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

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 Mono Lake? • 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.

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 • 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 there 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.