  This sort of psychophysical property identity would seem to be blocked by the multiple realizability argument sketched earlier. But that argument, in spite of its wide appeal, has come under attack from several directions (see  multiple realizability,  §2). For example, some (Kim 1992; Lewis 1994; Jackson 1995; Heil 2003) take the argument to show, not that mental properties are distinct from their physical realizers, but that what we thought was one kind of mental property is actually many. Pains realized by different physical properties, in spite of having the same name (“pain”), are different, though similar, mental properties. There is no such property as pain simpliciter, only pain-for-this-physical-structure and pain-for-that-physical structure. Once such “structure-specific” identities are allowed, we can say that M (now just, say, pain-for-human beings) is identical with P, M’s “realizer” in human beings (replies include Fodor 1997; Block 1997; Marras 2003; Moore and Campbell 2010).