Theism and Explanation - Appeared-to-Blogly

Potential Theistic Explanations 79
open to a divine agent. Since I have yet to discuss the role of modal judgements
in proposed theistic explanations, I shall examine this form of the
sceptical objection later, under the heading of “modal scepticism” (5.4.3).
But the outcome of each of these two forms of scepti cism—theological and
modal—is the same. If we cannot make such judgements, then the in principle
objection is correct: an account of divine action cannot be even a
potential explanation, of any state of affairs. End of story.
5.1.1 Design Arguments
A contemporary expression of theological scepticism can be found in the
work of Elliot Sober. Sober employs his theological scepticism in order to
argue against intelligent design theory. But his sceptical objections are applicable
to any kind of proposed theistic explanation. So his arguments against
intelligent design will make a useful starting point for my discussion.
Like Robin Collins and Richard Swinburne (2.1.3.1), Sober makes use of
confi rmation theory in order to analyse the theist’s arguments. He argues
that the design argument is most plausibly understood to rely on the “likelihood
principle.” This principle reads:
Observation O supports hypothesis H 1 more than it supports hypothesis
H 2 if and only if Pr(O|H 1 ) > Pr(O|H 2 ). 4
In most forms of design argument, hypothesis one (H 1 ) is assumed to be
design and hypothesis two (H 2 ) is thought to be chance. One might, of
course, argue that chance is not the only alternative to design. Since 1859
we have had an alternative, at least in the case of biological systems, namely
natural selection. But the advocates of intelligent design (against whom
Sober is writing) argue that the Darwinian hypothesis cannot do the job,
that it is not even a potential explanation of the complexity and diversity
of living organisms. This, they believe, justifi es their view that the only
alternative is chance. 5 So if O represents the observed fact, C represents the
chance hypothesis, and D represents design, their argument rests on the
following claim:
Pr(O|D) > Pr(O|C).
In other words, they argue that the observed facts are more likely given the
hypothesis of design than given what they regard as the only alternative,
namely chance.
5.1.2 No Victory by Default
Sober’s response to this claim makes two points. First of all, he argues that
the design hypothesis (if it is a hypothesis) does not win by default. To claim
victory for a design hypothesis, it is not enough to show that Pr(O|C) is very