"How to Keep the Non-Reductive in Nonreductive Physicalism?" by Nancey Murphy: An Appreciative Response

Abstract

"How to Keep the Non-Reductive in Nonreductive Physicalism?" by Nancey Murphy:An Appreciative Response Robert John Russell It is a rare privilege to respond to my colleague and friend of nearly four decades, Nancey Murphy. It is especially wonderful given the nature of this paper, with its inclusion of such diverse areas as biblical and theological anthropology, atomism versus dynamical systems, and a response to the problem of reductionism through an appeal to emergence and downward causality in complex dynamical systems. In this response I will first summarize the second part of Nancey's paper and then raise three questions about it. In the second part of her paper, Murphy begins with the new atomism in classical physics and with it the "inevitability" of causal reductionism. Under the shadow of Thomas Hobbes's reductionist theory of human nature and society the "defeat" of causal reductionism became crucial. A vital step was taken through the articulation of downward causation by Robert Van Gulick. While a system is composed of its parts, the causal powers of a system include both those of its parts and their organization. In the latter case, the system "at least partially determines what contributions are made by its parts."1 An additional step in the defeat of causal reductionism was achieved through the idea of emergence in nature. Murphy cites Terrence Deacon as "providing the best account so far of emergence" and spelled out in terms of three orders of emergence. [End Page 465] Systems with first-order emergence display properties such as the viscosity of liquids, but these properties do not endure. Instead they are dampened out in time, and the reductionist claim is left unthreatened. But in second-order emergence such properties are amplified and have system-wide and long-lasting effects. Finally, third-order emergence arises in biological systems in which second-order systems are selected and constrained by the environment. This complex form of emergence has characteristics which can be called "memory" and give the system a "history." Now she asks a pivotal question: "Do these more sophisticated accounts of emergence and downward causation solve the problem of the reduction of human capacities to biology?" While previously she thought they might, she now raises a point which I find very exciting: How is it not the case that humans are, in a sense, trapped by a combination of downward causation from their environments and the biological factors that do (still) contribute to our behavior? Where is there room for human agency? This is the point at which we must turn to the resources of complex systems theory.2 Here she turns to the work of philosopher of science Alicia Juarrero and her 1999 book, Dynamics in Action. Murphy paraphrases Juarrero in calling for a "shift in ontological emphasis" from "things, with their intrinsic properties, to processes and their relational properties." This shift is warranted by the fact that biological systems are "decoupled" from their atomic components; "if the functional system works, it does not matter what its components are made of."3 Such systems have what philosophers call "internal relations" while elements such as atoms have only "external relations." Hence complex dynamic systems enhance our understanding of causation: Along with routine, efficient causation we now find that constraints are placed on the system by the internal relations between its components and by its relations to the environment which serves as its context. Juarrero also distinguishes between "context-free" and "context-sensitive" constraints. So successive throws of a pair of dice are independent of the results of past throws, but as a card game proceeds, the probability of an "ace" changes by the results of previous draws. This leads Murphy [End Page 466] to recommend that we speak of whole–part "constraints" instead of "downward causation." Here the whole does not exert efficient causality on its parts; instead the whole changes the probabilities of the behavior of its parts. This in turn leads Murphy to set aside the traditional sharp distinction between determinism and indeterminism and adopt the idea of "propensity," a term created by Karl Popper to mean "an irregular or non-necessitating causal disposition of an object or system to produce...