The No Alternatives Argument

Scientific theories are hard to find, and once scientists have found a theory, H, they often believe that there are not many distinct alternatives to H. But is this belief justified? What should scientists believe about the number of alternatives to H, and how should they change these beliefs in the light ofnewevidence? These aresomeof the questions that we will address in this article. We also ask under which conditions failure to find an alternative to H confirms the theory in question. This kind of reasoning (which we call the ‘no alternatives argument') is frequently used in science and therefore deserves a careful philosophical analysis.