Introduction and Summary

any Christians are suspicious of the role played by "chance" in evolution. Their suspicions are exacerbated whenever apologists for evolution treat "chance" like some metaphysical entity antithetical to God. This apparent conflict between Chance and God is illusory and unnecessary. The role played by chance in biological evolution --- microevolution or macroevolution --- is no different than the role played by chance in any other scientific theory (e.g. quantum mechanics, statistical mechanics, thermodynamics, meteorology, pathology).

The use of the term "chance" in any scientific theory is not, strictly, a statement about causation (or lack of causation); rather, it is a statement about our lack of knowledge about causation. Theism has always maintained that God can and does determine the outcome of "random" events. Therefore, "random" events in nature are in no way an obstacle to God's providential action; quite the opposite, they are one way in which God could exert providential care.

What do scientists mean by "chance"?

When physicists use the term "chance" in a scientific theory, they mean simply this: The final state of a system cannot be completely specified in terms of its initial conditions, either in principle (e.g. the results of a "quantum measurement"), or in practice. In quantum mechanics, the element of chance is formally built into the theory; the outcomes of quantum measurements can only be specified probabilistically. In classical mechanics, the final state of "chaotic" systems depend so sensitively upon the initial conditions that, in practice, it is impossible to specify all the variables precisely enough to predict the final state. In these systems, based upon experience and certain general considerations, ensembles of final states can be assigned certain probabilities of occurring.

Biologists and medical professionals use "chance" and probabilities in this second, classical sense. (For example, the chance that a disease will recur in a patient.) In evolutionary biology, a "chance" event is simply an event which is not caused by the organism itself, and which we could not have predicted given our limited knowledge of the initial conditions, which affects the organism's survival (e.g. a natural disaster) or its genetic information (e.g. a mutation). "Chance" in evolution, or any other scientific theory, is a semi-quantitative statement about our ignorance --- our lack of precise knowledge of the initial conditions, or our lack of understanding of how a particular final state is selected.

(For more information on this topic, see the Chance and Evolution FAQ by John Wilkins.)

How can "chance" events be compatible with God's providence?

The use of the term "chance" in any scientific theory is not, strictly, a statement about causation (or lack of causation); rather, it is a statement about our lack of knowledge about causation. Events which appear random from our (human) perspective need not be uncaused from a divine, transcendent perspective. On the contrary, theistic philosophy has always maintained that God can and does determine the outcome of "chance" events. (Proverbs 16:33, "The lot is cast into the lap, but its every decision is from the Lord." NIV)

The purpose of this FAQ is not to argue that chance events must be seen from a theistic perspective. Likewise, this FAQ is not intended to argue that macroevolution must be true or that "evolutionary creationism" is preferable to various versions of "progressive creationism." The purpose of this FAQ is merely to point out that the element of chance in microevolution, macroevolution, or any other scientific theory is in no way antithetical to the traditional theology of God's providential control.

A number of scientists, who have both a solid scientific understanding of "chance" and a thorough understanding of the Christian doctrine of Providence, have written essays on this topic. Donald MacKay [1978, 1988] and John Polkinghorne [1989] offer two excellent perspectives.

Donald MacKay's perspective

MacKay explains that events which are fundamentally unpredictable from human perspective (e.g. the outcomes of quantum measurements) need not be undetermined from God's perspective. He begins by rejecting the idea of a universe which can run "on its own" without God, instead suggesting the idea of "dynamic stability." The apparent stability of the matter particles and fields of the universe is not an intrinsic property; rather, it is due to the continual, dynamic, sustaining activity of God. MacKay uses the analogy of a game of PONG played on a television screen. Although the paddles, ball, and walls on the television screen appear to be stable objects, we know that, in fact, the screen is continually bombarded by electron beams and the images of the objects are refreshed dozens of times per second in a dynamic process which gives the illusion of intrinsic stability.

MacKay writes that one of the goals of science -- perhaps its main goal -- is to understand the causal connections between events. God is not a "missing link" in an otherwise complete chain of causal events; rather, God is the basis for the whole chain. Again, he uses the PONG analogy. By observing the way the ball bounces off the paddles and walls, we may develop "laws" for the motion of the ball. But we know that the underlying basis for its motion is the programming in the black box that sits in front of the television. It would be premature to conclude that -- once we know the laws of the behavior of the paddles and the ball -- the black box is unnecessary!

The theistic perspective of dynamic stability neatly removes any metaphysical teeth from the word "Chance." A physical event which is not completely predictable by its initial conditions, such as the result of a quantum measurement, is neither meaningless nor uncaused. The outcome is still very much under God's control; we simply cannot fully predict it.

John Polkinghorne's perspective

Polkinghorne offers a perspective which is different from and complementary to MacKay's. Polkinghorne moves quickly past any consideration of quantum mechanics or "dynamic stability." Instead, he discusses how modern understandings of "chaos" allow the possibility for God to affect the outcomes of stochastic processes without contravening the ordinary laws of nature and without necessarily "pulling invisible deterministic strings" during every chance event.

Polkinghorne begins by stressing that chance and necessity go hand-in-hand. "Random" events occur within systems which both constrain the choices and respond to the choices made. For example, random meetings of pre-biotic organic molecules happen within a system of natural laws, laws which were designed by the Creator to favor certain combinations. In the same way, genetic mutations can be thought of as small-step explorations of large-dimensional "genomic phase space" which was also designed by the Creator. Polkinghorne writes [1989: 38ff],

"Necessity is the regular ground of possibility, expressed in scientific law. Chance, in this context, is the means for the exploration and realization of inherent possibility, through continually changing (and therefore at any time contingent) individual circumstances. It is important to realize that chance is being used in this `tame' sense, meaning the shuffling operations by which what is potential is made actual. It is not a synonym for chaotic randomness, nor does it signify just a lucky fluke.... I am still deeply impressed by the anthropic potentiality of the laws of nature which enable the small-step explorations of tamed chance to result in systems of such wonderful complexity as ourselves."

Second, Polkinghorne notes that if the laws of necessity --- the playing field upon which shuffling operations of "chance" must operate --- are designed, the ultimate outcome need not be unforeseeable or arbitrary. [1989: 40]

"It is from this inter-relationship [between chance and certainty] that order rises out of chaos, as we see exemplified in the behaviour of dissipative systems which converge on to predictable limit cycles, approached along contingent paths.... To acknowledge a role for tame chance is not in the least to deny the possibility that there is a divinely ordained general direction in which the process of the world is moving, however contingent detailed aspects of that progression (such as the number of human toes) might be."

Third, Polkinghorne notes that the sensitivity and open flexibility of "chaotic" systems allows God one way to subtly, yet effectively, interact with his creation. For example, one could imagine God "tweaking" microscopic events to cause macroscopic results; but Polkinghorne has something much less crude in mind. He calls attention to our own, human, ability to choose and to act. Although certain "bottom-up" principles (physical laws such as the conservation of energy) constrain the way our brains work, the great sensitivity and flexibility of such complex systems allow the possibility for certain "top-down" organizing principles (e.g. our sense of consciousness, free will) to have significant effects (without contravening physical law). Polkinghorne does not speculate how this might actually work within our brains; those answers are still well beyond our understanding. He does, however, point out that the open flexibility of complex systems allows for the possibility of such "top-down" principles. Polkinghorne uses this as an analogy for how God might also use "top-down" principles in his personal interaction with his creation.

In summary, Polkinghorne emphasizes that the universe is not a universe of clock-work determinism. From a theistic perspective, the interplay of chance and necessity which we see scientifically suggests that the universe is so constructed that (1) God can act personally within it; (2) human beings may exercise their free will within it; (3) the universe can explore its own freedom and potential by an evolving process.

Conclusion

In closing, I should note that MacKay and Polkinghorne do not wish to restrict God to this sort of "subtle" action. Both authors write about miracles, but that is outside the scope of this FAQ. The point of both authors, for this FAQ, is that "random" events (whether described by physics, evolutionary biology, or any other science) are in no way an obstacle to God's providential action; quite the opposite, they are one way in which God could exert providential care.

Acknowledgements

Thanks for John Wilkins for his encouragement to write this FAQ. See also the Chance and Evolution FAQ.

For another philosophical discussion, see the Evolution and Metaphysics FAQ.

Bibliography

MacKay D M Science, Chance, and Providence Oxford UP 1978

MacKay discusses how events which are fundamentally unpredictable from human perspective (e.g. the outcomes of quantum measurements) need not be undetermined from God's perspective.

MacKay D M The Open Mind and Other Essays Inter-Varsity Press 1988

Contains most of the content of Science, Chance, and Providence, and is more widely available.

Polkinghorne J C Science and Providence Shambhala Publications 1989

Polkinghorne discusses how modern understandings of "chaos" allow the possibility for God to affect the outcomes of "chance" events without contravening the ordinary laws of nature.

Copyright © 1996 by Loren Haarsma

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