All suggested notions of reduction of two scientific theories are critically reviewed and analyzed. In particular those applied to the case of the alleged reduction of Chemistry to Quantum mechanics are examined. Since it is recognized that the weakness of this field of research is the lack of a definition of a scientific theory, it is suggested that a scientific theory is characterized by two choices regarding two dichotomies, that is, the kind of mathematics and the kind of logic. According (...) to this view a reduction is only possible between two theories in which the same choices are shared. As a consequence, only one case of reduction in the history of physics is recognized: physical optics to electromagnetism, a case that is commonly accepted. The other cases of claimed reductions are recognized as impossible, owing to the different choices of the two theories at issue and hence the radical variations in meaning of their shared basic notions. In particular, the claimed reduction of Chemistry to Quantum mechanics is disproved in detail. (shrink)

We conduct a case study analysis of a proposal for the emergence of time based upon the approximate derivation of three grades of temporal structure within an explicit quantum cosmological model which obeys a Wheeler-DeWitt type equation without an extrinsic time parameter. Our main focus will be issues regarding the consistency of the approximations and derivations in question. Our conclusion is that the model provides a self-consistent account of the emergence of chronordinal, chronometric and chronodirected structure. Residual concerns relate to (...) explanatory rather than consistency considerations. (shrink)