How We KnowWhat Isn’t So

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

Orson Scott CardAmerican Author

Ways of Knowing

• Personal Experience• Common Sense & Logic• Tradition (Conventional Wisdom)• Authority• Systematic Inquiry

Personal Experience

So what?

Leading Causes of Deaths (15-19)

0

5

10

15

20

25

30

35

40

45

Auto Homicide Suicide Cancer Heart Congen. Other

Percentage of All Deaths

<1%each

Data Source: National Center for Health Statistics National Vital Statistics Reports March 7, 2005

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

Common Sense& Logic

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?a) Linda is a bank teller b) Linda is a bank teller and is active in the

feminist movement

Linda Problem: Conjunction Fallacy

Tversky, A., & Kahneman, D. (1983). Extension versus intuitive reasoning: The conjunction fallacy in probability judgment. Psychological Review 90, 293–315.

Authority

Expert Wine Tasters: Round One57 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.

Expert Wine Tasters: Round One

“Excellent”“Good”“Complex”“Long”“Round”

“Unbalanced”“Short”“Flat”“Simple”“Faulty”

Grand Cru Vin de Table

Expert Wine Tasters: Round TwoIn 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.

Expert Wine Tasters: Round Two

“Fresh”“Dry”“Lemon”“Apricot”“Honey”

“Deep”“Red currant”“Cherry”“Raspberry”“Spice”

“The Wine Trials” & F. Brochet

Champagne Comparison

Dom Pérignon CuvéeFranceRanked 17 of 27

Domaine Ste. Michelle Brut

United StatesRanked 1 of 27

$150 $15

Cola Taste Test

RC ColaPepsi Sam’s Choice(Walmart)

Coca-Cola

Controls

• Double-blind• All soda was refrigerated overnight• The order of soda presentation was

systematically varied

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.”

Tasting

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.”

Do Polygraphs (Lie Detector) Work?

Validity of the Polygraph

In 1993 the NSA wrote to the White House “over 95% of the information the NSA develops on individuals who do not meet federal security guidelines is derived via [voluntary admissions from] the polygraph process.”

And the Joint Security Commission noted in a 1994 report content that many polygraph proponents are “content that as long as the polygraph elicits admissions to screen out unsuitable applicants and actual security risks, the questions about the polygraph’s validity remain academic.”

Tradition(Conventional

Wisdom)

Dueling Proverbs

Good things come to those that wait

The early bird gets the worm

Many hands make light workToo many cooks spoil the

broth

Look before you leap He who hesitates is lost

A stitch in time saves nine If it ain’t broke, don’t fix it

The pen is mightier than the sword

Actions speak louder than words

Birds of a feather, flock together

Opposites attract

Systematic Inquiry

How Not to Talk to Your Kids

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.”

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

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.

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%

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.

In conclusion…

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