1. Fallacies - Weak Induction

2. Homework Review: Fallacies » pp. 103-105, §4.1 “Fallacies in General” » pp. 121-131, §4.3 “Fallacies of Weak Induction” Inductive Argumentation » Analogical Reasoning, e.g., ex. 8.4 » Causal Argumentation, e.g., 8.3b » Inductive Generalization, e.g., 8.2b Read for Next Class – pp. 106-116, §4.2 “Fallacies of Relevance”

3. ANALOGICAL REASONING Induction – Final Unit

4. Analysis – Identify Subject and Analogue Criticism 1.Are common features relevantly similar to inferred feature? 2.Is there a disanalogy? Arguments from Analogy? Both my dog and my neighbor's dog are well- loved members of the family. Each one is well fed, house broken, walked on a regular basis. My dog has a very calm temperament. So I infer that my neighbor's dog also has a calm temperament.

5. WEAK INDUCTION Fallacies Transition

6. Kinds of Fallacies a defect or error traceable to the very structure (or form) of the argument a defect which can be detected only by reference to the content of an argument vsFormContent Formal FallaciesInformal Fallacies

7. Kinds of Informal Fallacies Fallacies of: 1.Relevance 2.Weak Induction 3.Presumption 4.Ambiguity a.Amphiboly/Equivocation b.Whole/Part See pages 153f for a complete list Only required to classify each fallacy according to these four types

8. Your Task on the Exam Explain how the argument is fallacious. Fallacies on Exam fallacy of relevance fallacy of weak induction fallacy of presumption fallacy of ambiguity none of the above

9. WEAK INDUCTION Fallacies

10. Weak Induction Inferential connection – evidence not strong enough to support conclusion Premises are relevant to conclusion Premises do not warrant conclusion

11. The Five Fallacies of Weak Induction 1.Appeal to Ignorance 2.Appeal to Unqualified Authority 3.Hasty Generalization 4.False Cause 5.Weak Analogy In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion

12. The Five Fallacies of Weak Induction 1.Appeal to Ignorance 2.Appeal to Unqualified Authority 3.Hasty Generalization 4.False Cause 5.Weak Analogy In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion See earlier presentations for assessment criteria

13. The Five Fallacies of Weak Induction 1.Appeal to Ignorance – Smoking has not been proven to cause cancer, therefore tobacco products are not carcinogenic Premises offer only a lack of evidence A definite assertion is made on this basis In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion Exceptions 1.If search for evidence has been (seemingly) exhaustive by qualified personnel 2.American Legal Standard: “reasonable doubt” Exceptions 1.If search for evidence has been (seemingly) exhaustive by qualified personnel 2.American Legal Standard: “reasonable doubt” See in-class example: Mill’s Method of Residue

14. The Five Fallacies of Weak Induction 2.Appeal to Unqualified Authority – I was speaking to my brother at his auto shop, and he believes the Democrats will lose Maryland in the next election. So I think it’s likely. Premises offer testimony/opinion from an authority Conclusion about subject matter is made on this basis In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion Question rests on the relevant expertise of the authority consulted

15. The Five Fallacies of Weak Induction 3.Hasty Generalization See Presentation “Induction: Generalizations”Induction: Generalizations In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion Two Issues Affecting Strength Representativeness of Sample Interviewer Bias Two Issues Affecting Strength Representativeness of Sample Interviewer Bias

16. The Five Fallacies of Weak Induction 4.False Cause – Four variants (complex fallacy) a.Post hoc ergo propter hoc (“after this, there because of this”) b.Non causa pro causa (“non-cause for the cause”) c.Oversimplified cause d.Slippery Slope

17. The Five Fallacies of Weak Induction 4.False Cause: – After we arrived, the baby got sick. So I think we were the cause of the baby’s illness. No causal relation apparent or explained Causal conclusion based on mere temporal succession “after this” In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion

18. The Five Fallacies of Weak Induction 4.False Cause: – Computer scientists do better at logic. So to do better in this course, you should study computer science Typically, no assertion of temporal succession Mistaken assertion of causal agency “non-cause” In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion

19. The Five Fallacies of Weak Induction 4.False Cause: – Your car is causing global warming. Phenomenon in question caused by complex number of factors A single one of these factors is asserted as sole cause oversimplification In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion

20. The Five Fallacies of Weak Induction 4.False Cause: If you fail this class, then your GPA will go down. If you GPA falls, you’ll lose your scholarship. If you lose your scholarship, you’ll spend all your money on school. If you do this, you’ll have no money for food and shelter. So if you fail this class, you will become a starving, homeless beggar. – A chain of causal events is asserted – The causal connection between some or all events is highly unlikely » At least the ultimate conclusion is highly unlikely slippery slope In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion

21. The Five Fallacies of Weak Induction 5.Weak Analogy In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion In each case, 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion See earlier slides of this presentation! Two Issues Affecting Strength Common features relevantly similar to inferred feature No relevant dissimilarities (no disanalogy) Two Issues Affecting Strength Common features relevantly similar to inferred feature No relevant dissimilarities (no disanalogy)

22. Both my dog and my neighbor's dog are well- loved members of the family. Each one is well fed, house broken, walked on a regular basis. My dog has a very calm temperament. So I infer that my neighbor's dog also has a calm temperament. Arguments from Analogy?

23. Fallacies of weak induction – Five identifiable kinds – Not expected to provide the names of these on exam Fallacies on Exam In each case: 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion In each case: 1.The premises are relevant to conclusion 2.Premises provide insufficient evidence to warrant conclusion

24. Homework Review: Fallacies » pp. 103-105, §4.1 “Fallacies in General” » pp. 121-131, §4.3 “Fallacies of Weak Induction” Inductive Argumentation » Analogical Reasoning, e.g., ex. 8.4 » Causal Argumentation, e.g., 8.3b » Inductive Generalization, e.g., 8.2b Read for Next Class – pp. 106-116, §4.2 “Fallacies of Relevance”