Theory

A theory is an explanation for an observed phenomenon that is consistent with all known evidence and has withstood repeated tests designed to disprove it. A theory originates from a valid hypothesis.

A theory should have predictive capabilities: that is, it should identify things that should happen and should not happen in situations to which it applies. It is possible for a given phenomenon to have multiple theories to explain it, so long as all of the theories are consistent with the known evidence.