1.3: The Nature of Science
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Unit 1.3 - The Nature of Science
- Please read and watch the following Learning Resources
- Reading the material for understanding, and taking notes during videos, will take approximately 2.5 hours.
- Optional Activities and Resources are embedded.
- Bolded terms are located at the end of the unit in the Glossary. There is also a Unit Summary at the end of the Unit.
- To navigate to Unit 1.4, use the Contents menu at the top of the page OR the right arrow on the side of the page.
- If on a mobile device, use the Contents menu at the top of the page OR the links at the bottom of the page.
- Use strategies of scientific inquiry to evaluate information, problems, and the validity of science;
- Model the scientific method;
- Compare inductive reasoning with deductive reasoning;
- Compare and contrast observational and descriptive studies;
The Process of Science
Biology is a science, but what exactly is science? What does the study of biology share with other scientific disciplines? Science (from the Latin scientia, meaning “knowledge”) can be defined as a process that uses evidence, logic, and creativity to discover and explain natural and physical phenomenon while avoiding bias. The scientific method is a method of research with defined steps that include experiments and careful observation.
The steps of the scientific method will be examined in detail later, but one of the most important aspects of this method is the testing of hypotheses by means of repeatable experiments. A hypothesis is a suggested explanation for an event, which can be tested. Although using the scientific method is inherent to science, it is inadequate in determining what science is. It is relatively easy to apply the scientific method to disciplines such as physics and chemistry, but for disciplines like paleontology and geology, the scientific method is adapted to the field of study.
These areas of study are still sciences, however. Consider paleontology—even though one cannot perform repeatable experiments, hypotheses may still be supported. For instance, a paleontologist can hypothesize that an ancient organism existed based on finding a fossil. Further hypotheses could be made about various characteristics of this fossil, and these hypotheses may be found to be correct or false through continued support or contradictions from other findings. A hypothesis may become a theory with time and evidence. A theory is a well-tested and confirmed explanation for observations or phenomena. Science may be better defined as fields of study that attempt to comprehend the physical and natural underpinnings of the universe.
This 10-minute video provides an overview of the process of science.
Question after watching: What additional characteristics/steps has this video proposed is important in the scientific process that was not mentioned in the text above?
Natural Sciences
What would you expect to see in a museum of natural sciences? Frogs? Plants? Dinosaur skeletons? Exhibits about how the brain functions? A planetarium? Gems and minerals? Or, maybe all of the above? Science includes such diverse fields as astronomy, biology, computer sciences, geology, logic, physics, chemistry, and mathematics (Figure \(\PageIndex{1}\)). However, those fields of science related to the physical world and its phenomena and processes are considered natural sciences. Thus, a museum of natural sciences might contain any of the items listed above.
There is no complete agreement when it comes to defining what the natural sciences include, however. For some experts, the natural sciences are astronomy, biology, chemistry, earth science, and physics. Other scholars choose to divide natural sciences into life sciences, which study living things and include biology, and physical sciences, which study nonliving matter and include astronomy, geology, physics, and chemistry. Some disciplines such as biophysics and biochemistry build on both life and physical sciences and are interdisciplinary. Natural sciences often rely on the use of quantitative, or numeric, data although some may use qualitative, or non-numeric, data to support findings.
Not surprisingly, the natural science of biology has many branches or subdisciplines. Cell biologists study cell structure and function, while biologists who study anatomy investigate the structure of an entire organism. Those biologists studying physiology, however, focus on the internal functioning of an organism. Some areas of biology focus on only particular types of living things. For example, botanists explore plants, while zoologists specialize in animals.
This 5-minute video provides the purpose of the scientific method.
Question after watching: Charles Molnar describes many ways in which human biases can influence how we observe or interpret the world around us. What steps do scientists put in place to try to remove these human biases from the process of learning about the world so that the final findings are as objective as possible?
History of Biological Science
Although modern biology is a relatively recent development, sciences related to and included within it have been studied since ancient times. Natural philosophy was studied as early as the ancient civilizations of Mesopotamia, Egypt, the Indian subcontinent, and China. However, the origins of modern biology and its approach to the study of nature are most often traced back to ancient Greece. (Biology is derived from the Greek word "bio" meaning "life" and the suffix "ology" meaning "study of.")
The scientific method was used in ancient times, but it was first documented by England’s Sir Francis Bacon (1561–1626), who set up the first methodology for scientific inquiry. The scientific method is not exclusively used by biologists but can be applied to almost all fields of study as a logical, rational problem-solving method. Natural history observations and advances in microscopy have also had a profound impact on biological thinking. In the early 19th century, a number of biologists pointed to the central importance of the cell and in 1838, Schleiden and Schwann began promoting the now universal ideas of the cell theory. Jean-Baptiste Lamarck was the first to present a coherent theory of evolution, although it was the British naturalist Charles Darwin who spread the theory of natural selection throughout the scientific community. In 1953, the discovery of the double-helical structure of DNA marked the transition to the era of molecular genetics.
Learn about Karl Popper and falsifiable hypotheses in this 11-minute video.
Question after watching: How does the idea of falsification change how you may have learned about science in the past?
Scientific Reasoning
One thing is common to all forms of science: an ultimate goal “to know.” Curiosity and inquiry are the driving forces for the development of science. Scientists seek to understand the world and the way it operates. To do this, they use two methods of logical thinking: inductive reasoning and deductive reasoning (Figure \(\PageIndex{2}\)).
Inductive reasoning is a form of logical thinking that uses related observations to arrive at a general conclusion. This type of reasoning is common in descriptive science. A life scientist such as a biologist makes observations and records them. These data can be qualitative or quantitative, and the raw data can be supplemented with drawings, pictures, photos, or videos. From many observations, the scientist can infer conclusions (inductions) based on evidence. Inductive reasoning involves formulating generalizations inferred from careful observation and the analysis of a large amount of data. Brain studies provide an example. In this type of research, many live brains are observed while people are doing a specific activity, such as viewing images of food. The part of the brain that “lights up” during this activity is then predicted to be the part controlling the response to the selected stimulus, in this case, images of food. Then, researchers can stimulate that part of the brain to see if similar responses result.
Deductive reasoning or deduction is the type of logic used in hypothesis-based science. In deductive reason, the pattern of thinking moves in the opposite direction as compared to inductive reasoning. Deductive reasoning is a form of logical thinking that uses a general principle or law to forecast specific results. From those general principles, a scientist can extrapolate and predict the specific results that would be valid as long as the general principles are valid. Studies in climate change can illustrate this type of reasoning. For example, scientists may predict that if the climate becomes warmer in a particular region, then the distribution of plants and animals should change. These predictions have been made and tested, and many such changes have been found, such as the modification of arable areas for agriculture, with change based on temperature averages.
Decide if each of the following is an example of inductive or deductive reasoning.
- All flying birds and insects have wings. Birds and insects flap their wings as they move through the air. Therefore, wings enable flight.
- Insects generally survive mild winters better than harsh ones. Therefore, insect pests will become more problematic if global temperatures increase.
- Chromosomes, the carriers of DNA, separate into daughter cells during cell division. Therefore, DNA is the genetic material.
- Animals as diverse as humans, insects, and wolves all exhibit social behavior. Therefore, social behavior must have an evolutionary advantage.
- Answer
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1: inductive; 2: deductive; 3: deductive; 4: inductive.
Many students confuse deductive reasoning with inductive reasoning and vice versa. Learn the difference in this 3-minute video.
Question after watching: Reflect on incidents/events in your life where you applied deductive and inductive reasoning. Describe them and why they are instances of inductive and deductive reasoning.
Both types of logical thinking are related to the two main pathways of scientific study: descriptive science and hypothesis-based science. Descriptive (or discovery) science, which is usually inductive, aims to observe, explore, and discover. Hypothesis-based science, which is usually deductive, begins with a specific question or problem and a potential answer or solution that can be tested. In hypothesis-based science, specific results are predicted from a general premise.
The boundary between descriptive science and hypothesis-based science is often blurred, and most scientific endeavors combine both approaches. Inductive and deductive reasoning are often used in tandem to advance scientific knowledge. The fuzzy boundary becomes apparent when thinking about how easily observation can lead to specific questions. For example, a gentleman in the 1940s observed that the burr seeds that stuck to his clothes and his dog’s fur had a tiny hook structure. On closer inspection, he discovered that the burrs’ gripping device was more reliable than a zipper. He eventually developed a company and produced the hook-and-loop fastener popularly known today as Velcro. Descriptive science and hypothesis-based science are in continuous dialogue.
The Scientific Method
Biologists study the living world by posing questions about it and seeking science-based responses. This approach is common to other sciences as well and is often referred to as the scientific method. The scientific process typically starts with an observation (often a problem to be solved) that leads to a question. Let’s think about a simple problem that starts with an observation and apply the scientific method to solve the problem. One Monday morning, a student arrives at class and quickly discovers that the classroom is too warm. That is an observation that also describes a problem: the classroom is too warm. The student then asks a question: “Why is the classroom so warm?”
Learn about the 5 criteria that a testable question should meet in this 7.5-minute video.
Read the following questions. Does the statement lend itself to investigation using the scientific method? In other words, is the hypothesis falsifiable (can be proven false)?
- Is macaroni and cheese tastier than broccoli soup?
- Are hummingbirds attracted to the color red?
- Is the moon made out of green cheese?
- Is plagiarism dishonest?
- Questions 1 and 2 are subjective and cannot be disproven using scientific method. Questions 3 and 4 can be tested using scientific method.
- Questions 3 and 4 are subjective and cannot be disproven using scientific method. Questions 1 and 2 can be tested using scientific method.
- Questions 1 and 3 are subjective and cannot be disproven using scientific method. Questions 2 and 4 can be tested using scientific method.
- Questions 1 and 4 are subjective and cannot be disproven using scientific method. Questions 2 and 3 can be tested using scientific method.
- Answer
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d. Questions 1 and 4 are subjective and cannot be disproven using scientific method. Questions 2 and 3 can be tested using scientific method.
Proposing a Hypothesis
Recall that a hypothesis is a suggested explanation that can be tested. To solve a problem, several hypotheses may be proposed. For example, one hypothesis might be, “The classroom is warm because no one turned on the air conditioning.” But there could be other responses to the question, and therefore other hypotheses may be proposed. A second hypothesis might be, “The classroom is warm because there is a power failure, and so the air conditioning doesn’t work.”
Once a hypothesis has been selected, the student can make a prediction. A prediction is similar to a hypothesis but it typically has the format “If . . . then . . . .” For example, the prediction for the first hypothesis might be, “If the student turns on the air conditioning, then the classroom will no longer be too warm.”
In this 7-minute video, learn the difference between a fact, a theory, a hypothesis, and a scientific law.
Question BEFORE and AFTER watching: How would you define hypothesis and theory?
Testing a Hypothesis
A valid hypothesis must be testable. It should also be falsifiable, meaning that it can be disproven by experimental results. Importantly, science does not claim to “prove” anything because scientific understandings are always subject to modification with further information. This step—openness to disproving ideas—is what distinguishes sciences from non-sciences. The presence of the supernatural, for instance, is neither testable nor falsifiable. To test a hypothesis, a researcher will conduct one or more experiments designed to eliminate one or more of the hypotheses. Each experiment will have one or more variables and one or more controls. A variable is any part of the experiment that can vary or change during the experiment. The control group contains all of the same conditions experimental group EXCEPT for the variable being tested. Therefore, if the results of the experimental group differ from the control group, the difference must be due to the manipulation, rather than some outside factor. Identify the variables and controls in the examples from the section above.
Revisit the hypotheses from the section above:
- The classroom is warm because no one turned on the air conditioning.
- The classroom is warm because there is a power failure, and so the air conditioning doesn’t work.
To test the first hypothesis, the student would find out if the air conditioning is on. If the air conditioning is turned on but does not work, there should be another reason, and this hypothesis should be rejected. To test the second hypothesis, the student could check if the lights in the classroom are functional. If so, there is no power failure and this hypothesis should be rejected. Each hypothesis should be tested by carrying out appropriate experiments. Be aware that rejecting one hypothesis does not determine whether or not the other hypotheses can be accepted; it simply eliminates one hypothesis that is not valid (Figure \(\PageIndex{4}\)). Using the scientific method, the hypotheses that are inconsistent with experimental data are rejected.
While this “warm classroom” example is based on observational results, other hypotheses and experiments might have clearer controls. For instance, a student might attend class on Monday and realize she had difficulty concentrating on the lecture. One observation to explain this occurrence might be, “When I eat breakfast before class, I am better able to pay attention.” The student could then design an experiment with a control to test this hypothesis, including keeping all details of their morning the same but eating breakfast one day versus another to see how their attention holds in class.
The scientific method may seem too rigid and structured (Figure \(\PageIndex{3}\)). It is important to keep in mind that, although scientists often follow this sequence, there is flexibility. In fact, the scientific process is much more complex in practice. Sometimes an experiment leads to conclusions that favor a change in approach; often, an experiment brings entirely new scientific questions to the puzzle. Many times, science does not operate in a linear fashion; instead, scientists continually draw inferences and make generalizations, finding patterns as their research proceeds. Scientific reasoning is more complex than the scientific method alone suggests. Notice, too, that the scientific method can be applied to solving problems that aren’t necessarily scientific in nature.
In this 5-minute video, explore how scientists designed and implemented a sampling and data collection plan to answer scientific questions.
Question after watching: What are important things to consider when selecting samples?
In this 6-minute video, explore why data is critically important to the scientific process, what makes good data, and how to use data correctly.
Question after watching: What is the distinction and/or relationship between variables and data?
In the example below, the scientific method is used to solve an everyday problem. Order the scientific method steps (numbered items) with the process of solving the everyday problem (lettered items). Based on the results of the experiment, is the hypothesis correct? If it is incorrect, propose some alternative hypotheses.
- Observation
- Question
- Hypothesis (answer)
- Prediction
- Experiment
- Result
- There is something wrong with the electrical outlet.
- If something is wrong with the outlet, my coffeemaker also won’t work when plugged into it.
- My toaster doesn’t toast my bread.
- I plug my coffee maker into the outlet.
- My coffeemaker works.
- Why doesn’t my toaster work?
- Answer
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1: C; 2: F; 3: A; 4: B; 5: D; 6: E. The original hypothesis is incorrect, as the coffeemaker works when plugged into the outlet. Alternative hypotheses include that the toaster might be broken or that the toaster wasn't turned on.
In this 6-minute video, the critical importance of mathematical models to the scientific process is explored.
Question: Why is modeling such a fundamentally important tool?
Discover why collaboration among scientists with different backgrounds and expertise is essential for strong science investigations in this 6.5-minute video.
Question after watching: The research expedition includes several research teams. Why is that?
See how science REALLY works in this 5-minute video.
Question after watching: Why do they use the pinball game analogy for describing how science works?
Find a more realistic, but more complex, diagram of the scientific method from the University of California - Berkeley here: https://undsci.berkeley.edu/lessons/pdfs/complex_flow_handout.pdf
Pseudoscience
Pseudoscience is a claim, belief, or practice that is presented as scientific but does not adhere to the standards and methods of science. True science is based on repeated evidence-gathering and testing of falsifiable hypotheses. Pseudoscience does not adhere to these criteria. Pseudoscience is often known as fringe or alternative science. It usually lacks the carefully-controlled and thoughtfully-interpreted experiments which provide the foundation of the natural sciences and which contribute to their advancement. In addition to phrenology, some other examples of pseudoscience include astrology, extrasensory perception (ESP), reflexology, reincarnation, and Scientology
Characteristics of Pseudoscience
Whether a field is actually science or just pseudoscience is not always clear. However, pseudoscience generally exhibits certain common characteristics. Indicators of pseudoscience include:
- The use of vague, exaggerated, or untestable claims: Many claims made by pseudoscience cannot be tested with evidence. As a result, they cannot be falsified, even if they are not true.
- An over-reliance on confirmation rather than refutation: Any incident that appears to justify a pseudoscience claim is treated as proof of the claim. Claims are assumed true until proven otherwise, and the burden of disproof is placed on skeptics of the claim.
- A lack of openness to testing by other experts: Practitioners of pseudoscience avoid subjecting their ideas to peer review. They may refuse to share their data and justify the need for secrecy with claims of proprietary or privacy.
- An absence of progress in advancing knowledge: In pseudoscience, ideas are not subjected to repeated testing followed by rejection or refinement, as hypotheses are in true science. Ideas in pseudoscience may remain unchanged for hundreds — or even thousands — of years. In fact, the older an idea is, the more it tends to be trusted in pseudoscience.
- Personalization of issues: Proponents of pseudoscience adopt beliefs that have little or no rational basis, so they may try to confirm their beliefs by treating critics as enemies. Instead of arguing to support their own beliefs, they attack the motives and character of their critics.
- The use of misleading language: Followers of pseudoscience may use scientific-sounding terms to make their ideas sound more convincing. For example, they may use the formal name dihydrogen monoxide to refer to plain old water.
This 3.5-minute video reviews what is considered pseudoscience.
Question after watching: What are some instances of pseudoscience that you have seen or heard recently?
Persistence of Pseudoscience
Despite failing to meet scientific standards, many pseudosciences survive. Some pseudosciences remain very popular with large numbers of believers. A good example is astrology.
Astrology claims to study the movements and relative positions of celestial objects as a means for divining information about human affairs and terrestrial events. Many ancient cultures attached importance to astronomical events, and some developed elaborate systems for predicting terrestrial events from celestial observations. Throughout most of its history in the West, astrology was actually considered a scholarly tradition and was common in academic circles. With the advent of modern Western sciences and the process of scientific inquiry, however, astrology was called into question. It was challenged on both theoretical and experimental grounds. Eventually, astrology was shown to have no scientific validity or explanatory power.
Today, astrology is considered a pseudoscience, yet it continues to have many devotees. Many people know their astrological sign, and some are familiar with the supposed personality traits associated with their "sign". Astrological readings and horoscopes are readily available online and in print media, and a lot of people read them, even if only occasionally. Some believe that astrology is scientific. Studies suggest that the persistent popularity of pseudosciences such as astrology is due to misunderstandings of scientific principles and methodology. Alternatively, some are not convinced by scientific arguments that go against their personal beliefs and this, in the end, can do real harm to themselves or others.
Dangers of Pseudoscience
Belief in astrology is unlikely to cause a person harm, but belief in some other pseudosciences might — especially in healthcare-related areas. Treatments that seem scientific but are not may be ineffective, expensive, and even dangerous to patients. Seeking out pseudoscientific treatments may also delay or preclude patients from seeking scientifically-based medical treatments that have been tested and found safe and effective. In short, following pseudoscience instead of established health care practices may be harmful.
Scientific Hoaxes, Frauds, and Fallacies
Pseudoscience is not the only way that science may be misused. Scientific hoaxes, frauds, and fallacies may misdirect the pursuit of science, put patients at risk, or mislead and confuse the public. An example of each of these misuses of science and its negative effects is described below.
The Vaccine-Autism Fraud
While it is not true, you may have heard that certain vaccines put the health of young children at risk. This persistent idea is not supported by scientific evidence or accepted by the vast majority of experts in the field. It stems largely from an elaborate medical research fraud that was reported in a 1998 article published in the respected British medical journal, The Lancet. The main author of the article was a British physician named Andrew Wakefield. In the article, Wakefield and his colleagues described case histories of only 12 children, most of whom were reported to have developed autism soon after the administration of the MMR (measles, mumps, rubella) vaccine.
There were a whole host of problems with this study, including falsification of research, ethics violations, and experimental design problems. The paper has been retracted (a very big deal in the science community), most of the co-authors have retracted their authorship, and Wakefield lost his medical license. It also later emerged that Wakefield had received research funding from a group of people who were suing vaccine manufacturers. Thousands of follow-up studies have failed to show any association between the MMR vaccine and autism. Unfortunately, by then, the damage had already been done. Parents afraid that their children would develop autism had refrained from having them vaccinated. British MMR vaccination rates fell from nearly 100 percent to 80 percent in the years following the study. The consensus of medical experts today is that Wakefield’s fraud put hundreds of thousands of children at risk because of the lower vaccination rates and also diverted research efforts and funding away from finding the true cause of autism.
Correlation-Causation Fallacy
Many statistical tests used in scientific research calculate correlations between variables. Correlation refers to how closely related two data sets are, which may be a useful starting point for further investigation. Correlation, however, is also one of the most misused types of evidence, primarily because of the logical fallacy that correlation implies causation. In reality, just because two variables are correlated does not necessarily mean that either variable causes the other.
A few simple examples, illustrated by the graphs below, can be used to demonstrate the correlation-causation fallacy. Assume a study found that both per capita consumption of mozzarella cheese and the number of Civil Engineering doctorates awarded are correlated; that is, rates of both events increase together Figure \(\PageIndex{4}\). If correlation really did imply causation, then you could conclude from the second example that the increase in age of Miss America causes an increase in murders of a specific type or vice versa Figure \(\PageIndex{5}\).
Watch this 4-minute video to learn how to spot a misleading graph.
Question after watching: How can graphs present an opinion?
HRT and CHD
An actual example of the correlation-causation fallacy occurred during the latter half of the 20th century. Numerous studies showed that women taking hormone replacement therapy (HRT) to treat menopausal symptoms also had a lower-than-average incidence of coronary heart disease (CHD). This correlation was misinterpreted as evidence that HRT protects women against CHD. Subsequent studies that controlled other factors related to CHD disproved this presumed causal connection. The studies found that women taking HRT were more likely to come from higher socio-economic groups, with better-than-average diets and exercise regimens. Rather than HRT causing lower CHD incidence, these studies concluded that HRT and lower CHD were both effects of higher socio-economic status and related lifestyle factors.
How statistics can be misleading
Question after watching: What types of motivation could be at play when people or organizations present statistics?
Finally, read through this “Rough Guide to Spotting Bad Science” infographic from Compound Interest:
