After completing this chapter, you will be able to
- Describe the nature of science and its usefulness in explaining the natural world.
- Distinguish among facts, hypotheses, and theories.
- Outline the methodology of science, including the importance of tests designed to disprove hypotheses.
- Discuss the importance of uncertainty in many scientific predictions, and the relevance of this to environmental controversies.
The Nature of Science
Science is a way of knowing about the world around us. Environmental science focuses on gaining an understanding of how the environment, with all of its biotic (living) and abiotic (non-living) components, functions as well as how humans impact it or are impacted by it. In other words, our actions may alter the environment in a way that impacts us, such as when we pollute water through our industrial activities and later discover that there are health implications that arise from being exposed to or consuming that polluted water.
The broad goals of science are to understand natural phenomena and to explain how they may be changing over time. To achieve these goals, scientists carefully observe natural phenomena and conduct experiments.
All science begins with observation, so a keen sense of awareness is the primary tool of the scientist. Some science is purely observational in nature and is often referred to as descriptive science. To learn more about how the environment functions, scientists often rely on the scientific method.
Scientific investigations may be pure or applied. Pure science is driven by intellectual curiosity – it is the unfettered search for knowledge and understanding, without regard for its usefulness in human welfare. Applied science is more goal-oriented and deals with practical difficulties and problems of one sort or another. Applied science might examine how to improve technology, or to advance the management of natural resources, or to reduce pollution or other environmental damages associated with human activities.
The Scientific Method
Most of us are already familiar with the scientific method because it closely mirrors the thought process we undergo in solving a problem. Let’s say for example that you have a coffee maker that operates on a timer and that you are used to waking up in the morning to the smell of brewed coffee. One day you awake to find that although you set the timer the night before, there is no coffee in the pot. That observation is the very first step in beginning to solve a problem and it is also the very beginning of employing the scientific method.
Next, your mind may jump to the question of why the coffee maker did not make the coffee. You may then begin to search for a solution. Here is where the scientific method slows down a bit. While you may immediately think, did I forget to put water in the coffee maker? The scientific method is going to take this step by step. The first step is going to be to develop a hypothesis, or a proposed explanation (there is no coffee because there is no water in the machine). A prediction based on the hypothesis is then generated (adding water to the coffee maker will solve the problem). And finally, this prediction is tested (add water to the coffee maker to determine if that was the problem).
The results generated by applying the scientific method are then used to refine the process and narrow down the number of possible explanations. If there was water in the coffee maker all along, and adding water did not solve the problem, then the hypothesis is not supported and a new hypothesis is proposed. If, however, adding water gets you the coffee you have been waiting for, then your hypothesis is supported and your problem solved. In the world of science, this would not be the end of the application of the scientific method, because there is always more to learn. When studying the world around us, we always strive to build large bodies of evidence so experiments are generally replicated as a means of making for more robust conclusions.
Facts, Hypotheses, and Experiments
A fact is an event or thing that is definitely known to have happened, to exist, and to be true. Facts are based on experience and scientific evidence. In contrast, a hypothesis is a proposed explanation for the occurrence of a phenomenon. Scientists formulate hypotheses as statements and then test them through experiments and other forms of research. Hypotheses are developed using logic, inference, and mathematical arguments in order to explain observed phenomena. However, it must always be possible to refute a scientific hypothesis. Thus, the hypothesis that “cats are so intelligent that they prevent humans from discovering it” cannot be logically refuted, and so it is not a scientific hypothesis.
A theory is a broader conception that refers to a set of explanations, rules, and laws. These are supported by a large body of observational and experimental evidence, all leading to robust conclusions. It is important to note that the term 'theory' is used differently in science than in common language. What people generally mean then they say they have a 'theory' is that they have an idea. This most closely resembles a scientific hypothesis. In science, theories are widely supported and accepted. The following are some of the most famous theories in science:
- the theory of gravitation, first proposed by Isaac Newton (1642-1727)
- the theory of evolution by natural selection, published simultaneously in 1858 by two English naturalists, Charles Darwin (1809-1882) and Alfred Russel Wallace (1823-1913)
- the theory of relativity, identified by the German–Swiss physicist, Albert Einstein (1879-1955)
Celebrated theories like these are strongly supported by large bodies of evidence, and they will likely persist for a long time. However, we cannot say that these (or any other) theories are known with certainty to be true –some future experiments may yet falsify even these famous theories. Thus, science is always considered to be provisional.
The scientific method is only used to investigate questions that can be critically examined through observation and experiment. Consequently, science cannot resolve value-laden questions, such as the meaning of life.
An experiment is a test or investigation that is designed to provide evidence in support of, or preferably against, a hypothesis. A natural experiment is conducted by observing actual variations of phenomena in nature, and then developing explanations by analysis of possible causal mechanisms. A manipulative experiment involves the deliberate alteration of factors that are hypothesized to influence phenomena. The manipulations are carefully planned and controlled in order to determine whether predicted responses will occur, thereby uncovering causal relationships. In a manipulative experiment, there are two types of variables. The first is the variable that is altered by the scientist in order to ascertain its effect. this is called the independent variable. The second is the variable that was measured in order to see what the effect was - the dependent variable.
By far the most useful working hypotheses in scientific research are designed to disprove rather than support. Thus, null hypotheses are often formulated to enhance our progress toward understanding a particular phenomenon. A null hypothesis is a specific testable investigation that denies something implied by the main hypothesis being studied. Unless null hypotheses are eliminated on the basis of contrary evidence, we cannot be confident of the main hypothesis.
To demonstrate this point, we will draw an example from a philosopher named Karl Popper (1902-1994). Let’s suppose that we have observed that every swan we have ever seen in nature has been white. Since we are trying to build on our scientific understanding of biodiversity, we can propose the hypothesis that ‘all swans are white’ and set about testing it. In order to validate our hypothesis, we can begin looking in all of the lakes and ponds where we would expect to see swans and take observational data, counting the number of swans and noting their color. The limitation in terms of science is that no matter how many white swans we encounter, we will never have proven that all swans are white, because we must always be open to the possibility that there is a swan of another color out there. Some of you are right now thinking, aren’t some swans black? Indeed they are. And how many black swans did we need to observe to prove our hypothesis wrong?
There are two take-home messages in this story. The first is that science does not progress by proving itself right, as many suppose. Observing one more white swan does not really add substantially to our body of knowledge. We do, however, learn something useful by proving ourselves wrong. A single black swan observation disproved our hypothesis.
The next message is that even if we didn’t see that black swan, we need to be open to there being one somewhere in the world. As evidence is accumulated for a given explanation, our confidence in that conclusion grows, but it will never reach one hundred percent. In fact, scientists generally cannot claim anything is one hundred percent certain. The public has been misled by the claim in the past, as when a scientist was asked if he was one hundred percent certain that climate change was caused by humans. This is the reason why, even when a strong body of evidence, absolute certainty is not possible.
Statistical tests are often invoked to assess this level of certainty, thus relieving the scientist from making a judgement, which may open the door to bias.
This is an important aspect of scientific investigation. For instance, a particular hypothesis might be supported by many confirming experiments or observations. This does not, however, serve to “prove” the hypothesis – rather, it only supports its conditional acceptance. As soon as a clearly defined hypothesis is falsified by an appropriately designed and well-conducted experiment, it is disproved for all time. This is why experiments designed to disprove hypotheses are a key aspect of the scientific method.
Principles of Scientific Inquiry
In the world of science, research and conclusions are held to very high standards. Scientific research must undergo peer review before it can be published. During this process, experts in the specific field subject the research findings to an exhaustive review to ensure that the research is properly conducted, the results are accurate, and that the conclusions are justified. As a result, published science is considered to be a very reliable source of information.
Another characteristic of science is that it should be unbiased. Researchers should not let vested interests guide their research endeavors or conclusions. This is an area in which complications often arise. Researchers, even when they are employed at public research institutions, often must solicit funding to pursue their research projects from government agencies or private donors (often corporations). One the one hand, in order to get funded, they must cater their research to the interests of the funding agencies, and further, they may fear that if their results are not in the interest of their donors, they may lose funding. One might imagine that a chemical corporation that makes large donations to a university would not appreciate a researcher from that institution publishing a study showing that the chemicals manufactured by that company are linked to cancer.
One way that researchers avoid bias is through transparency. Scientific studies that are published generally consist of four separate sections: In Introduction, Methods, Results and Conclusion or Discussion. The Methods section includes an exhaustive account of how the study as conducted so that other researchers can replicate the study as a means of verifying or contradicting the results. The Results section includes the findings of the study, or in graphic or tabular form. This allows readers to ascertain what the basis is for the conclusions that were drawn in the study.
When science undergoes rigorous peer review, the publications are considered to be a primary resource and are considered to carry a significant amount of authority. Most of the public, however, has very little exposure to these resources. You will not find them in bookstores or at community libraries for the most part. To access them directly, you generally need to have access to a college or university library, where they are often available as digital resources. Alternatively, you may subscribe to them directly, but they are generally not free.
How is scientific information disseminated to the public then? Usually by way of secondary literature. These are magazines, newspapers or websites that report on new advances in science. While they are often quite accurate, they are not as authoritative because they are not written by the expert in the field and do not undergo peer review. Within this category, there are also a number of publications that are demonstrably inaccurate and misleading. This places the burden of developing a very discerning eye for what constitutes an accurate portrayal of scientific information on the general public. Some questions to ask are, is this a publication or website that I am familiar with and that I know to be reputable? Does it have a thorough list of references that I can refer to? Is the author a reputable figure in the field? Keep in mind that the internet has no constraints on the factual nature of what can be posted, and the resources that appear first when you conduct a search are not necessarily the most accurate ones.
Government agencies and research bodies may also be reliable sources of information, but they are prone to the same pitfalls and biases as other realms of science. In essence, the political climate at a given time may impact the presentation of information. While government reports are often posted online for public consumption, they have not necessarily undergone peer review.
It is always a good idea to approach information, particularly when it relates to an issue that is either contentious or political in nature with a healthy bit of skepticism. One advantage of achieving a working level of scientific literacy is that it qualifies you to be a discerning judge of the validity of the information you read.
The procedures and methods of science are important in the identifying, understanding, and resolving environmental problems. At the same time, however, social and economic issues are also vital considerations. Although science has made tremendous progress in helping us to understand the natural world, the extreme complexity of biology and ecosystems makes it difficult for environmental scientists to make reliable predictions about the consequences of many human economic activities and other influences. This context underscores the need for continued study of the scientific and socio-economic dimensions of environmental problems, even while practical decisions must be made to deal with obvious issues as they arise.
Questions for Review
- Outline the reasons why science is a rational way of understanding the natural world.
- Why are null hypotheses an efficient way to conduct scientific research? Identify a hypothesis that is suitable for examining a specific problem in environmental science and suggest a corresponding null hypothesis that could be examined through research.
Questions for Discussion
- What are the key differences between science and a less objective belief system, such as religion?
- What factors result in scientific controversies about environmental issues? Contrast these with environmental controversies that exist because of differing values and world views.
- Many natural phenomena are highly variable, particularly ones that are biological or ecological. What are the implications of this variability for understanding and predicting the causes and consequences of environmental changes? How do environmental scientists cope with this challenge of a variable natural world?
- Devise an environmental question of interest to yourself. Suggest useful hypotheses to investigate, identify the null hypotheses, and outline experiments that you might conduct to provide answers to this question.
- During a research project investigating mercury, an environmental scientist performed a series of chemical analyses of fish caught in Lake Canuck. The sampling program involved seven species of fish obtained from various habitats within the lake. A total of 360 fish of various sizes and sexes were analyzed. It was discovered that 30% of the fish had residue levels greater than 0.5 ppm of mercury, the upper level of contamination recommended by Health Canada for fish eaten by humans. The scientist reported these results to a governmental regulator, who was alarmed by the high mercury residues because of Lake Canuck’s popularity as a place where people fish for food. The regulator asked the scientist to recommend whether it was safe to eat any fish from the lake or whether to avoid only certain sizes, sexes, species, or habitats. What sorts of data analyses should the scientist perform to develop useful recommendations? What other scientific and non-scientific aspects should be considered?
References Cited and Further Reading
American Association for the Advancement of Science (AAAS). 1990. Science for All Americans. AAAS, Washington, DC.
Barnes, B. 1985. About Science. Blackwell Ltd ,London, UK.
Giere, R.N. 2005. Understanding Scientific Reasoning. 5th ed. Wadsworth Publishing, New York, NY.
Kuhn, T.S. 1996. The Structure of Scientific Revolutions. 3rd ed. University of Chicago Press, Chicago, IL.
McCain, G. and E.M. Siegal. 1982. The Game of Science. Holbrook Press Inc., Boston, MA.
Moore, J.A. 1999. Science as a Way of Knowing. Harvard University Press, Boston, MA.
Popper, K. 1979. Objective Knowledge: An Evolutionary Approach. Clarendon Press, Oxford, UK.
Raven, P.H., G.B. Johnson, K.A. Mason, and J. Losos. 2013. Biology. 10th ed. McGraw-Hill, Columbus, OH.
Silver, B.L. 2000. The Ascent of Science. Oxford University Press, Oxford, UK.