UNDERSTANDING SCIENTIFIC EVIDENCE
Module 3: Scientific Thought and Reasoning
Overview and Learning Objectives:
"Evidence of conscious-like activity in the dying brain"
"Previously unknown electricity may power Biology"
"Rare tropical plant gains appetite for meat"
"Nanowires learn and remember like a human brain"
"Climate change to push species over abrupt tipping point"
The above are headlines from science stories posted in a single day (May 20, 2023) from a single science news website, ScienceDaily.com. These are not unlike dozens of other stories we see every week in the media reporting the latest research findings and how they may impact our lives.
According to a 2018 survey by the National Science Foundation (NSF), Americans have great confidence in science, but little understanding of the process underlying scientific research. In fact, only ~27% of American respondents indicated that they have "a clear understanding" of the term scientific study, and only ~24% were able to adequately describe a scientific study as involving something to do with testing theories or hypotheses, conducting experiments, or making systematic comparisons" (Besley and Hill, 2020).
Now that you are familiar with the basic elements of a good research study, you will learn to critically evaluate news headlines using logical reasoning based on what information is provided, what conclusions can be drawn, and knowing what the limits of scientific evidence is. You will then be able to read news stories like the ones listed above with a more critical eye. You will understand that the headlines reported by the media and the research conclusions often are not the same, and you will understand why.
References:
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Besley, J. and Hill, D. (2020). Science and Technology: Public Attitudes, Knowledge, and Interest | NSF - National Science Foundation. https://ncses.nsf.gov/pubs/nsb20207/public-familiarity-with-s-t-facts
In this last module, you will learn more about logic-based thought in scientific processes, you will be introduced to inductive and deductive reasoning while applying it to scientific processes and review; will better understand how science builds on itself to form hypotheses, theories, and laws; and will be able to clearly identify the limits of science based on what is observable and testable.
After completing this module, you will be able to:
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identify general inductive and deductive reasoning examples.
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differentiate a hypothesis from a theory from a law.
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identify whether specific questions of interest lie beyond the scope of scientific inquiry.
Overview will be converted to a video
Inductive and Deductive Reasoning
The goal of science is to seek knowledge. Curiosity and inquiry drive scientists to better understand the world and how it operates. To do this, they use two methods of logical thinking: inductive reasoning and deductive reasoning.
Inductive reasoning is a form of logical thinking that uses related observations to arrive at a general conclusion. Often referred to as bottom-up reasoning, inductive reasoning draws broad conclusions from specific observations. To better understand this, let’s look at an example of migratory birds. In this case, we could use inductive reasoning to analyze the behavior of individual birds to make a broader inference about the species as a whole. For example, if we observe multiple instances of individual birds in the region exhibiting migratory behaviors, such as preparing for long flights, following migratory routes, or leaving during certain seasons, we may infer that the bird species in that region does migrate. The general conclusion about the species' migratory behavior is based on specific observations of multiple individuals.
Conversely, deductive reasoning is a form of logical thinking that draws specific conclusions from generalized premises. Often referred to as top-down reasoning, deductive reasoning is the type of logic used in hypothesis-based science as it uses general principles to predict 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. Using a similar migratory bird example, we could use deductive reasoning to assess whether a specific bird belongs to a migratory species based on known characteristics of that species. For instance, if we know that all members of a certain bird family are migratory, and we observe a bird in the region that belongs to that family, we can deduce that the individual bird in question is also migratory. The specific conclusion about the migratory behavior of the individual bird is derived from the general principle or premise that all members of that bird family are migratory. In other words, the investigator uses a larger body of data to make a prediction for a specific scenario.
Test Your Knowledge
Use the interactive 7taps quizlet app below to test your knowledge about inductive versus deductive reasoning. To see the next question, simply click the quizlet screen.
Using Inductive and Deductive Reasoning in the Scientific Method
Both inductive and deductive reasoning play important roles in scientific investigation, allowing researchers to make informed judgments and draw conclusions based on available evidence and logical analysis. As a general rule, inductive reasoning is easier to disprove because it often lacks evidence to be universally true. In the migratory bird example above, while it's possible that all bird species in a local area migrate, it is also entirely possible that there are non-migratory birds in the area too. Conversely, deductive reasoning tends to be more reliable, assuming the background information is true, as it tests a smaller scope.
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, while hypothesis-based science, which is usually deductive, begins with a specific question or problem and a potential answer or solution that can be tested. The boundary between these two forms of study is often blurred, and most scientific endeavors combine both approaches. 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.
Building Scientific Evidence Through Hypotheses, Theories, and Laws
Through a systematic and iterative process involving observation, experimentation, data collection, analysis, and peer review, scientific research builds on the foundation of previous studies using deductive reasoning and logic. The more evidence accumulated, the more trust there is for a particular topic. A hypothesis, a theory, and a law are three distinct concepts in the scientific method, each serving a different purpose to describe the level of understanding. Let's briefly look through each concept.
A hypothesis is a proposed explanation or prediction for a specific phenomenon or set of observations. It is a tentative statement that can be tested through further investigation and experimentation. Hypotheses are typically formulated based on prior knowledge, existing theories, or observations. They serve as a starting point for scientific inquiry and provide a framework for designing and conducting experiments to gather evidence. Hypotheses can be supported or refuted based on empirical evidence, and they may evolve or be refined as more data is collected.
A scientific theory is a well-substantiated and comprehensive explanation that encompasses a broad range of observations, experiments, and evidence in a particular field of study. Theories are developed through rigorous testing, repeated experimentation, and extensive empirical support. They are considered to be the highest level of understanding in science and provide a coherent framework for explaining and predicting phenomena. Theories are based on a large body of evidence and have withstood extensive scrutiny and peer review. They are not speculative guesses, but rather robust explanations that integrate and explain a wide range of observations and experiments.
A scientific law, also known as a scientific principle or principle of nature, describes a concise statement or mathematical relationship that consistently holds true under specific conditions within a particular field of study. Laws are based on repeated and well-established observations and experiments. They summarize observed patterns or relationships in nature and are often expressed in mathematical equations or formulas. Unlike theories, laws do not provide explanations for the underlying mechanisms or causes of phenomena. Instead, they describe and predict what will happen under specific circumstances. Scientific laws are typically simpler and more focused than theories, but they still represent fundamental and reliable principles in their respective fields.
Descriminating Common Vernacular from Scientific Concepts:
Theories and Facts
A theory is not the same thing as a fact. A fact is "something that can be shown to be true, to exist, or to have happened" (Encarta World English Dictionary [New York: St. Martin's Press, 1999], 636). Facts are beyond dispute and can never be shown to be wrong, by definition. A theory, by contrast, is a descriptive model constructed to explain a large body of facts (accumulated observations). The aim of a theory is to explain general principles of cause-and-effect that will account for all of the known observations and allow predictions of future observations in similar circumstances.
Although every theory is built around a large number of supporting observations, a theory will never become an absolute fact because it is never practically possible to examine every observation related to a phenomenon. A new set of observations (facts) that are inconsistent with an existing theory may arise some time in the future. Once verified, these new observations will result in a revision of the theory to account for all the facts. In this way theories evolve to present ever clearer and more detailed descriptions of reality.
In his essay "Does Theory Ever Become Fact?" Charles Wynn uses the example of atomic theory to explain this distinction between theories and fact:
"Even though atomic theory has been able to explain the behavior of all matter studied thus far, and, even though in all samples scanned by microscopes, the existence of the postulated atoms has been verified, it must be considered at least conceivable that entities other than atoms might be discovered, particles which also explain the laws of Conservation of Mass, Constant Consumption, and Multiple Proportions. Scientific theories can never become facts, because a scientific theory deals with all instances of a phenomenon; i.e., it is a universal theory. While the behavior of all matter may indeed be explained by atomic theory, there is no way of being certain that this is the case. Such is the open-ended nature of science" (Hatton and Plouffe, eds., 62).
The Limits of Science
Ultimately, science is a way of coming to know and understand the natural universe. Using science, we have increased our understanding of nature and made dramatic improvements in the human condition. The power of science resides in its dependence on verifiable observations and its allowance for revision of theories in accordance with new information. The combination of these two components distinguishes science from all other ways of knowing and appreciating the universe that surrounds us. Yet, its dependence upon the objective (that which can be observed in the same way by two or more individuals) also defines the limits of the scientific method.
Questions Beyond Science
Many questions lie beyond the scope of science. If a question cannot be phrased as a hypothesis that can potentially be supported or falsified by available objective data, then it is not a scientific question. Consider the following questions.
Have alien spacecraft landed on Earth?
Does the position of the stars at the time of our birth determine aspects of our personalities?
Does God exist?
Should cloning of human embryos be permitted?
What is the meaning of life?
Was Da Vinci a better painter than Van Gogh was?
Pseudoscience
The first two questions above fall under the heading of "pseudoscience," a term that refers to events or phenomena that have not been verified by the scientific method, but often have many supporters. Examples include unidentified flying objects (UFOs) believed to be spacecraft from other worlds, astrology, extrasensory perception (ESP, or mind reading), reincarnation, and many others.
For a variety of reasons, none of these beliefs can be effectively investigated using the methods of science. In some cases, these beliefs rely on claims of one-time events that cannot be repeated (UFOs). In other cases, no reasonable mechanism is available to explain how something happens; therefore no cause-and-effect test can be devised (astrology, ESP). In all cases, there is no repeatable experiment one could imagine that would disprove the claims to the satisfaction of the believers (Trefil, James, and Robert M. Hazen, The Sciences an Integrated Approach, 2nd ed. [New York: John Wiley & Sons, Inc., 1998], 12-13).
To be verified, the observations made in science have to be repeatable. The problem with question 1, "Have alien spacecraft landed on Earth?" is that it is asks about a non-repeatable event. Although we could watch the skies carefully from now on (and many scientists are), we cannot go back in time to observe a spacecraft someone claims to have seen land.
On the other hand, we can use our scientific knowledge to look for and examine evidence of such an event. Something as large as spacecraft would surely leave an impression where it landed. Perhaps airport radars picked up an unusual signal. Scientists have investigated some claims of UFOs using such methods, but so far no substantiated evidence of alien spacecraft are available to support these claims. The many photos seen in UFO magazines are, by themselves, of no scientific value. There is no way to differentiate these from the special effects seen in science fiction movies. SETI, the Search for Extraterrestrial Intelligence, is an educational project dedicated to the search for scientific evidence of life on (or from) other planets. SETI has dedicated a number of years to the search for signs of extraterrestrial life and, thus far, has not found it.
Question 2 refers to astrology or the zodiac, which derives from an ancient Eastern tradition that supposes that the positions of the stars and planets at the time of a person's birth determine some aspects of personality and character, that person's zodiac sign. One problem with this idea from a scientific view is that no mechanism has been proposed to explain how the positions and the stars might have a bearing on personality formation. Thus, there is no cause-and-effect relationship to be tested. Despite this, one could still test for a correlation between specific personality traits and date of birth. So far, no reasonable evidence to support the notion of astrology exists.
Religious Questions
Question number 3 cannot be answered using the scientific method because there is no objective means available to define or to measure God. However, this is not to say that the religious traditions and ideals that enrich many people's lives are incompatible with science. James Trefil and Robert M. Hazen suggest, "There should be no conflict between the questions asked by science and those asked by religion, because they deal with different aspects of life. Conflicts arise when zealots on either side try to apply their methods to questions where those methods aren't applicable." (Trefil and Hazen, 12).
Ethical Questions and Other Subjective Questions
Science is not capable of exploring ethical questions, such as number 4 above. No experiment can determine moral right from wrong, because morality is a value judgment—it is subjectively defined. Science can only address questions that can be answered by considering objective information. Scientists themselves, like any group of people, vary considerably with regard to their moral and ethical beliefs. This is not to say that scientists should not be required to act in an ethical way. In fact, researchers must abide by a number of guidelines developed by committees on ethics to assure that certain standards are upheld.
For some of the same reasons, question 5, "What is the meaning of life?" is beyond the scope of the scientific method. This is not to say that the question is without value, or that an answer should not be sought! But it is a question that would be answered quite differently by different individuals. If your answer and my answer to this question disagree, that does not prove either of our conclusions false.
Beauty, as the saying goes, is in the eye of the beholder. Science cannot be used to measure or compare the aesthetic value of two works of art (question 6). Science cannot help us to enjoy a clever play or to laugh at a joke. Science may explain why the sky is blue, but it cannot tell us why it is beautiful—nor is it meant to.
Fortunately, a variety of disciplines apart from science are dedicated to exploring the many facets of the human experience: literature, philosophy, the Arts. These studies have a long history and occupy an essential niche in human cultures. They lend depth and significance to the human experience and enrich our personal lives. They serve as a great compliment to science, in that they stimulate and encourage development of an entirely different set of human sensibilities and values. They provide an essential counterbalance to the activities of science.
Applying the Information
Over the course of these three modules, you've gained an understanding of the scientific method, peer-review process, and basis behind scientific evidence, thought, and reasoning. Now it is time to apply this knowledge gained. For your final assignment, you will write a short paper on a statement found in current news sources, determining if the information given is routed in science or pseudoscience. To support your argument, you will justify your findings using credible sources. When you're ready to get started, you can access the full description of instructions by clicking the button below.