1. Chapter 2: Science as a Way of Knowing: Critical Thinking about the Environment

2. Understanding What Science Is
Scientific understanding of life and its environment is based on scientific method.
Science is a process
A way of knowing
Results in conclusions, generalizations and sometimes laws
Allows us to explain a phenomenon and make predictions (based on knowledge at the present time)

3. Science as a way of knowing
Continuous process
Sometimes a science undergoes a fundamental revolution in ideas
Science begins with observations
E.g. How many birds nest at Lake Orion?
What food do they eat?
Deals only with statements that can be disproved.

5. Disprovability
A statement can be said to be scientific if someone can state a method by which it could be disproved.
Many ways of looking at the world
Distinction between scientific statement and nonscientific is not a value judgment
Simply a philosophical one

7. Assumptions of Science
Events in the natural world follow patterns.
Basic patterns and rules are the same throughout the universe.
Based on a type of reasoning known as induction.
Generalizations can be tested and disproved.
New evidence can disprove existing scientific theories, but can never provide absolute proof.

8. Deductive reasoning Example 1
Premise: a straight line is the shortest distance between two points.
Premise: The line from A to B is the shortest distance between points A and B.
Conclusion: Therefore, the line from A to B is a straight line.
Proof does not require that the premises be true, only that the reasoning foolproof.

9. Deductive reasoning Example 2
Premise: Humans are the only toolmaking organisms.
Premise: the woodpecker finch uses tools.
Conclusion: Therefore, the woodpecker finch is a human being.

10. Inductive reasoning
Science requires not only logical reasoning but also correct premises.
Generalizations based on a number of observations = inductive reasoning.

11. All male eared grebes have golden feathers during the breeding season.

12. Probability A way of expressing our certainty
Our estimation of how good our observations are
How confident we are of our predictions
Scientific reasoning combines induction and deduction

13. Measurements and Uncertainty
When we add numbers to our analysis
Obtain another dimension of understanding
Visualize relationships
Make predictions
Analyze strength of relationships

14. Measurements and Uncertainty
Measurements are limited
Meaningless unless it is accompanied by an estimate of its uncertainty.
Two sources of uncertainty
Real variability in nature
Every measurement has some error
Called experimental error

15. Accuracy and Precision
Accuracy refers to what we know.
Precision refers to how well we measure.

16. Accuracy versus Precision
Accuracy refers to the proximity of a measurement to the true value of a quantity.
Precision refers to the proximity of several measurements to each other.

17. Observations, Facts, Inferences, and Hypotheses
Obs. - may be made by any of the five senses or instruments that measure beyond what we sense.
Inference - a generalization that arises from a set of obs.
Fact – obs about a particular thing agreed by all

18. Hypothesis Type of statement used
When scientists wish to test an inference
Can be disproved
If a hypothesis has not been disproved
Is still not proven true
Only found to be probably true

19. Variables Dependent variable – rate of photosynthesis
Independent variable – amount of light
Manipulated variable – ind var because can be changed
Responding variable – dep var because it response to change

20. Controlled Experiment
Experiment compared to a standard, or control.
An exact duplicate of the experiment except the condition of one variable being tested.
Any difference in outcome attributed to the independent variable.

21. Repeatability
Operational definitions – variables described in terms of what one would have to do to duplicate the variable’s measurements.
Oper. def. allows other scientist to repeat experiments exactly and check results.

22. Data Quantitative- numerical Qualitative- nonnumerical
E.g. diameter of a tree trunk
Qualitative- nonnumerical
E.g. species of tree

23. Models and Theories
Scientists use accumulated knowledge to develop explanations.
A Model is a “deliberately simplified construct of nature”.
Models that offer broad, fundamental explanations of observation are called theories.

24. Scientific Method
1. Make observation and develop a question about the obs.
2. Develop a tentative answer- a hypothesis.
3. Design a controlled experiment to test the hypothesis.
4. Collect data.
5. Interpret data.

25. Scientific Method 6. Draw a conclusion from the data.
7. Compare the conclusion to the hypothesis and determine whether the results support or reject the hypothesis.
8. If the hypothesis is supported, conduct additional experiments to test it further. If the hypothesis is rejected, construct a new hypothesis.

26. Scientific Method

27. Misunderstandings about Science
Scientific theory- grand scheme that relates and explains many observations and is supported by a great deal of evidence.
In everyday usage theory may mean a guess, a hypothesis, a prediction, a notion, a belief.

28. Science and Technology
Science is a search for understanding
Technology is the application of scientific knowledge that benefits humans.
The two are intertwined.
In our daily lives most of us do not encounter science but the products of science.

29. Misunderstandings about Science
Myth of objectivity or value free science.
Pseudoscientific
Untestable, lack empirical evidence or based on faulty reasoning.
Frontier science
Ideas that may move into realm or science or pseudoscience.

31. Environmental Questions and the Scientific Method
Enviro sciences deal w/ especially complex systems.
Not as neat as the scientific method.
Different approach has been used in environmental sciences.
E.g. California Condor

32. California Condor Numbers declined to 22 in the 1970’s
Suggestions to help populations
Remove all from the wild and breed in zoos
Improve habitat; returning it to grassland
Population to small to divide into two diff. study groups.
Captive breeding begun

34. California Condor
By 1990’s numbers large enough to start reintroductions.
Today there are 300 condors, 158 in the wild.
In 2003 first wild chicks fledged.
Beginning to find their own food.
Effort appears to be a success.

36. Historical Evidence Frequency of fires in the BWCA of MN.
Three kinds of data used
Written records
Tree-ring records
Buried records (fossil and pre-fossil org deposits)
Fire scars could be seen in record.

38. Historical Evidence By examining cross sections
Possible to determine the date of each fire
Number of years between fires
Heinselman determined it burned once per century.
Forests shown to be integral part of forests.

39. Historical Evidence
Historical info meets the primary requirement of scientific method
Ability to disprove a statement
Major source of data that can be used to test hypotheses in ecology.

40. Modern Catastrophes and Disturbances as Experiments
Eruption of Mount St Helens in 1980
Allowed for study of dynamics of ecological systems
1988 Wildfire in Yellowstone NP
Carefully monitored before and after.

42. Learning about Science
Open-ended process
Students often perceive science as a body of facts to be memorized.
Really a set of currently accepted truths, always subject to change.