CLICKERS OUT !

Clicker Question Have you used clickers before? A) Yes B) No

Clicker Question What is your intended profession? A) Health related profession B) Business C) Engineering D) Science E) None of the above F) I don’t know

I have a fire breathing dragon in my basement. Do you believe me? A) Yes B) No C) I don’t know

HOW DO WE DEAL WITH THIS KIND OF STATEMENT? This is an extraordinary claim. Extraordinary claims require extraordinary proof. What kind of proof would we want? Can we deal with this claim scientifically?

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 RAZOR 3. Measurements are used 4. Science stimulates further discovery 5. 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 Method “Scientific Method” Step 1. Ask a question Step 2. Form an hypothesis Inductive Reasoning Hypothesis

Characteristics of a Good Hypothesis Characteristics of a Good Hypothesis 1. Simple 1. Simple 2. Consistent with known facts 2. Consistent with known facts 3. Probable 3. Probable 4. Uses physical explanations 4. Uses physical explanations 5. Stimulates research 5. Stimulates research 6. Makes predictions 6. Makes predictions 7. Testable 7. Testable

Step 3. Make Predictions (= Deductions) Hypothesis Hypothesis Deductive reasoning Deductions Deductions Step 4. Test the deductions using observations & experiments using observations & experiments Falsification Test is best

Step 5. On the basis of the data: make conclusions about validity of the hypothesis New Tests & New Hypotheses Science is self-correcting DATA SUPPORTED REJECTED HYPOTHESIS

When do we accept an hypothesis? 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 by the scientific community as by the scientific community as “true, beyond all reasonable doubt.” “true, beyond all reasonable doubt.”

From Hypothesis to Theory HYPOTHESIS THEORY (Guess) (Major Conceptual Framework) SpeculativeCertain SimpleElaborate Little Explanatory PowerGreat Explanatory Power

WHICH ONE OF THE FOLLOWING STATEMENTS IS A SCIENTIFIC THEORY? A) A camel is a mammal. B) People should have 2 children per family. C) If the world’s population grows beyond 10 billion, then a massive natural die-off will occur. D) The cell is the basic unit of living organisms and is generally composed of the same basic subunits wherever it occurs. All living cells are derived from previous cells. E) Ozone molecules in the earth’s atmosphere are being broken apart by CFCs (chlorofluorocarbons).

WHICH OF THE FOLLOWING STATEMENTS IS A SCIENTIFIC THEORY? 1. A camel is a mammal. (FACT) 2. People should have 2 children per family. (OPINION) 3.If the world’s population grows beyond 10 billion, then a massive natural die-off will occur. (PREDICTION) 4. The cell is the basic unit of living organisms and is generally composed of the same basic subunits wherever it occurs. All living cells are derived from previous cells. (CELL THEORY) 5. Ozone molecules in the earth’s atmosphere are being broken apart by CFCs (chlorofluorocarbons). (FACT)

Example of the Hypothetico-Deductive Method 1: Question: Why are Guaiacum sanctum plants much more likely to stay alive than most plants? 2: Hypothesis: the plant produces defensive chemicals that are toxic or make it taste bad 3: Test: feed leaves to crickets

4: Data: 92% of crickets eating Gusa leaves died, but only 14% eating regular diet died 5: Conclusion: Hypothesis is supported--

New Question: Did the crickets die because they were poisoned or because leaves tasted so bad they wouldn’t eat them? So, hypothesis is refined and tested again. Can you design an experiment to distinguish between these alternatives?

Example: Hypothetico-Deductive Method Question: Is there a fire-breathing dragon in the basement? Hypothesis: There is a fire-breathing dragon in the basement Prediction: ? 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 this Then Hypothesis is falsified! (Rejected)

THE DATA LOOK LIKE THIS

Conclusion? Conclusion? Hypothesis is Hypothesis is supported! supported!

DATA FOR 2007 BIO 200 CLASS

AND AND THE THE DATA DATA PLEASE PLEASE

Conclusion? Conclusion?

SO????