The paper exposes the principal procedures of assessing methodological theories. The first one is based on a consensus about the aims of science, the second uses epistemological criteria, and the third checks the adequacy of methodological requirements against the history of science. This third procedure is singled out for a more detailed treatment. It is argued that rational reconstruction constitutes a separate level of historiography and concerns historical explanation. The subject of a rational reconstruction is the methodological explanation of all (...) basic value judgments, whereas all additional factors are not determined by methodological rules. It is further specified in which way rationally reconstructed history should correspond to the actual course of historical events, i. e. to which extent rational reconstruction is free to interpret history according to methodological categories. In the last paragraph the connection between scientific progress and the growth of knowledge is discussed. (shrink)