 One kind of case which resists reduction is where there is no single relation between the social phenomenon and individual properties, because the relevant macro-level phenomenon can be realised in multiple ways at the micro-level. Examples might include the idea of “fittingness” in evolutionary biology, or of “economic survival” (of capitalist firms) in economics (Wright, Levine, &amp; Sober 1992: 119). In such circumstances, no particular micro-level account can be identified as explaining the macro-level phenomenon, because the latter can be realised in multiple combinations of the former. The provision of a micro-level account might still be desirable—for instance, identifying a possible micro-foundation might improve our confidence in the macro-level explanation—but here it offers no support for a general project of reduction (1992: 122). In short, Wright, Levine, and Sober recognise that facts about social phenomenon might supervene on facts about individuals and their interaction, without it being the case that all social phenomenon can be explained in individualistic terms alone. The question of how many social phenomenon are irreducible to individual level properties looks to be an open empirical matter (List &amp; Spiekermann 2013).