 The usual justification for grouping distinct realizers under a single functional kind is that such a classification reveals interesting similarities, of the sort we expect to be captured by laws or generalizations of some higher level science. But according to Shapiro, when the realizing kinds differ significantly in their causally relevant properties for the function at issue, any shared laws or generalizations are “numbingly dull” (2000: 649), e.g., all realizers of mouse traps can be used to catch mice, or both camera eyes and compound eyes have the function of enabling the organism to see. Shapiro remarks: 