Scientific study designed to increase our knowledge of natural phenomena can follow at least three different intellectual methods. These can be called the method of the ruling theory, the method of the working hypothesis, and the method of multiple working hypotheses. The first two are the most popular but they can, and often do, lead to ineffective research that overlooks relevant data. Instead, the method of multiple working hypotheses offers a more effective way of organising one's research.
The method of multiple working hypotheses involves the development, prior to our research, of several hypotheses that might explain the phenomenon we want to study. Many of these hypotheses will be contradictory, so that some, if not all, will prove to be false. However, the development of multiple hypotheses prior to the research avoids the trap of the ruling hypothesis and thus makes it more likely that research will lead to meaningful results. One can open-mindedly envision all the possible explanations of the phenomenon to be studied, including the possibility that none of explanations are correct ("none of the above") and the possibility that some new explanation may emerge.
The method of multiple working hypotheses has several other beneficial effects on one's research. Careful study often shows that a phenomenon is the result of several causes, not just one, and the method of multiple working hypotheses obviously makes it more likely that we will see the interaction of the several causes. The method also promotes much greater thoroughness than research directed toward one hypothesis, leading to lines of inquiry that one might otherwise overlook, and thus to evidence and insights that single-minded research might never have encountered. Thirdly, the method makes one much more likely to see the imperfections in one's knowledge and thus to avoid the pitfall of accepting weak or flawed evidence for one hypothesis when another provides a more elegant solution.
Chamberlin, T.C., 1890, The method of multiple working hypotheses: Science (old series) v. 15, p. 92-96; reprinted 1965, v. 148, p. 754-759.