What is Science?

Plan for Today

1) Recap Weber’s insights

2) Attributes of scientific evidence

3) Example

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Scientific Evidence

Two Key definitions


(For our purposes) a statement about what is true or valid. *If you can add “is true” to the end or “it is true that” to the beginning of the statement without changing the meaning, it is a claim.

Don’t overthink this definition. It is as simple as it seems.

Two Key definitions


(For our purposes) the basis for a claim is the reason we should accept the truth or validity of that claim. It is the evidence that is used to “prove” the claim is true and the assumptions required for the evidence to be valid “proof” (sometimes called the “warrant”)

An example:

claim: “It rained last night”

basis: “The street is wet”

What is the evidence? What are the assumptions behind that evidence?

Using Science to Evaluate Claims

Science is distinct in

(1) Only certain claims can be investigated

(2) Having special rules for using evidence and making assumptions to accept claims

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Scientific Evidence:

Scientific Evidence:

Systematic use of evidence

Transparent procedures

Acknowledge uncertainty

Test claim against alternatives

Transparent procedures

How did you arrive at your conclusion?

  • What data / observations did you use?
  • What comparisons did you make?
  • What choices as a researcher did you make, and why


  • Others can know the assumptions required to find result
  • Others can question your choices
  • Others can replicate your work (objectivity)

Consider alternatives

Test your claim against other competing claims

  • Whichever claim “survives” many different tests is best


  • Openness to being wrong (no assumption above challenge)
  • One piece of evidence can be consistent with many claims
  • Best claim generates most useful predictions

Systematic Use of Evidence

Observations we make:

  • Clear rules for what we observe
  • Clear rules for how we observe
  • Clear rules for comparison
  • Avoids “cherry-picking”


  • Cherry picking assumes a truth, picks data
  • Cherry picking doesn’t consider alternatives
  • Need to be able to consider challenge to our evidence

Acknowledge uncertainty

Limitations of finding:

  • What questions remain unanswered after your study (what didn’t it tell us)
  • What assumptions did we make that might not be true?

How certain or precise are our answers?

  • Acknowledge possibility of chance relationships
  • How confident can we be about our results being real?

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Consider a claim:

A person’s prejudice against a group of people can be reduced through meaningful, interpersonal contact with a member of that group.

An investigation

2014 paper in Science: researchers conduct an experiment


Are efforts to change the minds of opponents same-sex marriage through conversation more successful when they are done by homosexuals (compared to heterosexuals)?

One hand = NO; Two hands = YES

Should we believe the results?

To believe the results

What do you need to know…

about Transparent Procedures?


Who was treated?

How did they get treated?

What were the survey questions?