 Ideas similar to those of Nagel have been pursued, amongst others, by Robert Causey and Lawrence Sklar (Sklar 1967). Causey’s model of microreductions suggests that reductions are based in cross-theoretic identities and are, in a sense, decompositional (Causey 1972a,b). Kenneth Schaffner explicitly built upon Nagel’s model, extending it especially to cover cases of correction and replacement.