BETWEEN THE FUNDAMENTAL AND THE PHENOMENOLOGICAL - THE CHALLENGE OF SEMIEMPIRICAL METHODS

Philosophers disagree how abstract, theoretical principles can be appl ied to instances. This paper generates a puzzle for law theorists, cau sal theorists and inductivists alike. Intractability can force scienti sts to use a ''semi-empirical'' method, in which some of an equation's theoretically-determinable parameters are replaced with values taken directly from the data. This is not a purely deductive or inductive pr ocess, nor does it involve causes and capacities in any simple way (Hu mphreys 1995). I argue the predictive successes of such methods requir e us to reanalyze our views about the nature of prediction, the status of models, and the goal(s) of science. When laws and experimental evi dence are neither individually nor jointly sufficient for prediction, models become the locus of understanding. I analyze an historically im portant debate about the use of semi-empirical methods to construct po tential energy surfaces.