What distinguishes a scientific theory from a non-scientific theory is that a scientific theory must be refutable in principle; a set of circumstances must potentially exist such that if observed it would logically prove the theory wrong.
Here is a simplified version of the logic of the scientific method: we begin the encounter with nature by making observations and then through some creative process a hypothesis is generated about how some process of nature works. On the basis of this hypothesis, an experiment is logically deduced that will result in a set of particular observations that should occur, under particular conditions, if the hypothesis true. If those particular observations do not occur, then we are faced with several possibilities: our hypothesis needs to be revised, the experiment was carried out incorrectly, or the analysis of the results from that experiment was in error.
The actual process often involves a great deal of insight and creativity. Keep in mind, though, that this interpretive process may have biased the outcome or conclusions. This point will be addressed later. For now, simply note that without a disconfirmation being possible in principle, a belief is not acceptable as even a potential scientific hypothesis. There must be a possible concrete test.
This refutability and the testable predictions of a "good" or useful scientific theory should extend even further. A scientific theory must make testable or refutable predictions of what should happen or be seen under a given set of new, independent, observing or analysis circumstances from the particular problem or observation the theory was originally designed to explain. For example, the seeming contradiction between Uranus' predicted position from Newton's celestial mechanics was explained by the presence of a previously unknown planet, Neptune, whose position was predicted from Newton's celestial mechanics. Astronomers found Neptune just where the theory said it should be. Newton's theory was not originally developed to explain Uranus' or Neptune's motions and it was tested via telescopic observations.
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last updated: June 1, 2007