Changes

|Prehistory=In the early twentieth century, many [[Rudolf Carnap|logical positivists]] supported a confirmationist view of theory assessment, in which theories are assessed on the basis of the balance of confirming and disconfirming evidence. In 1945, [[Carl Hempel]], a logical empiricist and confirmationist, argued that , on such grounds, an agent might take one of three stances towards a theory, ''accepting'' it, ''rejecting'' it, or ''withholding judgment'', based on confirming or disconfirming evidence. [[CiteRef::Losee (2001)|p. 167-168]][[CiteRef::Hempel (1945)]]

In his ''Logic of Scientific Discovery'' (1959), [[CiteRef::Popper (1959)]] [[Karl Popper]] argued for a falsificationist view scientific methodology, but a relatively similar set of sciencepossible stances towards theories. Scientific ideas gained ''acceptance'' when they had survived strong tests in which their unexpected novel predictions were verified, and where ''rejected'' when they failed to survive such tests. [[CiteRef::Thornton (2015)]][[CiteRef::Godfrey-Smith (2003)|p. 57-74]]

In [[Imre Lakatos]]'s theory of scientific change individual theories were encompassed in larger assemblages called research programs. A research program consists of a family of scientific theories containing 'hard core' assumptions, which are stubbornly defended, surrounded by a protective belt of associated auxiliary assumptions, which may be modified if needed to protect the hard core. Lakatos identified two epistemic stances with respect to that epistemic agents might take toward research programs. They were could be deemed either ''progressive'' or ''degenerating''. A research program was ''progressive'' if its theories successfully predicted hitherto unexpected facts.It was degenerating if it failed to make such successful bold predictions, and if its theories were fabricated in order intentionally fashioned so as to accommodate already known facts. [[CiteRef::Lakatos (1978)]]

[[Larry Laudan]]'s reticulated model of scientific change involved scientific theories, scientific methods, and scientific values, all interdependent. Methods could change along with theories, and thus epistemic agents could take stances with respect to them both. For Laudan distinguished between the , a theory would be regarded as ''pursuitaccepted'' and by an agent if that agent accepted its truth, or ''acceptancerejected'' if deemed to be false. He also proposed a new stance, that of theories''pursuit''. To accept pursue a theory, for Laudan, is to believe in its truth, and to pursue it is to work with it or explore it without committing to a belief that it is true. A theory may also be ''rejected'' as false. [[CiteRef::Godfrey-Smith (2003)]][[CiteRef::Laudan (1997)|pp. 108-114]]