 Kenneth Schaffner explicitly built upon Nagel’s model, with a special focus on extending it to cover cases of correction and replacement. Appealing to the facts of actual scientific theory succession, Schaffner proposed an alternative model of reduction (Schaffner 1993: chapter 9; earlier versions can be found in his 1967, 1974, and 1976) based on the following main idea: If we want our definition to cover the relevant sort of cases of actual scientific developments, we must not focus solely on straightforward reductions; mere replacements and cases of theory-correction should be incorporated as well because (most, or at least a considerable number of) actual theory-successions do not fit into the picture of reductions in the more narrow sense (see, for example, Schaffner 1993: 426, 427f).