 To introduce the third comment on Lewis’s approach, let us compare it with Choi and Gundersen’s approach that rules out finks, reverse-cycle finks, maskers, mimickers, etc., from the stimulus condition. A conspicuous difference between them is that, whilst, on Choi and Gundersen’s approach, all of the problems of finks, reverse-cycle finks, maskers, and mimickers are handled in a uniform manner, this is not the case for Lewis’s approach. Lewis deals with them by invoking diverse elements in RCA: the condition that \(x\) retain an intrinsic property for a sufficient time, the condition that the intrinsic property causally contribute to the occurrence of the manifestation, the condition that maskers be absent from the stimulus condition, the condition that the manifestation of fragility be \(x\)’s breaking through a certain direct and standard process. Other things being equal, this difference will favour Choi and Gundersen’s approach over Lewis’s as explanatory unity is a theoretical virtue. (See Gundersen 2017 and Schlosser 2018 for an ongoing dispute about RCA’s viability.)