A scientific theory is a well-established explanation of some aspect of the natural world. Theories come from scientific data and multiple experiments. While it is not possible to prove a theory, a single contrary result using the scientific method can disprove it. In other words, a theory is testable and falsifiable.
Examples of Scientific Theories
There are many scientific theory in different disciplines:
- Astronomy: theory of stellar nucleosynthesis, theory of stellar evolution
- Biology: cell theory, theory of evolution, germ theory, dual inheritance theory
- Chemistry: atomic theory, Bronsted Lowry acid-base theory, kinetic molecular theory of gases, Lewis acid-base theory, molecular theory, valence bond theory
- Geology: climate change theory, plate tectonics theory
- Physics: Big Bang theory, perturbation theory, theory of relativity, quantum field theory
Criteria for a Theory
In order for an explanation of the natural world to be a theory, it meets certain criteria:
- A theory is falsifiable. At some point, a theory withstands testing and experimentation using the scientific method.
- A theory is supported by lots of independent evidence.
- A theory explains existing experimental results and predicts outcomes of new experiments at least as well as other theories.
Difference Between a Scientific Theory and Theory
Usually, a scientific theory is just called a theory. However, a theory in science means something different from the way most people use the word. For example, if frogs rain down from the sky, a person might observe the frogs and say, “I have a theory about why that happened.” While that theory might be an explanation, it is not based on multiple observations and experiments. It might not be testable and falsifiable. It’s not a scientific theory (although it could eventually become one).
Value of Disproven Theories
Even though some theories are incorrect, they often retain value.
For example, Arrhenius acid-base theory does not explain the behavior of chemicals lacking hydrogen that behave as acids. The Bronsted Lowry and Lewis theories do a better job of explaining this behavior. Yet, the Arrhenius theory predicts the behavior of most acids and is easier for people to understand.
Another example is the theory of Newtonian mechanics. The theory of relativity is much more inclusive than Newtonian mechanics, which breaks down in certain frames of reference or at speeds close to the speed of light. But, Newtonian mechanics is much simpler to understand and its equations apply to everyday behavior.
Difference Between a Scientific Theory and a Scientific Law
The scientific method leads to the formulation of both scientific theories and laws. Both theories and laws are falsifiable. Both theories and laws help with making predictions about the natural world. However, there is a key difference.
A theory explains why or how something works, while a law describes what happens without explaining it. Often, you see laws written in the form of equations or formulas.
Theories and laws are related, but theories never become laws or vice versa.
Theory vs Hypothesis
A hypothesis is a proposition that is tested via an experiment. A theory results from many, many tested hypotheses.
Theory vs Fact
Theories depend on facts, but the two words mean different things. A fact is an irrefutable piece of evidence or data. Facts never change. A theory, on the other hand, may be modified or disproven.
Difference Between a Theory and a Model
Both theories and models allow a scientist to form a hypothesis and make predictions about future outcomes. However, a theory both describes and explains, while a model only describes. For example, a model of the solar system shows the arrangement of planets and asteroids in a plane around the Sun, but it does not explain how or why they got into their positions.
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- Halvorson, Hans (2012). “What Scientific Theories Could Not Be.” Philosophy of Science. 79 (2): 183–206. doi:10.1086/664745
- McComas, William F. (December 30, 2013). The Language of Science Education: An Expanded Glossary of Key Terms and Concepts in Science Teaching and Learning. Springer Science & Business Media. ISBN 978-94-6209-497-0.
- National Academy of Sciences (US) (1999). Science and Creationism: A View from the National Academy of Sciences (2nd ed.). National Academies Press. doi:10.17226/6024 ISBN 978-0-309-06406-4.
- Suppe, Frederick (1998). “Understanding Scientific Theories: An Assessment of Developments, 1969–1998.” Philosophy of Science. 67: S102–S115. doi:10.1086/392812