Abstract

A chemical reaction is a causal process in which one set of chemical species is converted into another set of chemical species. Chemists are able to intervene on this process, influencing the product distribution by manipulating a range of variables. This process looks very much like interventionist causation; at a cursory glance, chemical reactions therefore seem well suited for interventionist causal modeling. I test this supposition, using James Woodward’s interventionist theory of causation to model three different ways that chemists are able to manipulate the reaction conditions in order to control the outcome of a reaction. These consist in manipulations to the reaction kinetics, thermodynamics, and whether the kinetics or thermodynamics predominates. It is possible to construct interventionist causal models of these kinds of manipulation, and therefore to account for them using Woodward’s theory. However, I show that there is an alternate, more illuminating way of thinking about the third kind of reaction control, according to which chemists are actually manipulating which causal system is instantiated. Our ability to manipulate which system is instantiated is an important part of our ability to control the world, as is therefore especially relevant to interventionism. Thus, considering examples from organic chemistry leads to the identification of an important extension to Woodward’s theory.