Theism and Explanation - Appeared-to-Blogly

112 Theism and Explanation
they seemed to be acting rationally in doing so. So my preferred answer to
this question is the explanationist one. According to the explanationist,
we may be acting rationally in accepting a theory even if we do not have
suffi cient evidence to demonstrate that it is probably true. What we should
require of such a theory is that it display, to a greater degree that any competitor,
certain explanatory virtues. It is true that it may be impossible
to quantify such judgements. (Hence the attraction of Bayesian formulas.)
And there may exist no algorithm, no decision procedure that will ensure
that our judgements are correct. As Alan Musgrave remarks, in choosing
one theory over another “two scientists may make their choices in different
ways” and yet in doing so both of them might be acting rationally. 49
But something like the explanationist view does seem to underlie our best
scientifi c practice.
6.2.3 Explanatory Virtues
If we adopt the explanationist view, then two questions arise. The fi rst is:
What features of theories count as explanatory virtues? The second is: Why
do we regard these features as virtues, or desiderata? Let me begin with
the fi rst of these questions. In assessing the comparative merit of scientifi c
theories, scientists and philosophers commonly refer to qualities such as
explanatory power, simplicity, economy, precision, informativeness, and
elegance. The problem here is that each of these qualities is notoriously diffi
cult to defi ne, there exists no exhaustive list, and it is far from clear just
how they are supposed to function.
Let me begin with the last point, namely, how such virtues are supposed
to function. William Lycan distinguishes three roles that explanatory
virtues may be thought to play. They may be thought of as purely
descriptive, as an account of how scientists in particular actually choose
theories. Or they may be thought of as normative, as accounts of how
we would choose theories, if we were acting rationally. Or they may be
regarded as practical suggestions, part of what Alvin Goodman calls a
“doxastic decision procedure.” 50 In what follows, I shall be taking them
primarily as normative, as criteria which distinguish justifi ed from unjustifi
ed explanatory claims, although insofar as they can be applied to real
cases, they also form part of a decision procedure, showing how we could
make such choices.
Why are these features desiderata? What makes them explanatory virtues?
I don’t think I have a satisfactory answer to this question, but then
I’m not sure if anyone else does, either. I began by asking what would give
us suffi cient reason to accept a potential explanation as the actual one. And
my reply was that we have reason to accept such a hypothesis if it is the best
explanation on offer. If it has no competitors, then we have reason to accept
it if it possesses, to some acceptable degree, those qualities by which we