1. 1 Reasoning Chapter 8

2. 2 Forms of Proof Logos = Logical evidence Logos = Logical evidence Ethos = Ethics/Credibility Ethos = Ethics/Credibility Pathos = Emotional appeals Pathos = Emotional appeals

3. 3 Inferences Mental leaps made when listener agrees that evidence supports claims Mental leaps made when listener agrees that evidence supports claims

4. 4 Argument Set of statements that develops evidence to establish validity of claims Set of statements that develops evidence to establish validity of claims Patterns of reasoning help organize argument Patterns of reasoning help organize argument Not a fight or angry dispute Not a fight or angry dispute

5. 5 Patterns of Reasoning Induction: Induction: reasoning from specific instances Deduction: Deduction: reasoning from a general principle

6. 6 Guidelines for Inductive Reasoning Enough examples for claim Enough examples for claim Accurate generalizations Accurate generalizations Support arguments Support arguments

7. 7 Reasoning inductively Inductive thinking; specific to general Inductive thinking; specific to general –Fermi II has operated since 1985 w/o incident –Davis Besse has been in operation since 1977 w/o a serious problem –Perry plant in Cleveland, OH has been in operation since 1986 w/o a problem –Nuclear power can be managed safely

8. 8 Hasty Generalizations Reaching a conclusion without enough evidence to support it Reaching a conclusion without enough evidence to support it

9. 9 Deductive Reasoning Major premise Major premise Minor premise Minor premise Conclusion Conclusion

10. 10 Major Premise The general principle, states a familiar, commonly accepted belief The general principle, states a familiar, commonly accepted belief

11. 11 Minor Premise The specific instance, establishes the truth of the conclusion The specific instance, establishes the truth of the conclusion

12. 12 Deductive Example Major premise: The goal of social welfare programs is to move users to self-sufficiency Major premise: The goal of social welfare programs is to move users to self-sufficiency Minor premise: Some programs create dependency Minor premise: Some programs create dependency Claim: Therefore, some social welfare programs should be changed Claim: Therefore, some social welfare programs should be changed

13. 13 Guidelines for Deductive Reasoning Establish the validity of the major premise Establish the validity of the major premise Strengthen it with additional evidence or reasoning Strengthen it with additional evidence or reasoning

14. 14 Causal Reasoning Process of reasoning that supports a claim by establishing a cause-and-effect relationship Process of reasoning that supports a claim by establishing a cause-and-effect relationship

15. 15 Guidelines for Causal Reasoning Avoid false causes Avoid false causes Avoid assuming an event has only one cause Avoid assuming an event has only one cause Cite supporting evidence to strengthen cause-and- effect relationships Cite supporting evidence to strengthen cause-and- effect relationships

16. 16 Analogical Reasoning Suggesting because two conditions or events resemble each other in certain ways, they will resemble each other in other ways Suggesting because two conditions or events resemble each other in certain ways, they will resemble each other in other ways

17. 17 Analogical Example Handguns are banned in Canada and they have low crime rates Handguns are banned in Canada and they have low crime rates If the U.S. banned handguns there would be a drop in violent crimes If the U.S. banned handguns there would be a drop in violent crimes

18. 18 Reasoning by Sign Something exists or will happen based on something else that exists or has happened Something exists or will happen based on something else that exists or has happened

19. 19 Reasoning by Sign Example A doctor reasons that a high temperature signals infection in the body A doctor reasons that a high temperature signals infection in the body

20. 20 Guidelines for Reasoning by Sign Is alternative explanation more credible? Is alternative explanation more credible? Assure sign is not an isolated instance Assure sign is not an isolated instance If instance in which a sign does not indicate a particular event, argument not solid If instance in which a sign does not indicate a particular event, argument not solid

21. 21 A Map of Reasoning

22. 22 Grounds Why do you think this or want to propose it? Why do you think this or want to propose it? Check out Web Link 8.2: Toulmin Model at the Invitation to Public Speaking website.

23. 23 Warrant How do you know your grounds support your claim? How do you know your grounds support your claim?

24. 24 Backing How do you know the warrant supports the grounds? How do you know the warrant supports the grounds?

25. 25 Claim What do you think or want to propose? What do you think or want to propose?

26. 26 Reasoning Ethically Build credibility Build credibility Use accurate evidence Use accurate evidence Verify the structure of reasoning Verify the structure of reasoning