What is Science?

Science: [scientia, knowledge]

1. Knowledge gained through experience…2. Accumulated and accepted knowledge that has

been systematized and formulated with reference to the discovery of general truths or the operation of general laws

3. Branch of study that is concerned with observation and classification of facts concerned with the physical world and its phenomena

In order to do science we have to make the following assumptions:

• There is order to the universe (even if it is chaotic order)

• The human mind is capable of comprehending this order

• If conditions are the same, the results of any study will be the same

‘God does not play dice with the universe.’

Or does She?

Science can only state what is, not what should be.

Albert Einstein

Which of the following statements can be tested scientifically?

• Most of the energy coming from the sun is in the form of visible light.

• Unicorns exist.• Shelley wrote beautiful poetry.• The Earth was created over four billion years

ago.• Diamond is harder than steel.• Diamonds are more beautiful than rubies.

• The claim is sometimes made that the scientific method produces closer and closer approximations to "reality."

• Is this a scientific statement? Why or why not?

The Scientific Method

Scientists develop their knowledge by observation and experimentation

Observation is used in two ways:1. Inductive reasoning - discovering general principles

by the careful examination of specific cases. Here the scientist organizes data (facts) into categories and asks what they have in common

2. Deductive reasoning starts with general cases and proceeds to specific cases - it makes relationships clearer and allows predictions to be made

Scientific knowledge advances by a method known as "strong inference"

Strong inference works as follows:1. Make an observation or measurement2. State an hypothesis 3. Test the hypothesis 4. Publish the results5. Restate the hypothesis, test again

Observation

Semmelweis (1856), observed in hospitals inVienna, that 5X the number of women died during childbirth if they were attended by a physician as compared to being attended by a nurse(“childbed fever”).

One of his colleagues died of childbed fever aftercutting his hand with a scalpel during anautopsy.

Doctors are often doing autopsies beforeattending to childbirths.

Observation

Hypothesis(inductive reasoning)

Semmelweis hypothesized that “cadaveric matter” was transmitted from the autopsy room to the delivery room.

Observation

Hypothesis

Prediction

(DeductiveReasoning)

(inductive reasoning)

null hypothesis vs.alternative hypothesis

Washing hands would eliminate thecadaveric matter and reduce childbedfever.

Observation

Hypothesis

Prediction

Experiment

Observation

(DeductiveReasoning)

(inductive reasoning)

Experimental design•controls•dependent variable (what’s affected)•independent variable (what’s the “cause”)•predicted data (must be able to differentiate between null and alternative hypotheses)

correlation ≠ causation

correlation ≠ causation

Observation

Hypothesis

Prediction

Experiment

Observation

Analysis(Observation = Prediction?)

(DeductiveReasoning)

[Experiment]

(inductive reasoning)

Childbed fever deaths absentwhen physicians washedtheir hands

Childbed fever deaths absent when physicians washed their hands

Semmelweis

Observation

Hypothesis

Prediction

Experiment

Observation

Analysis(Observation = Prediction?)

Conclusion

(DeductiveReasoning)

[Experiment]

(inductive reasoning)

Transmission ofcadaveric matter causeschildbed fever

Observation

Hypothesis

Prediction

Experiment

Observation

Analysis(Observation = Prediction?)

Conclusion

(DeductiveReasoning)

[Experiment]

(inductive reasoning)

What other hypothesescould be made from theconclusion?

Observation

Hypothesis

Prediction

Experiment

Observation

Analysis(Observation = Prediction?)

Conclusion

(DeductiveReasoning)

[Experiment]

(inductive reasoning)

What would youpredict from yourhypothesis?

How would youtest it experimentally?

Observation

Hypothesis

Prediction

Experiment

Observation

Analysis(Observation = Prediction?)

Conclusion

(DeductiveReasoning)

TheoryLawFact

Generalization

(Deductive Reasoning)

[Experiment]

(inductive reasoning)

Initial Observation

Hypothesis

reasoning?

Experiment

Observation/Data Analysis

Interpretation

Hypothesis not Supported

NewHypothesis

NewExperiment

NewObservation

Final Hypothesis Supported

Theory

Scientific methodis a repetitiveprocess that leadsto the buildingof theories

Identifying Patterns

Hypothesis

Prediction

PreconceptionsPreconceptions ObservationsExperimentation Data

Preconceptions can influence scientific method

For childbed fever: “vapors”, spontaneous generation, women as “weak”

accumulatedscientific data

formulation of hypothesis

observation andexperimentation

new data conclusions

1 2 3 etc

theory

Theories in sciencebuild from theaccumulation of multipleinvestigative efforts

communicable disease

Summary

• The scientific method is in essence a process of observing natural phenomena which leads to the asking of questions about those phenomena which leads to the offering of explanations that can subsequently be tested

Mystery Box

• Hand out mystery boxes• Do hypothesis testing exercise