What is Science? Human Biology 1/18/16. … a tool that allows us to get and organize knowledge of...

What is Science?

Human Biology1/18/16

• A process whose essential characteristics are 1) guided by natural law; 2) is explanatory by natural law; 3) is testable against the empirical world; 4) is falsifiable.– William R. Overton, U.S. District Judge in a ruling prohibiting

an AR law giving balanced time for creation-science and evolution, 1982

• The observation, identification, description, experimental investigation, and theoretical explanation of natural phenomena.– American Heritage Dictionary

• Above all it is a methodology for acquiring testable knowledge about the natural world.– Stephen Jay Gould

• A process: methodology for generating new knowledge based on cycling the following progression: observation, explanation, prediction, test, results, conclusion. A product: new knowledge with the following characteristics: it is cumulative, knowledge expanding, explanatory, predictive, systematic, testable, verifiable, tentative, self-correcting.

-OSU professor

• OR…… a way of baffling the uninitiated with incomprehensible

jargon. It is a way of obtaining fat government grants. It is a way of achieving mastery over the physical world by threatening it with chaos and destruction.

Scientific Method

• Observation

• Hypothesis

• Prediction

• Test of prediction

Scientific MethodTest of prediction–Treatment versus control group• Independent vs dependent variables• “control” confounding variables

– large sample size

–Cause and effect conclusions

Scientific Method

• Types of (dependent) variables1. Categorical (color, sex)2. Discrete (number of fingers or leaves)3. Continuous (weight, height)

• Appropriate ways to graph the above?

Scientific MethodTest of prediction

–Hypothesis vs null hypothesis

– Statistics is a tool

Scientific Method

3 Criteria of a good prediction

1.Improbability

2.Deducibility

3.Testable

Scientific Method

• Prediction is true – reject the null hypothesis– Conclude: data are consistent with the hypothesis– NOT: data prove the hypothesis

• Or prediction is false

Scientific Method

• Conclusions are published

• Conclusions are challenged by others

Scientific MethodThink about the Scientific MethodThink about bacteria: what do you know about bacteria? Where does it occur? What does it do? What does it need to grow?•In groups of 3-4, list some observations about bacteria•Generate possible explanations (hypotheses) that could explain your observations

Is Science Objective?• “The objectivity of SCIENCE, imperfect as it is, is

not a function of the objectivity of SCIENTISTS. It is a function of the “logical” rules of the game. These are embodied in the specification of a good test, and thus in Conditions 1 and 2. So there is no reason why scientists should not try to justify their hypotheses and be very disappointed if they are refuted. The rules of the game ensure that the harder one tries to get a good justification, the greater the risk of refutation – unless the hypothesis is indeed on the right track.”– R.N. Giere, 1984. Understanding Scientific Reasoning

Science and Society• What obligations does Science have towards

Society?– Tax dollars support a lot of scientific research

– Ethical questions

Deductive Arguments• Moves from the general to the specific

• If the premises are true, then it is impossible for the conclusion to be false (valid).

Examples of Deductive ArgumentsAll CU students are mammals.All mammals have lungs.Therefore, all CU students have lungs.• Valid, true premises; sound

If it is snowing, then CU cancels classes.It is snowing.Thus, CU cancels classes.• Valid, false premise; unsound

Inductive Arguments• Move from the specific to the general

• Strong: if premises are true then it’s probable that the conclusion is true.

• Cogent: an inductive argument that is strong and has all true premises

Examples of Inductive arguments

Bill is a partier.Most business majors are partiers.Thus, Bill is probably a business major.• Strong but not necessary support for conclusion

Deductive vs Inductive

Which tends to expand knowledge?

Which tends to preserve truth?

Which has valid, sound arguments?

Which has cogent, strong arguments?

Deductive vs Inductive

Which tends to expand knowledge?– inductive

Which tends to preserve truth?– deductive

Which has valid, sound arguments?– deductive

Which has cogent, strong arguments?– inductive

3 Types of Scientific Inquiry1. Discovery science – relies upon making observations and descriptions

of nature

– Gathers and catalogs facts via discovery and detection of patterns

– Asks who, what, where and when

3 Types of Scientific Inquiry2. Hypothesis-based (theoretical) Science– Explains and predicts by generating and testing

models

– Involves the proposal of hypotheses or possible explanations

– Asks why and how

3 Types of Scientific Inquiry

3. Technological Science

– New methodology or process

– Problem solving

Models

• Models are used to represent reality

• They are used to make predictions about reality

Facts, Laws and Theories• Observation– Example: it’s raining outside

• Law – Example: Dalton’s Law

• Theory – a “meta-hypothesis” that explains why an observation occurs

“A theory is a metascientific elaboration, distinct from the results of observation but consistent with them. By means of it a series of independent data and facts can be related and interpreted in a unified explanation. A theory’s validity depends on whether or not it can be tested against the facts; wherever it can no longer explain the latter, it shows its limitations and unsuitability. It must then be rethought,”– John Paul II. 1997. The Pope’s Message on

Evolution. Quarterly Review of Biology 72(4): 381-383

Deformed and declining populations of amphibians

Could a parasite be blamed?

Observational study

• Johnson et al. (1999) surveyed ponds to determine that frogs with deformities were only present if the parasite’s intermediate host snail was also present

Controlled lab experiment

Field experiment