After reviewing several failed arguments that laws cannot change, I use the laws' special relation to counterfactuals to show how temporary laws would have to differ from eternal but time-dependent laws. Then I argue that temporary laws are impossible and that neither Lewis's nor Armstrong's analyses of law nicely accounts for the laws' immutability. *Received September 2006; revised September 2007. ‡Many thanks to John Roberts and John Carroll for valuable comments on earlier drafts, as well as to several anonymous referees (...) for their good suggestions. †To contact the author, please write to: Department of Philosophy, University of North Carolina, CB #3125, Caldwell Hall, Chapel Hill, NC 27599-3125;. (shrink)

Ellis argues that certain essential properties of objects in the world not only determine the nature of these objects but also how they will behave in any situation. In this paper I will critique Ellis's essentialism from the perspective of the philosophy of chemistry, arguing that our current knowledge of chemistry in fact does not lend itself to essentialist interpretations and that this seriously undercuts Ellis's project. In particular I will criticize two key distinctions Ellis draws between internal vs. external (...) properties and essential vs. accidental properties, showing that at the chemical level such distinctions are insupportable. If essential properties only exist at the level of sub-atomic physics, then Ellis's hopes that essentialism will provide a theoretical basis for a philosophy of chemistry are at best hopes for a very distant future, since the argument that chemical structure and dynamics can be explained at the quantum level derived is purely from analogy to much simpler systems than those chemists actually study. This suggests that we have very little scientific evidence that scientific essentialism is a viable ontology. †To contact the author, please write to: Department of Philosophy, University of Notre Dame, Notre Dame, IN 46556; e-mail: [email protected]. (shrink)

In Lange 2004a, I argued that 'scientific essentialism' [Ellis 2001 cannot account for the characteristic relation between laws and counterfactuals without undergoing considerable ad hoc tinkering. In recent papers, Brian Ellis 2005 and Toby Handfield 2005 have defended essentialism against my charge. Here I argue that Ellis's and Handfield's replies fail. Even in ordinary counterfactual reasoning, the 'closest possible world' where the electron's electric charge is 5% greater may have less overlap with the actual world in its fundamental natural kinds (...) than a 'more distant possible world' where the electron's charge is 5% greater. But more importantly, essentialism's flexibility in being able to accommodate virtually any relation between laws and counterfactuals is a symptom of essentialism's explanatory impotence as far as that relation is concerned. (shrink)