Proceedings of the XXII World Congress of Philosophy

Volume 42, 2008

Philosophy of Mind

JeeLoo Liu
Pages 149-160

From Realizer Functionalism to Nonreductive Physicalism

It has been noted in recent literature (e.g., Ross & Spurrett 2004, Kim 2006, McLaughlin 2006 and Cohen 2005) that functionalism can be separated into two varieties: one that emphasizes the role state, the other that emphasizes the realizer state. The former is called “role functionalism” while the latter has been called “realizer functionalism” (Ross & Spurrett 2004, Kim 2006, Cohen 2005) or “filler functionalism” (McLaughlin 2006). The separation between role functionalism and realizer functionalism mars the distinction traditionally made between functionalism and the identity theory, because realizer functionalism can be seen as the synthesis of functionalism and the identity theory. In this paper, I begin with an analysis of the distinction between role and realizer functionalism. I shall further develop realizer functionalism as a viable, or arguably the best, explanatory model for the mind-brain relation. Finally, I will argue that under realizer functionalism, we can give an account of how mind is placed in the material world without at the same time giving up on the autonomy of psychology. The autonomy of psychology is tantamount to the thesis that mental properties are not type-identical with, nor type-reducible to, physical properties of the brain. In the philosophical debate on reductive and nonreductive physicalism, reductivism seems to be gaining the upper hand these days. In the final section of this paper, I shall sketch my defense of nonreductive physicalism. I believe that the current enthusiasm for reductionism is misguided, and I shall show that under realizer functionalism, reductionism in the sense of reductive explanation, i.e., providing explanation of the psychological in terms of the underlying physical properties, is not a feasible project.