Science Is a Process (4 of 4)

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Theories are central to scientific thinking.
Theories are overarching explanations that make sense of some aspect of nature, are based on evidence, allow scientists to make valid predictions, and have been tested in many ways. Theories are supported, modified, or replaced as new evidence appears. Theories give scientists frameworks within which to work. Major theories of science, such as the cell theory, gravitational theory, evolutionary theory, and particle theory, are all big ideas within which scientists test specific hypotheses.

The scientific definition of “theory” should not be confused with the way the term is commonly used to mean a guess or a hunch. In science, a theory means much more and is far more well-founded. The “Theory of Evolution” is an evidence-based, internally consistent, well-tested explanation of how the history of life proceeded on Earth—not a hunch. Understanding the role of theory in science is essential to scientists and vital to the informed citizen.