Toward a general modular systems theory and its application to interfirm product modularity

Many systems migrate toward increasing or decreasing modularity, yet no explicit causal models exist to explain this process. In this article I build a general theory of modular systems, drawing on systems research from many disciplines, and then use this general theory to derive a model of interfirm product modularity, Including testable research propositions. The product model provides a valuable tool for predicting technological trajectories, and it demonstrates how the general theory can be applied to specific systems.