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Chapter 2: Science as a Way of Knowing: Critical Thinking About the Environment Overview Understanding What Science is, and What it isn’t Observations, Facts, Inferences, and Hypotheses Measurements and Uncertainty Misunderstandings about Science and Society Environmental Questions and the Scientific Method 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) Science as a way of knowing Continuous process Sometimes a science undergoes a fundamental revolution in ideas Science begins with observations Example: How many birds nest at Mono Lake? What food do they eat? Deals only with statements that can be disproved 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 Observations, Facts, Inferences, and Hypotheses Observations Inference Made by any of the five senses or instruments that measure beyond what we sense Generalization that arises from a set of observations Fact observation about a particular thing agreed by all 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 Controlling Variables A valid scientific experiment keeps all variables constant, except the independent and dependent variables Controlled experiment An exact duplicate of an experiment is compared back to a standard or control One variable is altered (independent variable) This may cause a change in another variable in the experiment (dependent variable) Variables Dependent variable Independent variable amount of light Manipulated variable rate of photosynthesis Ind. variable because can be changed Responding variable Dependent variable because it responds to change Data Quantitative - numerical Ex: diameter of a tree trunk Qualitative - non-numerical Ex: species of tree Inductive v. Deductive Reasoning Scientific Reasoning combines both deductive and inductive reasoning Deductive reasoning Involves reasoning from initial definitions and assumptions Keep in mind, science requires not only logical reasoning, but correct premises Deductive reasoning 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 using deductive reasoning does not require that the premises be true, only that the reasoning foolproof Deductive reasoning Premise: Humans are the only tool making organisms Premise: the woodpecker finch uses tools Conclusion: Therefore, the woodpecker finch is a human being! Inductive v. Deductive reasoning Inductive Reasoning Example Generalizations based on a number of observations Breeding male grebes have golden feathers This is only true until we observe a breeding male grebe that does not have golden feathers Proof of inductive reasoning is stated in terms of probability of occurance Measurements and Uncertainty When we add numbers to our analysis Obtain another dimension of understanding Visualize relationships Make predictions Analyze strength of relationships Models and Theory Model A deliberately simplified construct of nature Many types of models Physical working model Pictorial model Set of mathematical equations Computer model Measurements and Uncertainty People generally put more faith into the accuracy of measurements than do scientists Measurements are useless unless accompanied by an estimate of their uncertainty Experimental error Historical Evidence- Alternative to Direct Experimentation 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 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 Fires shown to be integral part of forest ecology 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 Accuracy and Precision Accuracy What we know Extent to which a measurement agrees with the accepted value Precision How well we measure The degree of exactness with which the quantity was measured Process of Making Decisions Similar to Scientific Method 1. Formulate a clear statement of the issue to be decided 2. Gather the scientific information related to the issue 3. List all alternative courses of action 4. Predict the positive and negative consequences of each course of action and the probability that each consequence will occur. 5. Weigh the alternatives and choose the best solution. 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 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 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 Environmental Questions and the Scientific Method Environmental sciences deal with especially complex systems. Not as neat as the scientific method Different approach has been used in environmental sciences Example: California Condor