Theism and Explanation - Appeared-to-Blogly

Successful Theistic Explanations 133
Swinburne adopts what we may call a “metaphysical” conception of simplicity.
68 The simplicity of a theory, he writes,
is a matter of its postulating few (logically independent) entities, few
properties of entities, few kinds of entities, few kinds of properties,
properties more readily observable, few separate laws with few terms
relating few variables, the simplest formulation of each law being mathematically
simple. 69
This is a very broad defi nition indeed, and its application to theism is problematic.
70 Is God really, as Swinburne argues, “the simplest kind of person
there could be?” 71 As we have seen (3.3.1), there does exist a theistic doctrine
of divine simplicity, which in some form or other Swinburne wishes
to endorse. 72 But one could argue, with Cleanthes (and Plantinga), 73 that
this doctrine is incompatible with the idea that God is a personal agent.
And what about the doctrine of the Trinitarian nature of God? Is this compatible
with the idea that God is “the simplest kind of person there is?” 74
Perhaps it is, but the theist at least has a case to answer here.
7.4.1 Auxiliary Hypotheses
Swinburne’s criterion of simplicity is closely related to what I shall call
“ontological economy,” and which I shall discuss in a moment (7.5). I favour
a rather different defi nition of simplicity, which is broadly Popperian in fl avour
and which is most clearly expressed in the work of Paul Thagard. Karl
Popper offers what at fi rst sight seems an idiosyncratic defi nition of simplicity.
The simplicity of a theory, he suggests, is equivalent to its empirical
content or degree of falsifi ability. 75 Building on this foundation, Thagard
argues that simplicity has to do with the number of auxiliary hypotheses
that a theory requires in order to explain the fact in question. The fewer the
auxiliary hypotheses, the simpler the theory.
Note how Thagard’s conception of simplicity differs from Swinburne’s.
Thagard does not argue that one theory (T 1 ) should be preferred to another
(T 2 ) simply because T 1 postulates the existence of fewer entities. In fact,
he argues that we may prefer a theory that postulates more entities than
its competitors if it has greater explanatory power or, in Thagard’s terms,
if it contributes to consilience. 76 The important fact—that which makes a
theory simple in Thagard’s sense—is that it contributes towards consilience
“without making a host of assumptions with narrow application.” 77
At fi rst sight, Thagard’s conception of simplicity may seem different
from Popper’s, but in fact the two are closely related. For a theory that is
preserved from refutation only with the aid of auxiliary hypotheses loses
empirical content. It is, in Popper’s terms, less falsifi able and to this extent
more complex. 78 This account of simplicity, as developed by Thagard, seems
more workable than Swinburne’s conception, which requires us to count
the number of entities or principles a theory employs. Any such count will