  The episode of the fifth force is the case of a refutation of an hypothesis, but only after a disagreement between experimental results was resolved. The “Fifth Force” was a proposed modification of Newton’s Law of Universal Gravitation. The initial experiments gave conflicting results: one supported the existence of the Fifth Force whereas the other argued against it. After numerous repetitions of the experiment, the discord was resolved and a consensus reached that the Fifth Force did not exist. (For details of this episode see  Appendix 4.)