Fitting Things Together. Coherence and the Demands of Structural Rationality, by Alex Worsnip

Abstract

Two views that have dominated the recent literature on rationality are the coherence-based and the reasons-based conceptions of rationality. According to the first of these views, rationality is a matter of establishing internal coherence between one’s mental states (for example, Scanlon 2007; Broome 2013). On this conception of rationality, it is an open question whether we ought or have any reason to be rational, and some have argued that this question must receive a negative answer (Kolodny 2005). According to the second view, rationality is most fundamentally a matter of responding to reasons (for example, Kiesewetter 2017; Lord 2018). Insofar as incoherence is irrational, this is to be explained in terms of a failure to respond to available reasons, and consequently the normative significance of rationality cannot sensibly be questioned. In Fitting Things Together, Alex Worsnip seeks to establish an alternative to both of these views, which he dubs ‘dualism about rationality’. According to this third view, there are both structural requirements of rationality, which demand coherence among our attitudes, and substantive requirements of rationality, which demand responsiveness to reasons, and these requirements are irre-­ducible to each other. Dualism agrees with the reasons-based view that there is an important dimension of rationality, the normative significance of which cannot sensibly be questioned; but it rejects the thesis that the irrationality of incoherence can be explained in terms of this substantive dimension. Dualism thus agrees with the coherence-based view that there is an important dimension of rationality, the normative significance of which can sensibly be questioned, but denies that this structural dimension exhausts what rationality is about.