because it's popular.

    • Fallacies of Accuracy: Misleading information.

    • Fallacies of Insufficiency: Inadequate evidence to support claims.

    • Fallacies of Relevance: Irrelevant evidence used.

    • Straw Man: Misrepresenting arguments to make them easier to attack.

    • Either-or Fallacy: Presents limited options.

    • Circular Reasoning: Conclusion is equivalent to premise.

    • Ad Hominem: Personal attacks instead of addressing the argument.

    • Begging the Question: Premise assumes the conclusion's truth.

    • Appeal to False Authority: Claims true based on authority outside their expertise.

    • Post Hoc: Faulty cause-and-effect reasoning.

    • Hasty Generalization: Conclusions based on insufficient evidence.

    • Slippery Slope: Presents a chain of events leading to negative outcomes.