Theism and Explanation - Appeared-to-Blogly

34 Theism and Explanation
3.1 THEORETICAL EXPLANATIONS
Let’s start with the least controversial of my preliminary claims. Any proposed
theistic explanation is a theoretical explanation. The believer posits
the existence and action of an unobservable agent, namely God, in much
the same manner as the physicist posits the existence of unobservable entities,
in order to explain some observable fact about the world. Such explanations
are common in the sciences. A striking example is J. J. Thomson’s
1897 paper on cathode rays. 2 The paper sets out to decide between two
hypotheses as to the nature of these rays. According to the fi rst, they represent
a wave motion in the aether. According to the second, they represent
streams of electrically-charged particles, particles which in due course
would come to be called “electrons.” 3 As I shall argue later (6.2.1), at least
some of Thomson’s arguments in support of the electron hypothesis are
classic instances of abductive reasoning. For the moment, I wish only to
note that the particles whose existence he was positing were inaccessible to
observation, even with the aid of instruments. If we accept the legitimacy of
Thomson’s reasoning, one possible objection to proposed theistic explanations
may be dismissed immediately. Whatever else may be said about such
proposed explanations, they are not illegitimate merely because the being
whose existence they posit cannot be observed.
3.1.1 The Legitimacy of Theoretical Explanations
The existence of theoretical explanations is not a matter of dispute. Scientists
apparently feel no qualms about positing the existence of unobserved
entities, in order to explain some phenomena. And some such explanations
have been stunningly successful. 4 As J. J. Thomson’s discovery reminds us,
they have been widespread within the fi elds of physics and chemistry, where
scientists posit the existence of atoms and subatomic particles. But an historical
science, such as evolutionary biology, must also posit unobserved
entities and causal processes. It is true that these are unobserved rather
than unobservable. If an observer were to live for long enough, she would
presumably witness natural selection at work. But the particular processes
that gave rise to the living beings we see around us occurred so long ago,
and over such an extended period of time, that they are in practice inaccessible
to observation.
So there is no dispute about the existence or the success of theoretical
explanations. They are widely used by scientists and they work. What is a
matter of dispute, at least among philosophers, is the ontological status of
the unobserved (or unobservable) entities which these explanations posit.
On the one hand, there are contemporary philosophers who defend a realist
understanding of theoretical explanations. 5 Following in the footsteps of
Thomson, they believe that atoms, molecules, and electrons actually exist.
More precisely, they believe that the success of the explanations that invoke