Theism and Explanation - Appeared-to-Blogly

Appendix 165
this is the explanation we should accept, it needs to be corroborated. So
you make a prediction.
(1) If Sally intends to get fresh air, then—all things being equal—she will
open the window.
If she does open the window, your hypothesis is corroborated.
But what if she doesn’t? What if Sally continues to move around the
room, looking uncomfortable, but makes no move towards the window?
What then? Well, you could immediately abandon your hypothesis. Or you
could amend it to “save the appearances.” You could, for instance, conjecture
that although Sally intends to get fresh air, she does not want to let
in the street noise. After all, your initial hypothesis had a ceteris paribus
(“other things being equal”) clause. So you can now argue that other things
were not equal. 73 So your explanation will now read as follows.
(2) Sally is moving around the room because she intends to get fresh air.
She is not opening the window because she believes this would let in the
street noise and does not want to disturb her colleagues’ discussion.
The second sentence represents an auxiliary hypothesis, invoked to
save the appearances. But it posits new beliefs and desires, and this posit
requires corroboration in turn: it should not be a merely ad hoc amendment
in order to save your theory. Sometimes it will be possible to corroborate
this new posit directly, by using it to make a new prediction that is independent
of those made by the original hypothesis. Let’s say, for instance,
you were to explain Sally’s not opening the window by suggesting she has a
pathological fear of heights and believes that if she glanced out the window
she would suffer from vertigo. This belief-desire set represents a disposition
which you would expect to be operative on other occasions. So you could
use it to predict how she will act on other occasions. You could predict that
Sally will always avoid windows in tall buildings, so far as she can, or that
she will avoid climbing ladders.
Sometimes, however, the new belief-desire set may be too closely tied to
the particular situation to allow for entirely independent corroboration.
Here the best you can do is to test the amended hypothesis in its entirety.
You can do so by using it to make a prediction which it would not support,
were it not for the newly-posited belief and desire. How could you
do this, in the case in hand? Well, you could predict that Sally will fi nd
some other way of getting fresh air, perhaps by making an excuse, going
downstairs, and leaving the building. The line of reasoning would then
be as follows.
(3) If Sally intends to get fresh air, but believes that by opening the window
she would let in the horrible street noise, she will fi nd an excuse
to leave the building.