Theism and Explanation - Appeared-to-Blogly

Appendix 151
explanation is a causal explanation. For an intention is a mental state—a
species of pro attitude—which can rightly be described as the cause of the
agent’s behaviour. And just as the act of accepting a proposition can be a
voluntary act, even though forming a belief is not, so the act of forming an
intention can be a voluntary act, even though having a desire is not. 21
An intentional explanation explains an act as the most rational way of
enacting an intention, given a certain set of beliefs. But our desire for explanation
may go further than this. I have argued that an explanation that
posits an intention and explains the agent’s behaviour in the light of it is
an intentional explanation. It doesn’t need to do anything else (1.3.3): the
action is explained by invoking the relevant intention. But we might want
to go further and to explain its explanans. After all, the formation of an
intention is a mental event, and the resulting intention a mental state. So it
is perfectly reasonable to ask after the causes of this event. 22 At that point,
pace Swinburne, it does seem appropriate to cite “some . . . state of the
agent or some event involving him.” 23 Even if an intention is a sui generis
mental state, and even if the formation of an intention is an act on the part
of the agent, we can still ask why an agent formed this intention rather than
another. It is at this point that we will need to invoke the agent’s beliefs and
desires. 24 How would invoking his beliefs and desires explain his intention?
That’s a question I shall address shortly (Appendix 2.2).
A.1.3 The Rationality Principle
So an intentional explanation posits an agent having a particular intention,
as well as a set of beliefs relevant to its attainment, and shows that
the action in question is a rational one, given that intention. And if we
want to explain the explanans, then we will need to show that this was a
reasonable intention to form, given the agent’s other beliefs and desires.
This talk of what is “rational” or “reasonable” highlights a central feature
of intentional explanations, namely their reliance upon what I have called
the rationality principle (5.2). This principle is best thought of as a presumption
of rationality, comparable to the legal presumption of innocence
or what I have called the scientist’s “presumption of naturalism” (7.3 and
8.2). We explain an agent’s action by positing a particular intention and
by offering a practical syllogism that has a description of that action as its
conclusion. But to do this is to presume that the agent is acting rationally.
If that presumption turns out to be false, then an intentional explanation
cannot be given.
Let me examine this rationality principle a little more closely. A useful
place to start is with Dan Dennett’s discussion of what he calls “the
intentional stance.” Dennett argues that there are three strategies we can
adopt when attempting to predict the behaviour of any system. The fi rst
of these is the physical stance: “if you want to predict the behavior of a
system, determine its physical constitution . . . and the physical nature of