| Aristotle and Galileo created explanations of the fact of gravity. These are now obsolete explanations. | Lamarckism, Transmutationism and Orthogenesis were created as explanations of the fact of evolution. These are now discredited explanations. |
| Newton’s explanation of gravity is approximately correct but required refinement. | Darwin’s explanation of evolution is approximately correct, but required refinement. |
| Einstein’s explanation is a refinement of Newton’s explanation of gravity. Einstein’s explanation is currently the most accepted explanation of the fact of gravity. | The modern evolutionary synthesis is a refinement of Darwin’s explanation of evolution, which did not include genes in its explanation. This modern synthesis is currently the most accepted explanation of the fact of evolution. |
| Einstein’s explanation of the fact of gravity is called The General theory of relativity. | The explanation of the fact of evolution provided by the modern synthesis is the latest and most widely accepted Theory of Evolution. |
| Gravity is a fact and a theory. | Evolution is a fact and a theory. |
11.23.5 Evolution as theory and fact in the literature
The confusion between “fact” and “theory” and the use of the word “evolution” is largely due to some authors using evolution to refer to the changes that occur within species over generations and common descent, while others use the term more generally to include the mechanisms driving the change. However, among biologists at least, there seems to be consensus that evolution is a fact.
11.23.6 Evolution as fact and theory
Commonly “fact” is used to refer to the observable changes in organisms’ traits over generations while the word “theory” is reserved for the mechanisms that cause these changes.
11.23.7 Evolution as fact not theory
Other commentators, focusing on the changes in species over generations and in some cases common ancestry have stressed that evolution is a fact to emphasize the weight of supporting evidence while denying it is helpful to use the term “theory”.
11.23.8 Predictive power
A central tenet in science is that a scientific theory is supposed to have predictive power, and verification of predictions are seen as an important and necessary support for the theory. The theory of evolution did provide such predictions.
11.23.9 Related concepts and terminology
- Speculative or conjectural explanations are called hypotheses. Well-tested explanations are called theories.
- “Fact” does not mean “absolute certainty”.
- “Proof” of a theory does not exist in natural sciences. Proof only exists in formal sciences, such as mathematics. Experimental observation of the predictions made by a hypothesis or theory is called validation.
A scientific law is a concept related to a scientific theory. Very well-established “theories” that rely on a simple principle are often called scientific “laws”. For example, it is common to encounter reference to “the law of gravity”, “the law of natural selection”, or the “laws of evolution.”