Different Understandings of Chance
The word ‘chance’ is generally used in one of three ways:
-
in respect of an event such as the
tossing of a coin. As Peacocke says, ‘had we sufficient knowledge of the exact
values of all the relevant parameters, the laws of mechanics would in fact
enable us to say in any particular toss which way the coin would fall.’Thus to call such outcomes chance is to confess to the incompleteness of our knowledge of the relevant causative
factors, it is not to deny that those factors exist or that they are sufficient
to account for the event.
-
in respect of combinations of events
which seem to come from two different causal chains. Peacocke again: ‘Suppose
that when you leave the building in which you are reading these pages, as you
step on to the pavement you are struck on the head by a hammer dropped by a man
repairing the roof... the two trains of events... are each within themselves
explicable as causal chains. Yet there is no connection between those causal
chains except their point of intersection.’
If Laplace were right, and
the whole course of the universe theoretically predictable (see determinism, indeterminism and their implications), then of
course this hammer-blow would also be predictable. This second meaning of chance would again be an expression of our
ignorance.
-
as a non-technical way of describing
the outcomes of events governed by quantum theory. Quantum mechanics, as
usually understood, implies that these outcomes are not determinate until they occur - they can only be expressed in
terms of probabilities. Not only is our knowledge of systems limited by the
Heisenberg Uncertainty Principle, but there is an inalienable indeterminacy
about the events themselves (see Shaking the Foundations: the implications of
quantum theory). Polkinghorne has argued that there is indeterminacy also in
large-scale chaotic systems.
Meaning ii) has an enormous effect on how
the world actually develops - most strikingly in the field of biological
evolution. Darwin’s evolutionary schemepostulates that the environment, viewed as an independently changing entity, is
at every moment selecting which variants (arising by a largely separate causal
chain) will survive and prosper. Contemporary thinking would recognise the
situation as much more complex than that: the environment is itself being
shaped by the activities of species as they evolve (this is strikingly illustrated
by the Gaia Hypothesis).
But the point still has force - most dramatically in respect of the great
extinctions. The trajectory of the massive object that collided with the
Yucatan Peninsula 60 million years ago clearly belonged to a different causal
chain from the one that had given rise to dinosaurs vulnerable to the extreme
conditions resulting from the collision. So the course of evolution is highly
unpredictable, much influenced by this sort of chance.
But it is meaning iii) of ‘chance’ which
offers the ontological indeterminacy,
the openness to possible influence from outside the structure of physical law,
that has been of such interest to theologians. It seems to offer a possibility
other than God banished, before or behind:
that is, the possibility of a God who is ‘before’ in the sense of being the
initial cause of everything, ‘behind’ in the sense of sustaining the laws and
regularities God has established, but also a God working through the
openness and indeterminacy of the natural order.
The debate about divine action has to be
taken as a whole - any Christian-theological account of God’s activity must
include reference to creation and to eschatological redemption - but there is a
specific sub-debate, much aired in recent years, on the possibility of God’s
particular action in situations in
the present. Clayton makes the important point that any such particular
action must be congruent with God’s action in universal history as a whole.We cannot postulate a God faithful in upholding the regularities of the cosmos,
but capricious in particular providential action.
Email
link | Feedback | Contributed by: Dr.
Christopher Southgate
Source: God, Humanity and the
Cosmos (T&T Clark, 1999)
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