The word ‘theory’ has several meanings and can be confusing. Its meaning in the scientific context can differ from that in the context of everyday communication.
According to dictionary.com, these are the meanings of ‘theory’:
- a coherent group of tested general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena: Einstein’s theory of relativity.
- a proposed explanation whose status is still conjectural and subject to experimentation, in contrast to well-established propositions that are regarded as reporting matters of actual fact.
- Mathematics. a body of principles, theorems, or the like, belonging to one subject: number theory.
- the branch of a science or art that deals with its principles or methods, as distinguished from its practice: music theory.
- a particular conception or view of something to be done or of the method of doing it; a system of rules or principles: conflicting theories of how children best learn to read.
- contemplation or speculation: the theory that there is life on other planets.
In the scientific context, ‘theory’ means 1, 3, or 4. On the other hand, in everyday communications, ‘theory’ often means 2.
Some flat-Earthers would assume that because something is called a ‘theory,’ then it is still unproven. For example, when they find the phrase “theory of relativity” in scientific books, they would incorrectly conclude that the theory of relativity is still unproven.
In the scientific context, an unproven supposition is referred to as a ‘hypothesis’ instead, not a ‘theory.’