Scientific evidence

Scientific evidence for a theory consists of observations and measurements which are consistent with predictions made by the theory. When a theory remains consistent with the facts, no matter how hard scientists try to find counter-examples, scientific confidence in the theory is bolstered.

Findings which are contrary to a theory normally cast doubt upon it. The theory must then be discarded, or significantly modified.

Sometimes, however, scientists have refused to examine new evidence which could undermine confidence in an established theory. Possibly the best known case of this involved the discoveries of Ignaz Semmelweis in 19th century Vienna, which led to the germ theory of disease.