Peacocke, Arthur. “Chance and Law in Irreversible Thermodynamics, Theoretical Biology, and Theology.”

Arthur Peacocke’s topic in this reprint is the general relationship between chance and law in thermodynamics and biology, and its implications for belief in God as creator.

Chance may be the means for actualizing the possibilities of the world, but it need not be seen as a metaphysical principle opposed to order or undercutting the meaning of life. Chance actually has two quite distinct meanings: it can refer simply to our ignorance of the processes which underlie an event, or it can refer to unpredictable intersections of previously unrelated causal chains. Recently, the interplay between chance and law has come to be seen as crucial to the origin and development of life, particularly through the work of Jacques Monod in molecular biology and Ilya Prigogine in irreversible thermodynamics and theoretical biology. As Monod emphasizes, evolution depends on chance, in the sense of two independent causal chains, operating in living organisms: one is at the genetic level, including changes in the nucleotide bases of DNA; the other is at the level of the organism, including interactions between the organism expressing these changes and its environment. Chance also arises here in the sense that we cannot now (nor may we ever be able to) specify the mechanisms underlying genetic mutations.

Though agreeing with him this far, Peacocke challenges both Monod’s generalization of the role of chance from the context of evolution to include all of human culture, and his subsequent conclusion to the meaningless of life. Instead, Peacocke sees chance as the means by which all possibilities for the organization of matter are explored in nature.

Peacocke then turns to irreversible thermodynamics and theoretical biology. Thermodynamics is “the science of the possible” which prescribes how nature can behave. Classical thermodynamics, with its focus on systems in equilibrium, centers on the second law of increasing entropy in closed systems. Through the statistical thermodynamics of Boltzmann this came to be seen as increasing disorder or randomness in closed systems. How, then, do living organism maintain themselves in a high state of organization and a low state of entropy, given the second law? The answer, as Peacocke points out, is that living systems are open to their environment. By exchanging energy and matter with it they can decrease in entropy as long as there is an increase in the net environmental entropy.

But does thermodynamics help us to understand how more complex organisms come to be in the first place? The answer comes only with the extension of classical thermodynamics, first to linear, and then to non-linear, irreversible processes involved in what are called dissipative structures. According to Prigogine, if fluctuations in these non-linear, non-equilibrium structures are amplified, they can change the structures and result in new, more ordered states. The answer also includes the key role played by multiple and relatively stable strata in the hierarchy of biological complexity. These intermediate strata enhance the rate of evolution of more complex organisms from very simple ones, in effect directing evolution towards increased complexity. In essence, the evolution of chemical, pre-biological, and biological complexity is seen as probable, perhaps even inevitable, although the particular path taken in nature is unpredictable. Still, detailed kinetic and dynamic requirements, as well as thermodynamic ones, must be met for evolution to occur.

Peacocke then turns briefly to theological reflections. God is creator of the world through a timeless relation to it in two ways. God is totally other than the world, its transcendent ground of being. God is also immanent in the world, continuously creating all that is through its inbuilt evolutionary processes. These processes, revealed by the natural sciences, are in fact God’s action in the world, and eventually include the evolution of humanity. Thus, all-that-is is in God, but God is “more” than nature and humanity. The complex interplay of law and chance is itself “written into creation by the creator’s intention and purpose,” to emerge in time by the explorations of nature. Here Peacocke suggests the metaphor of God as a musical composer and nature as God’s composition, perhaps like a rich fugue.

But does this metaphor carry deistic overtones, as H. Montefiore claims? Not according to D. J. Bartholomew, who sees chance as conducive to the production of a world in which freedom can operate purposefully. Still, the best response to the charge of deism, as Peacocke emphasizes, is to see God’s action as immanent within natural processes. Moreover, as Rustum Roy points out, the interplay of chance and law in nature means that we should accept a similar interplay as characteristic of God’s creativity in human life and society, and we should be critical of belief in a God who “intervenes in the natural nexus for the good or ill of individuals and societies.” Peacocke concludes that just as it takes a stream to have eddies, it is the existence of the universe, flowing as it does towards overall increasing entropy, that is required if there are to be eddies of biological life.

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