OCKHAMS-RAZOR AND CHEMISTRY

We begin by tracing the personal and scholarly history of William of O ckham, the man whose name Ockham's Razor bears. His various formulatio ns of the principle of parsimony are presented. We then define a react ion mechanism and tell a personal story of how Ockham's Razor entered the study of one such mechanism. A small history of methodologies rela ted to Ockham's Razor, least action and least motion, follows. This is all done in the context of the chemical (and scientific) community's almost unthinking acceptance of the principle as heuristically valuabl e. Which is not matched, to put it mildly, by current philosophical at titudes toward Ockham's Razor. What ensues is a dialogue, pro and con. We first present a context for questioning, within chemistry, the fun damental assumption that underlies Ockham's Razor, namely that the wor ld is simple. Then we argue that in more than one pragmatic way the Ra zor proves useful; without at all assuming a simple world. Ockham's Ra zor is an instruction in an operating manual, not a world view. Contin uing the argument, we look at the multiplicity and continuity of conce rted reaction mechanisms, and at principal component and Bayesian anal ysis (two ways in which Ockham's Razor is embedded into modern statist ics). The dangers to the chemical imagination from a rigid adherence t o an Ockham's Razor perspective, and the benefits of the use of this v enerable and practical principle are given, we hope, their due.