CLICKERS OUT !CLICKERS OUT !

Clicker QuestionClicker Question

Have you used clickers before?Have you used clickers before?

A) YesA) Yes

B) NoB) No

Clicker QuestionClicker QuestionWhat is your intended profession?What is your intended profession?

A) Health related professionA) Health related profession

B) BusinessB) Business

C) EngineeringC) Engineering

D) ScienceD) Science

E) None of the aboveE) None of the above

F) I don’t knowF) I don’t know

I have a fire breathing dragon in my I have a fire breathing dragon in my basement.basement.

Do you believe me?Do you believe me?

A) YesA) Yes

B) NoB) No

C) I don’t knowC) I don’t know

HOW DO WE DEAL WITH THIS HOW DO WE DEAL WITH THIS KIND OF STATEMENT?KIND OF STATEMENT?

This is an extraordinary claim.This is an extraordinary claim.

Extraordinary claims require extraordinary Extraordinary claims require extraordinary proof.proof.

What kind of proof would we want?What kind of proof would we want?

Can we deal with this claim scientifically?Can we deal with this claim scientifically?

WHAT IS SCIENCE?WHAT IS SCIENCE?

What is

Science?

Hmmm?

Science is an attempt to

explain the natural world in terms of

natural processes, not supernatural

ones!

SCIENCE AS A WAY OF KNOWING

“Science .... Is the organized, systematic enterprise that gathers knowledge about the world and condenses the knowledge into testable laws and principles.” E.O. Wilson

Science is....

• a body of facts and principles about the physical world

• a method of discovery

Characteristics of Science

1. Testable: repeatable observations and experiments

2. Law of parsimony — “OCCAM’ S RAZOR3. Measurements are used4. Science stimulates further discovery5. Consilience Principles of many fields are consistent with the

discovery

• Astronomy, chemistry and evolution are science.Astrology, pyramid power and “creationism” are not science.

Types of Reasoning

Deductive Reasoning

General------- Specific

Applying a set of general logic rules

to a particular problem

******

Inductive Reasoning

Specific----- General

Generalizing on the basis of some observations

Hypothetico-Deductive MethodHypothetico-Deductive Method“Scientific Method”“Scientific Method”

Step 1. Step 1. Ask a questionAsk a question

Step 2. Step 2. Form an hypothesisForm an hypothesis

Inductive ReasoningInductive Reasoning

Hypothesis

Characteristics of a Good HypothesisCharacteristics of a Good Hypothesis

1. Simple1. Simple

2. Consistent with known facts2. Consistent with known facts

3. Probable3. Probable

4. Uses physical explanations4. Uses physical explanations

5. Stimulates research5. Stimulates research

6. Makes predictions6. Makes predictions

7. Testable7. Testable

Step 3. Make PredictionsStep 3. Make Predictions

(= Deductions)(= Deductions)

HypothesisHypothesisDeductive reasoningDeductive reasoning

DeductionsDeductions

Step 4. Test the deductionsStep 4. Test the deductions

using observations & experiments using observations & experiments

Falsification Test is bestFalsification Test is best

Step 5. On the basis of the data:Step 5. On the basis of the data:

make conclusions about validity of the hypothesismake conclusions about validity of the hypothesis

New Tests & New Hypotheses

Science is self-correcting

DATA

SUPPORTED REJECTEDHYPOTHESIS HYPOTHESIS

When do we accept an hypothesis?When do we accept an hypothesis?

1. When all attempts to falsify it 1. When all attempts to falsify it

(i.e. show it false) have failed.(i.e. show it false) have failed.

2. When it is accepted 2. When it is accepted

by the scientific community asby the scientific community as

““true, beyond all reasonable doubt.”true, beyond all reasonable doubt.”

From Hypothesis to TheoryFrom Hypothesis to Theory

HYPOTHESIS HYPOTHESIS THEORY THEORY (Guess) (Guess) (Major Conceptual(Major Conceptual Framework)Framework)

SpeculativeSpeculative CertainCertain

SimpleSimple ElaborateElaborate

Little Explanatory PowerLittle Explanatory Power Great Explanatory PowerGreat Explanatory Power

WHICH ONE OF THE FOLLOWING STATEMENTS WHICH ONE OF THE FOLLOWING STATEMENTS IS A SCIENTIFIC THEORY? IS A SCIENTIFIC THEORY?

A) A camel is a mammal.A) A camel is a mammal.

B) People should have 2 children per family.B) People should have 2 children per family.

C) If the world’s population grows beyond 10 billion, then C) If the world’s population grows beyond 10 billion, then a massive natural die-off will occur.a massive natural die-off will occur.

D) The cell is the basic unit of living organisms and is D) The cell is the basic unit of living organisms and is generally composed of the same basic subunits generally composed of the same basic subunits wherever it occurs. All living cells are derived from wherever it occurs. All living cells are derived from previous cells.previous cells.

E) Ozone molecules in the earth’s atmosphere are being E) Ozone molecules in the earth’s atmosphere are being broken apart by CFCs (chlorofluorocarbons).broken apart by CFCs (chlorofluorocarbons).

WHICH OF THE FOLLOWING STATEMENTS IS A WHICH OF THE FOLLOWING STATEMENTS IS A SCIENTIFIC THEORY? SCIENTIFIC THEORY?

1. A camel is a mammal. 1. A camel is a mammal. (FACT)(FACT)

2. People should have 2 children per family. 2. People should have 2 children per family. (OPINION)(OPINION)

3.3.IfIf the world’s population grows beyond 10 billion, the world’s population grows beyond 10 billion, then then a massive natural die-off will occur. a massive natural die-off will occur. (PREDICTION)(PREDICTION)

4. The cell is the basic unit of living organisms and is 4. The cell is the basic unit of living organisms and is generally composed of the same basic subunits generally composed of the same basic subunits wherever it occurs. All living cells are derived from wherever it occurs. All living cells are derived from previous cells. previous cells. (CELL THEORY)(CELL THEORY)

5. Ozone molecules in the earth’s atmosphere are being 5. Ozone molecules in the earth’s atmosphere are being broken apart by CFCs (chlorofluorocarbons). broken apart by CFCs (chlorofluorocarbons). (FACT)(FACT)

Example of the Hypothetico-Deductive MethodExample of the Hypothetico-Deductive Method

1: Question: Why are 1: Question: Why are Guaiacum sanctumGuaiacum sanctum plants plants much more likely to stay alive than most plants?much more likely to stay alive than most plants?

2: Hypothesis: the plant produces defensive 2: Hypothesis: the plant produces defensive chemicals that are toxic or make it taste badchemicals that are toxic or make it taste bad

3: Test: feed leaves to crickets3: Test: feed leaves to crickets

4: Data: 92% of crickets eating 4: Data: 92% of crickets eating GusaGusa leaves leaves died, but only 14% eating regular diet dieddied, but only 14% eating regular diet died

5: Conclusion: Hypothesis is supported--5: Conclusion: Hypothesis is supported--

New Question: New Question: Did the crickets die because they were Did the crickets die because they were poisoned or because leaves tasted so bad they wouldn’t poisoned or because leaves tasted so bad they wouldn’t

eat them?eat them?

So, hypothesis is refined and tested again.So, hypothesis is refined and tested again.

Can you design an experiment to distinguish Can you design an experiment to distinguish between these alternatives?between these alternatives?

Example: Hypothetico-Deductive Example: Hypothetico-Deductive MethodMethod

Question: Is there a fire-breathing dragon in Question: Is there a fire-breathing dragon in the basement?the basement?

Hypothesis: There is a fire-breathing dragon Hypothesis: There is a fire-breathing dragon in the basementin the basement

Prediction: ?Prediction: ?

Test: ?Test: ?

Suppose I counter every physical test you propose with a special explanation of why it won't work.

Then what?

What's the difference between an invisible, incorporeal, floating dragon

who spits heatless fire and no dragon at all?

What should we conclude?***

In contrast, consider the following question:

If this

Then hypothesis is supported!

Example of the Hypothetico-Deductive Method

If thisIf this

Then Hypothesis is falsified! (Rejected)

THE DATA LOOK LIKE THISTHE DATA LOOK LIKE THIS

Conclusion?Conclusion?

Hypothesis isHypothesis is

supported!supported!

DATA FOR 2007 BIO 200 CLASS

ANDAND

THETHE

DATADATA

PLEASEPLEASE

Conclusion?Conclusion?

Conclusion?Conclusion?

SO????SO????