 Consider the example of pain reducing to C-fiber stimulation. Under one interpretation, the expressions ‘pain’ and ‘C-fiber stimulation’ pick out abstract objects, namely natural kinds, properties or types. On this reading of ‘pain reduces to C-fiber stimulation’, the primary relata of reduction should be conceived of as properties or types. This view has played an important role in the philosophy of mind, underlying classical versions of type-identity theory and being the main target of anti-reductionist’s counter-attacks (Putnam 1967; Fodor 1974, 1997).