chapter 2: science as a way of knowing: critical thinking about the environment
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Chapter 2: Science as a Way of Knowing: Critical Thinking about the Environment. 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 - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 2: Science as a Way of Knowing: Critical Thinking about
the Environment
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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)
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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.
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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
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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.
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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.
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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.
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Inductive reasoning
• Science requires not only logical reasoning but also correct premises.
• Generalizations based on a number of observations = inductive reasoning.
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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
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Measurements and Uncertainty
• When we add numbers to our analysis– Obtain another dimension of understanding– Visualize relationships– Make predictions– Analyze strength of relationships
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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
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Accuracy and Precision
• Accuracy refers to what we know.
• Precision refers to how well we measure.
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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.
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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
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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
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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
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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.
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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.
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Data
• Quantitative- numerical– E.g. diameter of a tree trunk
• Qualitative- nonnumerical– E.g. species of tree
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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.
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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.
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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.
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Scientific Method
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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.
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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.
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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.
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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
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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
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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.
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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.
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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.
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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.
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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.
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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.