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

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 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 E.g. 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

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.

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. Science requires not only logical reasoning but also correct premises.

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.

Inductive reasoning Generalizations based on a number of observations = inductive reasoning.

All of the male eared grebes we have seen in the breeding season have golden feathers. = All male eared grebes have golden feathers during the breeding season.

Inductive & Deductive Because science is based on observations, its conclusions are only as true as the premised from which they are deduced. Mastering the art of picking out premises and conclusions is the first step toward good analytical thinking, but we must also think about whether the premises really do support their conclusions. Deductive argument: an argument whose premises make its conclusion certain Inductive argument: an argument whose premises make its conclusion likely

Example Smith owns only blue pants and brown pants. Smith is wearing a pair of his pants today. So Smith is wearing either blue or brown pants today. This is an instance of a deductive argument. We can tell that the argument is deductive because the two premises (that is, the first two sentences) guarantee the truth of the conclusion. If the two premises really are true, then there is no possible way that the conclusion could be false.

Example The soccer game is on either Thursday or Friday. I just found out that the game is not on Thursday, So the game must be on Friday. Again, this is a deductive argument, for the truth of the premises guarantees the truth of the conclusion.

Example January has always been cold here in Siberia. Today is January 14, so it is going to be another cold day in Siberia. This argument is inductive. The premises make the conclusion likely, but they do not guarantee that the conclusion is true. To put the point another way, it is possible that the premises of this argument could be true and the conclusion could still be false. One can, for example, imagine a freak warm day in Siberia on January 14. But one cannot imagine that Smith owns only brown pants and blue pants, that he is wearing his own pants and that his pants are not brown or blue. To make the conclusion about the color of Smith s pants false, one has to make one of the premises false. But one can make the cold day in Siberia claim false while keeping the premises true.

Example The local branch of Wells Fargo was robbed yesterday. Jenny needed money to pay off her gambling debts. She just bought a gun two days ago, and I saw her hanging around the local Wachovia Bank yesterday morning. Today the bookie s goons stopped looking for Jenny. So Jenny robbed Wachovia Bank yesterday. This is the sort of inductive argument that should be familiar to anyone who has ever watched an episode of Law & Order. Again, though, as anyone who has seen Law & Order can attest, these sorts of inductive arguments can be (and frequently are) wrong. Even if all the premises are true, it is still possible that the conclusion is false.

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

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

Measurements & 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

Accuracy & Precision Accuracy refers to what we know. Precision refers to how well we measure.

Accuracy vs 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.

Observations, Facts, Inferences, & Hypotheses Observations - may be made by any of the five senses or instruments that measure beyond what we sense. Inferences - a generalization that arises from a set of obs. Facts observations 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

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

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.

Repeatability Operational definitions variables described in terms of what one would have to do to duplicate the variable s measurements. Operational definition allows other scientists to repeat experiments exactly and check results.

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

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.

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

Scientific Method 1. Draw a conclusion from the data. 2. Compare the conclusion to the hypothesis and determine whether the results support or reject the hypothesis. 3. If the hypothesis is supported, conduct additional experiments to test it further. If the hypothesis is rejected, construct a new hypothesis.

Scientific Method

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, lacks empirical evidence or based on faulty reasoning. Frontier science Ideas that may move into realm of 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. E.g. California Condor

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 too small to divide into two different study groups Captive breeding begun

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

Historical Evidence Frequency of fires in the Boundary Waters Canoe Area (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 forests.

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.

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

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.