Holism, underdetermination, and the dynamics of empirical theories

The goal of this article is to show that the structuralist approach provides a powerful framework for the analysis of certain holistic phenomena in empirical theories. We focus on two aspects of holism. The first refers to the involvement of comprehensive complexes of hypotheses in the theoretical treatment of systems regarded in isolation. By contrast, the second refers to the correlation between the theoretical descriptions of different systems. It is demonstrated how these two aspects can be analysed by making use of the structuralist notion of theory-nets, and how they are reflected by a refined version of the Ramsey sentence. Furthermore, it is argued that there exists a tight correlation between the occurrence of these two holistic phenomena, a specific form of underdetermination of terms which occur in the fundamental principles of an empirical theory, and the shaping of the theory's protective belt. After having dealt with these questions in abstracto, the relevance of these considerations for a better understanding of the dynamics of empirical theories is demonstrated in a concrete case study. It refers to the role holistic phenomena played in the investigation of the anomalous advance of Mercury's perihelion and in the various attempts to eliminate this anomaly.