Abstract

In its reconstruction of scientific practice, philosophy of science has traditionally placed scientific theories in a central role, and has reduced the problem of mediating between theories and the world to formal considerations. Many applications of scientific theories, however, involve complex mathematical models whose constitutive equations are analytically unsolvable. The study of these applications often consists in developing representations of the underlying physics on a computer, and using the techniques of computer simulation in order to learn about the behavior of these systems. In many instances, these computer simulations are not simple number-crunching techniques. They involve a complex chain of inferences that serve to transform theoretical structures into specific concrete knowledge of physical systems. At the heart of this chain of inferences is the process of building what I call a hierarchy of models. This hierarchy includes a mechanical model, a dynamical model, ad hoc models , a computational model, and finally, a model of the phenomena. ;I argue that this process of transformation is also a process of knowledge creation, and that it has its own epistemology. It is an epistemology that has been ignored by most philosophy of science, which has traditionally concerned itself with the justification of theories, not with their application. I also argue that the complex and motley nature of this epistemology suggests that the end results of simulations often do not bear a simple, straightforward relation to the theories from which they derive. Accordingly, I urge philosophers of science to examine more carefully the process of 'theory articulation.' Theory articulation is a relatively neglected aspect of scientific practice, but it plays a role that is often as crucial, as complex, and as creative as experiment. Finally, I examine in detail the last model in the hierarchy, the model of the phenomena. I argue that these models provide understanding of the systems they model. The character of the understanding they provide, however, is not well accounted for in the philosophical literature on scientific explanation