 Shapiro and Polger’s final explicit criterion captures the “differently the same” intuition in terms of quantitative differences. The relevant variation between entities A and B in realizing science S2 “must be greater than” the individual differences between A and B recognized by the realized science S1 (2012: 282, criterion iv). The variation recognized by the realizing science must not merely map onto individual differences between A and B recognized by the realized science. The demands in actually establishing multiple realization are thus quite strict. Not any old variation will do. According to Shapiro and Polger, these strict demands show both that multiple realization in the sense required to fund the standard argument is “a relatively rare phenomenon”—despite the vast variability everywhere in the world—and that a “relatively modest” mind-brain identity theory has little to worry from it (2012: 284).