Oliver Lean (University of Calgary)
Recent work in the philosophy of biology has focused on "causal specificity" as a means of comparing the causal importance of genes versus other causal factors in development. In this paper, I aim to bring philosophical attention to a quite different sense of specificity - one that is almost certainly far more important to the study of biological processes at molecular scales. "Binding specificity", as I will call it, refers to the selectivity with which a biomolecule binds to a given target to the exclusion of others. I first outline the role this concept plays in the field of drug design, which explicitly aims to develop drug treatments that are highly specific in this sense, and which does so for clearly-defined purposes. I then apply the lessons learned to interpret binding specificity as a causal concept within the interventionist framework. More specifically, I interpret binding specificiy as a rationale for causal selection - the practice of picking out one or a subset of causes of an effect as "the" cause, or as being especially relevant. Since drug design explicitly selects between candidate drugs based on their specificity, this offers a clear and tractable case study for understanding causal selection. I find that, as well as serving directly practical goals such as the treatment of illness with a minimum of side-effects, molecules with high specificity are also valuable epistemic tools for understanding the causal structure of molecular processes.
