Kohei Morita

Intertheoretical relationships have been traditionally investigated through the notions of reduction and emergence. Recently, the focus has shifted towards the relationship between models for elaborating intertheoretical relationships in physics. This article demonstrates that three, rather than two, types of models are essential for elucidating some intertheoretical relationships. Beyond the conventional higher- and lower-level models, an intermediate-level model is crucial for establishing connections between the theories. This framework is not only applicable to some practical cases but also effectively captures the characteristics of two significant intertheoretical relationships: between classical and quantum mechanics, and between thermodynamics and statistical mechanics. By applying this framework to these cases, this study highlights both the similarity and the difference in these intertheoretical relationships.

This paper aims to distinguish two main types of coarse graining, and reveal the relationship between the notions of coarse graining and emergence. In physics, some forms of coarse graining seem to be indispensable to show a physical property, and the other merely changes our descriptions of the system. To clarify the notion of coarse graining, this article investigates the cases of the renormalization group method and irreversibility, both of which have been important topics in philosophy of science, and the case of the rigid body in classical mechanics, which is an elementary case including coarse graining. The case studies reveal the distinction between substantial and mere coarse-graining. This distinction clarifies the relationships between the notions of coarse graining and emergence and further provides some implications for the issues about emergence.