What is the Scientific Theory? - Definition, Characteristics & Example

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  • 0:03 What are Scientific Theories?
  • 1:21 Fact or Theory?
  • 1:45 Characteristics of a Theory
  • 3:44 Examples of a Theory
  • 4:42 Lesson Summary
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Lesson Transcript
Instructor: Nadine James

Nadine has taught nursing for 12 years and has a PhD in Nursing research

In this lesson, you'll learn the definition and characteristics of a scientific theory and understand how theories are formulated. You'll see examples of scientific theories, and after the lesson you can test your knowledge with a brief quiz.

What Are Scientific Theories?

Have you ever wondered how scientists develop theories? What are scientific theories, anyway? Is the definition of a theory different in the scientific community?

Outside of science, the definition of a theory is a thought that may or may not be true. In the science community, a scientific theory is defined as a hypothesis or a group of hypotheses about some phenomena that have been supported through research using the scientific method.

A hypothesis is basically an educated guess. For instance, a scientist observes something happening repeatedly over time, and a question or a group of questions begin to be formed. One question could be: 'Why am I observing this happening?' Another question might be: 'Could this be occurring every time, or is this just a coincidence?'

To answer these questions, a scientist, or a group of scientists, do an experiment to test the hypothesis. This is described as scientific research. Often, the research studies that are conducted with hypothesis testing happen over a long period of time. After many repeated research studies, a scientist would move to call the hypothesis a theory.

The Scientific Method
The Scientific Method

Fact or Theory?

So, we have scientific facts and we have scientific theories. What's the difference? Scientific facts are measured and/or observed. They never change and are unmistakable evidence. Scientific theories are the scientist's interpretation of the facts. Scientists may have differing opinions regarding the best interpretation of the facts. Theories can change and be rejected.

Characteristics of a Scientific Theory

Although there are many characteristics of scientific theories, there are five basic characteristics that can help you understand how they work. A scientific theory should be:

  1. Testable: Theories can be supported through a series of scientific research projects or experiments. Sometimes a theory is proven to be wrong through evidence: this is called rejecting a theory. However, a theory can never be proven to be absolutely true because it is an interpretation. There is always the possibility that a different interpretation will someday be found to be more correct.
  2. Replicable: In other words, theories must also be able to be repeated by others. This means that enough information and data must be available in the theory so that others can test the theory and get similar results.
  3. Stable: Another characteristic of theories is that they must be stable. This means that when others test the theory, they get the same results - so a theory is valid as long as there is no evidence to dispute it.
  4. Simple: A theory should be simple. When we say a scientific theory must be simple, we don't mean that the concept must be basic. We mean that only useful, relevant information should be presented in the theory.
  5. Consistent: A theory should agree with other theories, meaning that no principles in one theory should contradict another already accepted theory. However, some differences may be evident because the new theory may provide additional evidence.

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