Abstract

In recent years the notion of biological specificity has attracted significant philosophical attention. This paper focuses on host specificity, a kind of biological specificity that has not yet been discussed by philosophers, and which concerns the extent to which a species is selective in the range of other species it exploits for feeding and/or reproduction. Host specificity is an important notion in ecology, where it plays a variety of theoretical roles. Here I focus on the role of host specificity in biological control, a field of applied ecology that deals with the suppression of pests through the use of living organisms. Examining host specificity and its role in biological control yields several valuable contributions to our understanding of biological specificity. In particular, I argue that host specificity cannot be fully understood in terms of Woodward’s well-known account of causal specificity. To adequately account for host specificity, we need a notion of causal specificity that takes into consideration the extent to which a variable’s effects are similar to one another – a dimension not captured in Woodward’s account. In addition, the literature on host specificity in biological control highlights certain aspects in which causally specific relationships can be practically valuable that have not yet been addressed in philosophical discussions of specificity. That literature also reveals that in certain contexts specificity can hinder rather than foster effective control, thus leading to a nuanced assessment of the practical value of specific causes.