  Nonreductive physicalism has been challenged for its alleged failure to “pay its physicalist dues” in reductive coin. It is faulted for supposedly not giving an adequate account of how conscious properties are or could be realized by underlying neural, physical or functional structures or processes (Kim 1987, 1998). Indeed it has been charged with incoherence because of its attempt to combine a claim of physical realization with the denial of the ability to spell out that relation in a strict and a priori intelligible way (Jackson 2004).