January 14, 2019

## Example:

### LaCour and Green (2014)

Experiment on contact with gay canvasser and prejudice toward gay people.

• Hit all the key criteria

## Isn't this a problem for science?

### BUT

• Researchers saw important question
• Uncertainty $$\rightarrow$$ more work needed
• Attempt to reproduce the study
• Could not come up with same result
• Discovered Fraud

## Credibility

### A community of researchers can:

• Evaluate work of others (transparency)
• Replicate prior work (transparency)
• Identify/eliminate errors (systematic evidence, acknowledge statistical uncertainty)
• Test claims against additional counter arguments (consider alternatives)

## Unscientific bases for claims

• Many fallacies in giving evidence
• We will consider a few
• Aim to see where they fail to meet scientific criteria

## A claim

Foreign aid is beneficial

Basis for the claim:

"The war against terror is bound up in the war against poverty." Who said that? Not me. Not some beatnik peace group. Secretary of State [and retired General] Colin Powell. And when a military man starts talking like that perhaps we should listen.

• Bono

## What kind of claim is that?

### Appeal to authority (argumentum ad verecundiam)

Arguing that claim is true because a person with authority says it is true.

## Several problems

1. Experts may be wrong/expertise irrelevant
2. Experts may have an agenda
3. We can "cherry pick" supportive experts
4. Experts can disagree

## Expertise wrong/irrelevant

### Claim:

As far as the cyber, I agree to parts of what Secretary Clinton said. We should be better than anybody else, and perhaps we're not. I don't think anybody knows it was Russia that broke into the DNC. I mean, it could be Russia, but it could also be China. It could also be lots of other people. … So we have to get very, very tough on cyber and cyber warfare. It is — it is a huge problem. … The security aspect of cyber is very, very tough. And maybe it's hardly doable.

• Donald Trump

### Basis for the claim:

I have a son. He's 10 years old. He has computers. He is so good with these computers, it's unbelievable.

## Expertise wrong/irrelevant

### What's wrong with this?

lack of transparency, unacknowledged uncertainty

## Experts have motive other than the truth

### Claim:

"Climate change is not caused by human activity"

### Basis for the claim:

"These scientists say the evidence does not support the claim."

• These scientists also have had work paid for by Exxon Mobil

## Experts have motive other than the truth

### Claim:

"Given your condition, you should take this new drug, X."

### Basis for the claim:

"I am a doctor."

• This doctor receives gifts, meals, money from manufacturer of drug X.

## Experts have motive other than the truth

### What's wrong with this?

Best case to worst-case:

• unacknowledged uncertainty; lack of transparency; may not consider alternatives; unsystematic use of evidence

## Cherry picking experts

### Claim:

Millions of immigrants vote illegally in the United States

### Basis for the claim:

Two political scientists wrote an article finding more than 10% of non-citizens vote

• This ignores the hundreds of political scientists who suggest the study has major flaws

## Cherry picking experts

### What's wrong with this?

• no systematic use of evidence, lack of transparency, unacknowledged uncertainty

## Proliferating authorities

### Claim:

Millions of immigrants vote illegally in the United States

What do we do when some experts say one thing, and others say another?

## Proliferating authorities

### What's wrong with this?

• no transparency, no systematic use of evidence

## Basis for Claim: Authority

### Beware:

• The basis of authority is often "science."

• Turns science into something magic and should not make it persuasive

## A claim

Foreign aid is beneficial

Basis for the claim:

If developing countries are poor, then obviously the problem is a lack of money. So giving them more money has to help.

## Bases for claims: Common Sense

Claims from common sense:

• arguing that a claim is true because it is something "everyone knows" or "just makes sense"

## Bases for claims: Common Sense

### Problems with common sense

• Often based on superficial similarities

• Often based on analogy between very different situations

• Often good reasons what the opposite claim also makes sense

## Superficial similarities

### Claim:

"Running a large deficit will lead a country to bankruptcy and instability through large interest rates"

### Basis for the claim:

"When people or families spend more than they make, they receive higher interest rates and risk bankruptcy"

• Individuals/families have budgets, so do governments. But they are otherwise very dissimilar.

## Superficial similarities

### What's the problem here?

• unsystematic use of evidence
• failure to consider alternatives

## False analogies

### Claim:

In 2003:

"US military invasion in Iraq will bring peace, democracy, and economic growth to the country."

### Basis for the claim:

"The occupation of Germany promoted demilitarization, denazification, democratization and capitalist development while garnering widespread support within Germany and outside"

• But the places, context of invasion, and the ways they were undertaken were totally different.

## False analogies

### What's the problem here?

• unsystematic use of evidence
• failure to consider alternatives

## Opposite claims possible

### Claim and basis:

"Guns kill people, so of course gun control will reduce murders."

### Counterclaim and basis:

"People kill people, so gun control will not stop murderers, because other weapons are available."

## Opposite claims possible

• unacknowledged uncertainty
• failure to consider alternatives

## Bases for Claims: Personal experience

A claim from personal experience:

A claim based on one's own personal (nonsystematic) observation or one's own reaction to an observation

### Examples

"No one I know is voting for ____, so they won't win."

"I've had two identical watches from Timex that broke; they make poor quality products."

## Bases for Claims: Personal experience

### Personal experience can be misleading:

• We generalize too quickly from a small number of cases and our experience

• Our exposure to the world may be skewed

• We observe the world selectively

## Generalize too quickly:

### Claim

"I have a gluten intolerance".

### Basis

"I had [some product] a few times and each time I felt sick to my stomach afterwards."

## Generalize too quickly:

### What's wrong with this?

• failure to consider alternatives
• unsystematic use of evidence
• unacknowledged uncertainty

## Skewed Exposure

### Claim

"X won't win the election" "X couldn't have legally won the election"

### Basis

"No one I know is voting/voted for her."

## Skewed Exposure

### What's wrong with this?

• unsystematic use of evidence
• unacknowledged uncertainty

## Selective Perception

### Claim

"Large, public places like mass transit are more dangerous than driving."

### Basis

"Remember all those terrorist attacks or mass shootings in public places and public transit?"

## Selective Perception

### What's wrong with this?

• unsystematic use of evidence
• lack of transparency
• failure to consider alternatives

## Summary

### Many kinds of errors

• You need to recognize where they deviate from scientific bases for evidence.