 A related concern is voiced by Horwich (1987: 172) who asks “why we should have evolved such a baroque notion of counterfactual dependence”, namely that captured by Lewis’ (1979) System of Weights. The concern has two components: why would humans find it useful, and why would human psychology ground counterfactuals in this concept of similarity rather than our ready-at-hand intuitive concept of overall similarity? These questions are given more weight given the centrality of counterfactuals to human rationality and scientific explanation outlined in §1. Psychological theories of counterfactual reasoning and representation have found tools other than similarity more fruitful (§1.2). Similarly, work on scientific explanation has not assigned any central role for similarity (1.3), and as Hájek (2014: 250) puts it: 