On Calcott's permissive and instructive cause distinction

I argue that Calcott (in Biol Philos 32(4):481–505, Calcott 2017) mischaracterizes in an important way the notion of causal specificity proposed by Woodward (in Biol Philos 25(3):287–318, Woodward 2010). This leads him to (1) rely too heavily on one single aspect of Woodward’s analysis on causal specificity; (2) propose an information-theoretic measure he calls ‘precision’ which is partly redundant with, but less general than one of the dimensions in Woodward’s analysis of specificity, without acknowledging Woodward’s analysis; and (3) claim that comparing the specificities of two or more causes under what he calls a competitive analysis of causes, does not permit to capture the distinction between permissive and instructive causes. After having restated Woodward’s analysis of causal specificity, I present an information-theoretic measure (variation of causal information) which, although related to Calcott’s measure, is more general than his and corresponds to the notion of specificity he missed in Woodward's analysis. I then show how this measure can be used, together with mutual causal information (which captures another dimension of specificity in Woodward’s analysis), to distinguish permissive from instructive causes in a competitive analysis of causes.