How We Know What Isn’t So

1. How We KnowWhat Isn’t So

2. We question all our beliefs, except for the ones that we really believe, and those we never think to question.Orson Scott CardAmerican Author

3. Ways of Knowing • • Personal Experience • • Reason and Intuition • • Authority • Tradition • Systematic Inquiry

4. Personal Experience

9. So what?

10. Leading Causes of Deaths (15-19) <1% each Data Source: National Center for Health Statistics National Vital Statistics Reports March 7, 2005

11. Driving and Cell Phones • • Leading cause of death among older teenagers is automobile accidents • Leading cause of automobile accidents (25-50%) is “driver distraction” • Talking on a cell phone while driving impairs performance to the same degree as being legally intoxicated (at .08 level) • – Use of “hands-free headset” makes no difference

12. Predictable Errors in Reasoning

13. Reason and Intuition

14. Linda Problem • Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations. • Which is more likely? • Linda is a bank teller • Linda is a bank teller and is active in the feminist movement

15. Linda Problem: Conjunction Fallacy Tellers Tellers who are feminists Tellers who are feminists who also play the saxophone Tversky, A., & Kahneman, D. (1983). Extension versus intuitive reasoning: The conjunction fallacy in probability judgment. Psychological Review 90, 293–315.

16. Authority

17. Expert Wine Tasters: Round One • 57 French wine experts were served two identical wines, one poured from an expensive Grand Cru bottle and the other from a cheap Vin de Table bottle. • Important: Both bottles contained the same wine – a mid-ranged Bordeaux.

18. Expert Wine Tasters: Round One • “Excellent” • “Good” • “Complex” • “Long” • “Round” “Unbalanced” “Short” “Flat” “Simple” “Faulty” Grand Cru Vin de Table

19. Expert Wine Tasters: Round Two • In another study, 54 French wine experts were served a white wine under normal conditions. The following day they were served the same white wine…but this time it was colored with a flavorless dye to look like a red wine.

20. Expert Wine Tasters: Round Two • “Fresh” • “Dry” • “Lemon” • “Apricot” • “Honey” “Deep” “Red currant” “Cherry” “Raspberry” “Spice”

21. “The Wine Trials” & F. Brochet

22. Champagne Comparison • Dom Pérignon Cuvée • France • Ranked 17 of 27 Domaine Ste. Michelle Brut United States Ranked 1 of 27 $150 $15

23. Cola Taste Test RC Cola Coca-Cola Pepsi Sam’s Choice (Walmart)

24. Controls • • Double-blind • All soda was refrigerated overnight • The order of soda presentation was systematically varied

25. Tasting

26. Question 1: Perceived Quality (Pre-Taste) • “Rate each of these colas on a scale from 0 to 10 where 0 is the lowest and 10 is the highest.”

27. Question 4: Actual Quality (Post-Taste) • “Rate each of the samples on a scale from 0 to 10 where 0 is the lowest and 10 is the highest.”

28. Tradition(Conventional Wisdom)

29. Dueling Proverbs

30. Dueling Proverbs

31. Dueling Proverbs

32. Dueling Proverbs

33. Dueling Proverbs

34. Dueling Proverbs

35. Dueling Proverbs

36. Systematic Inquiry

37. Too often we enjoy the comfort of opinion without the discomfort of thought.John F. KennedyU.S. President

38. How Not to Talk to Your Kids

39. Experiment: Round 1 • Researchers took fifth grade children out of class – one at a time – for a short nonverbal IQ test consisting of easy problems • After each child finished the test, the researchers gave the child his/her score and one line of praise…either: • – “You must be smart at this.” • – “You must have worked really hard.”

40. Experiment: Round 2 • Next, the students were given a choice of problem sets for the second round: • – One that was easy • – One that was hard • 90% of those praised for their effort chose the harder set of problems • A majority of those praised for being smart chose the easier set of problems

41. Experiment: Round 3 • In the third round, none of the fifth graders had a choice. The test was difficult – designed for kids two years ahead of their grade level. • Predictably, everyone failed. • Children praised for their effort assumed that they hadn’t focused hard enough. • Children praised for being smart assumed they weren’t really smart after all.

42. Experiment: Round 4 • In the final round, the tests were engineered to be as easy as the first round • Those praised for their effort significantly improved their score – by 30% • Those praised for their intelligence did worse than they did in the first round – by 20%

43. The Researchers’ Conclusions • Emphasizing effort gives a child a variable they can control – they respond by exerting more effort. • Emphasizing natural intelligence (being smart) takes success out of the child’s control, and it doesn’t provide a means for responding to failure – children will avoid activities they are not naturally good at.

44. It is not what the man of science believes that distinguishes him, but how and why he believes it. His beliefs are tentative, not dogmatic; they are based on evidence, not on authority or intuition.Bertrand RussellBritish Philosopher

45. In conclusion…

46. How Can We Know What Is So? • No “way of knowing” is infallible • But systematic inquiry is the most reliable way to know about the world • – It applies to every facet of life • – but it takes knowledge, skill, and effort • – The payoffs can be enormous

47. Andy Van Schaack, Ph.D.andy.vanschaack@vanderbilt.edu