A Gentle Reminder that a Hypothesis is Never Proven Correct, nor is a Theory Ever Proven to Be True By Jacqueline McLaughlin
onald French, president of the don’t always work in practice. Among ing why or how things happen. For Society of College Science some scientists, theories are thought to example, “global warming” refers to DTeachers, points out in his lack solid basis in the facts (Morrison the observation that worldwide tem- recent commentary on disclaimers in 2005, p. 39). peratures seem to be increasing. The science textbooks that science is typi- Yet, the scientific definition of “theory of global warming” refers to cally taught as a litany of terms and a theory is a logical self-consistent scientific work that attempts to explain facts using textbooks that do not stress model or framework for describing how and why this could be happening that the concepts presented in them are the behavior of a certain natural by measuring various factors such as
actually theories—the best current ex- phenomenon that is supported by increased CO2 emissions in the atmo- planations supported by experimental considerable experimental evidence sphere, loss of rain forest productivy in evidence that scientists have to offer (www.wikipedia.org). tropical ecosystems, and ice sedimen- (2006). We teachers, therefore, have While most scientists try to rely tation in Antarctica and Greenland. created a huge misconception for on the dictionary definition of a scien- “Skeletal muscle contraction” refers to students and non-scientists who read tific theory, Thomas Lovejoy, environ- the observation that muscles shorten, and use textbooks. They have come mental scientist, author, and president as seen using microscopy, when myo- to believe that science is absolute and of the Heinz Center for Science, cytes or sarcomeres are stimulated. The not open to challenge. Worse still for Economics and the Environment, “sliding filament theory of skeletal the scientific community is the fact says that “theory is used in everyday muscle contraction” refers to the body that, in common speech, theory has English to mean hypothesis whereas of scientific experimental evidence that almost the opposite meaning from its in science it means something much explains how the proteins actin and use in the sciences. This change can stronger and just shy of a law (e.g., myosin—with the aid of other proteins be seen in modern dictionaries that Second Law of Thermodynamics). like troponin and tropomyosin, essen- now define theory as a guess or hunch Theory in science means a constantly tial ions like Ca2+, and molecules like in preference to the scientific defini- tested explanation of a broad variety ATP—in the sarcomere work to ‘slide’ tion. In everyday English, a theory is of facts and phenomena.” past one another to shorten the H-zone a hunch that a detective comes up with Richard B. Alley, an eminent and I-bands. No hunches here, just in a murder mystery. It is one of several scientist at Penn State University solid data from countless published competing ideas, none of them proved. known for his work in global warm- scientific experiments that continue to Fringe theories and conspiracy theories ing, states that “in contrast to most support the best explanation thus far. are crazy ideas that are out of the main- dictionary definitions, I believe that These two theories have passed the stream. New medicines or changes in theories necessarily involve narrative test of time, as have hundreds others the tax laws may be good in theory, but as well as explanation and prediction. like chemiosmosis as the basis of ATP So, you might define a theory as the synthesis, voltage-gated ion channels overarching narrative or ‘world view’ as the basis of the propagation of an Jacqueline McLaughlin ([email protected]) is that encompasses and makes sense of action potential along the membrane assistant professor of biology at the Pennsyl- vania State University, Lehigh Valley. She is the observations and successful pre- of a neuron, and microtubule depoly- also director of the professional development dictive tools in a field of study.” merization and protein motors at the program CHANCE (https://royercenter.cwc. A theory is not a hunch; it is the kinetochores to move chromosomes psu.edu/CHANCE). scientifically grounded way of explain- during anaphase.
60 JOURNAL of COLLEGE SCIENCE TEACHING These explanations remain as bi- Recently, I had the honor of judg- prove…” When they finished their ological theories and are the concepts ing a regional science fair, the Penn- presentations they smiled with pride that fill biological textbooks. Are you sylvania Junior Academy of Science at having given us, the judges, what wondering if you should purchase a (PJAS). I also had the honor of taking they thought was the most important new edition of your biology textbook? fifteen of my brightest undergradu- entity in science—positive results When one truly realizes that science ate biology majors to this event and that prove something. is in a state of perpetual flux, that having them act as judges. Several For the sake of my devotion to what’s in print today may be outdated of my college students were placed real scientific investigation I asked the tomorrow, this question won’t even together as judges, but most of them presenters if they truly felt they had cross your mind. Again, all of our were placed with judges from all over proven their hypothesis. When they current understanding of scientific our region—professionals working in replied ‘yes’ I proceeded to give my phenomena is theoretical and could be industry, academia, and health care. speech that no amount of experimental revised in a heartbeat if commendable It was a spectacular sight, seeing my evidence or testing can prove a hy- and repeatable evidence falsifies it and students all dressed up and acting pothesis beyond a shadow of a doubt. supports a new theory. like scientists, ready to use the core A hypothesis gains credibility from Colleagues, it is time to bring biological concepts and inquiry-based positive data that support it. If they honor and dignity back to the ‘history scientific methodology I had taught had supplied the scientific world with of scientific investigation’ that has pre- them. They were ready and eager to evidence or new knowledge to support vailed for centuries. We must act and act as role models and mentors, and their hypotheses then, with additional work together as professional educa- I was ready to embrace helping them supporting evidence from others doing tors to correct the misconceptions that and all the middle school presenters research on the same topic, a theory or a theory is a hunch, and that science is practice their scientific vocabulary. an integrated explanation of a number absolute. As Dr. French pointed out, You see, I had judged many science of hypotheses, may emerge. This re- one way is to have a disclaimer in our fairs before this one, and knew what minder doesn’t fall on deaf ears, as my textbooks that would make the under- was awaiting all of us. own students showed me at the end of pinnings of science explicit—that our I, along with three other judges, the day. They rushed to me with glee explanations are tentative and open to presided over eight of some of the to tell me that they’d had to explain challenge, that what’s in our textbooks brightest and motivated middle scientific theory to the middle school just happens to be the best theories school students I had ever interacted students they judged. The lesson for thus far, and that science is a process. with. Their experiments focused on the day was that in science we cannot Another way is this: listen to our stu- topics such as the effects of moisture explain anything with 100% accuracy; dents and non-scientist community and and temperature on fungal growth, our data either support or negate our gently remind them to be careful with the role pH plays on the decom- hypotheses. One is not better than the their words. This step also requires that position of soil, and the inhibitory other since from negative results we we become more cautious with our effects of preservatives on bread can actually learn more. own words. By using the appropriate mold growth. They were all elegantly In our present world, research sci- words when we speak about research prepared experiments that followed entists are fighting to reinforce to the in a public forum, we can correct the the “textbook” scientific method of non-scientific world that the “theory misconceptions that science is a done formulating a question, developing a of global warming” and the “theory of deal, and that a theory is a hunch. hypothesis, designing an experiment, evolution” (to name two hot-topic the- So what are the words that we determining the variables, present- ories) are not mere guesses or hunches, need to keep in mind? The hardest part ing and analyzing results, and then but explanations based on reliable data about understanding scientific theories interpreting the results. The last that should be taken seriously. Ideas or and hypotheses seems to be this: a hy- step, however, was the only one that hunches that are not grounded in scien- pothesis is never proven correct, nor is needed attention. Most students got tific evidence, like intelligent design, a theory ever proven to be true. Words to their conclusion section and stated, should not be associated with the word like prove, correct, and true should be “My hypothesis is correct because I theory. Scientists pride themselves removed from our vocabulary com- have proved that…” or even, “My on being able to present data that can pletely and immediately. hypothesis is correct because my data stand up to the test of time and, if not,
SEPTEMBER 2006 61 A 21st Century
Science Lab... can lead us to new discoveries, like a 10th planet in the Kuiper Belt. I urge all of us to gently remind Wherever you need it ourselves and those we mentor that In your science lab or outdoors— a hypothesis is never proven correct. with or without a computer. And that no amount of experimental testing or evidence can prove anything in science. If a scientist’s results match Unrivaled his/her prediction, then the hypothesis is supported. This, like the disclaimer Capability, in our textbooks, is a start. Unrivaled Reference French, D. 2006. Should we allow Price. disclaimers in textbooks? Maybe the right ones. Journal of College Science Teaching 35 (5): 54–55. 4 Built-in Sensors Morrison, D. 2005. Only a theory? – Temperature (2) Framing the evolution/creation – Voltage – Sound issue. Skeptical Inquirer 29 (6): 37–41. 4 Universal Sensor Ports Supports the full line of ov PASPORT® Sensors, inclu PASCO’s unique MultiMea Sensors™
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62 JOURNAL of COLLEGE SCIENCE TEACHING