Theism and Explanation - Appeared-to-Blogly

Successful Theistic Explanations 129
in certain circumstances one could be justifi ed in positing the existence of
an unembodied agent, in this case a poltergeist. But the prior probability
of this hypothesis will be diminished by the fact that such an agent is very
different from the other agents with which we are familiar. 51 And one of
these differences is precisely the fact that a poltergeist would be an unembodied
agent. 52 So far, so good. Up to this point, Swinburne and Mackie
are in agreement. But Swinburne also argues that the theistic hypothesis is
an exception to this rule: in this case, he suggests, we do not need to take
such considerations into account.
Why not? With regard to any theory, Swinburne argues that the signifi
cance of background knowledge decreases as the scope of our theories
increases. “More and more of the observational evidence falls into the category
of data that the theory needs to explain, rather than data that it takes
for granted in explaining other things.” 53 In the case of a theory of wide
scope, we should not demand that the entities whose existence it posits
resemble those that the theory is meant to explain. As Swinburne writes,
“it is no objection to some theory of physics postulating fundamental particles
and purporting thereby to explain the physical and thereby chemical
behaviour of medium-sized objects that it postulates particles quite unlike
those medium-sized objects.” 54 But as a hypothesis that seeks to explain
the very existence of universe, theism is a hypothesis of the widest possible
scope. 55 It follows that there is no background knowledge, other than
purely logical knowledge, with which it has to fi t. The theist does not need
to worry about the fact that his posited personal agent is so different from
any other with which we are familiar.
This is a very odd argument. It is made still more puzzling by the revelation
that Swinburne has stipulated what is to count as background
knowledge. Within the framework of confi rmation theory that Swinburne
employs, the relevant distinction is not (as it is for me) between the
explanandum and background knowledge, but between new evidence and
background evidence. 56 And Swinburne argues that
the division between new evidence [e] and background evidence [k] can
be made where you like—often it is convenient to include all evidence
derived from experience in e, and to regard k as being what is called in
confi rmation theory mere “tautological evidence,” that is, in effect all
our other irrelevant knowledge. 57
Well, it may well be “convenient” to make the division in this way. (For
one thing, it makes it easier to set aside considerations that might lower
the prior probability of theism.) But given that we are apparently free to
choose, is this the most natural way to divide the evidence?
No, it is not. 58 The key question here is: Which facts about the world fall
within the scope of the proposed explanation? Those that do fall within
the scope of the explanation constitute the relevant evidence (e); those that