Mastering Argument Evaluation: Truth, Logic, Relevance, Non-Circularity

2. Chapter 7 Evaluate Arguments: Four Basic Tests

3. Learning Outcomes • Explain the four presumptions about argument making we make when we offer one another reasons to support our claims • Evaluate the worthiness of arguments by applying the four tests: Truthfulness of the Premises, Logical Strength, Relevance, and Non-Circularity • Recognize common reasoning mistakes known as fallacies of relevance

4. Chapter Opening Video

5. Giving Reasons and Making Arguments • Truthfulness • Logical strength • Relevance • Non-circularity

6. Truthfulness • People expect that the statements offered when making arguments are true • If a disagreement about the truth of any statement should arise, people involved can: • Make an effort to find out if that statement is true • Qualify the force with which they assert and maintain any claims in the line of reasoning that relies on the statement • Premise - Statement that is a component of a reason

7. Logical Strength • The speaker’s reason is supposed to be the logical basis for his or her claim • The assumed truth of the premises of an argument justifies or implies that the conclusion also be taken as true

8. Relevance • Conclusion can be true independent of whether the premises are true or logically support the conclusion • So What? presumption • The listener takes the speaker’s reason to be relevant in believing the speaker’s claim

9. Non-circularity • Claim must not be part of the basis for believing in the truth of the reason • Argument making is directional

10. Four Tests for Evaluating Arguments • Test #1: Truthfulness of the premises • Test #2: Logical strength • Test #3: Relevance • Test #4: Non-circularity • Argument making contexts

11. Test #1: Truthfulness of the Premises • Truth or falsity of premises is a priority in critical thinking • Person must get the information straight if he or she does not have the best information

12. Test #2: Logical Strength • An argument passes the test if there is no possible scenario in which all the premises can be true while its conclusion is false • Sound argument: Contains true premises and passes the Test of Logical Strength • Multiple independent reasons can be provided for a given claim

13. Map 1

14. Test #3: Relevance • Test requires making a reasoned judgment that the truth of the conclusion depends upon the truth of the reason • People with knowledge and experience appropriate to context and issues under discussion can easily apply the test

15. Test #4: Non-circularity • Requires that a claim is not relied upon a chain of reasoning used to support its own reason • Argument flows in one direction, from reasons and evidence toward the conclusion

16. Map 2

17. Map 3

18. Simulation

19. Argument Making Contexts • Desire for best knowledge is trumped by the competitive need to vanquish the opposition • Argument making includes the search for facts that support one’s preconceptions • Winning an argument does not guarantee that a best decision is made • Vocabulary used to evaluate arguments must be flexible

20. Evaluative Adjectives for Arguments and Their Elements

21. Common Reasoning Errors • Fallacies of relevance

22. Fallacies of Relevance • Appeals to ignorance • It is false to assume that the absence of a reason for an idea should count as a reason against the idea • Appeals to the mob • One should not assume that because a large group of people believe in something or do something, their opinion is correct

23. Fallacies of Relevance • Appeals to emotion • False to assume that one’s initial emotional response to an idea, event, story, person, image, or proposal is the best guide for forming reflective fair-minded judgments • Ad hominem attacks • Claims that a person’s ideas must be tainted because the person has some vice or flaw

24. Fallacies of Relevance • Straw man fallacy • Assuming that, by refuting a weaker argument among several independent reasons, one has successfully refuted all the reasons for a claim • Includes the practice of attributing to the opposition an argument that is not theirs, and then demolishing that argument

25. Fallacies of Relevance • Playing with words fallacy • Exploits problematic vagueness, ambiguity, donkey cart expressions, stereotyping, and slanted language in order to support a claim • Misuse of authority fallacy • False assumption that if a powerful person makes a claim, then the claim must be true

26. Discussion Question • Give an example of a recent argument that fails one or more of the four tests for evaluating arguments • State the argument and explain which test or tests it failed and why

27. Sketchnote Video