The Problem of Evil - Common Sense Atheism

82 The Global Argument Continued
both the Cartesian and the Thomist conceptions of omnipotence. A
being that is omnipotent in the Cartesian sense is able to do intrinsically
impossible things; a being that is omnipotent in the Thomist sense
is, as it were, excused from the requirement that it be able to do
things that are intrinsically impossible. This suggests a solution to the
problem of free will and divine foreknowledge: why should we not
qualify the ‘‘standard’’ definition of omniscience in a way similar to
that in which St Thomas, if you will forgive the prolepsis, qualified
the Cartesian definition of omnipotence? 8 Whynotsaythatevenan
omniscient being is unable to know certain things—those such that its
knowing them would be an intrinsically impossible state of affairs. Or
we might say this: an omnipotent being is also omniscient if it knows
everything it is able to know. Or if, as I prefer, we frame our definition
of omniscience in terms of belief and the impossibility of mistake: an
omnipotent being is also omniscient if it is impossible for its beliefs
to be mistaken and it has beliefs on every matter on which it is able
to have beliefs. (The way that had to be worded is rather complicated;
perhaps an example will make its point clearer. Suppose that today
I made a free choice between lying and telling the truth, and that I
told the truth. Suppose that this proposition is logically inconsistent
with the proposition that yesterday a being whose beliefs cannot be
mistaken believed that today I should tell the truth. Then any being
whose beliefs cannot be mistaken must yesterday not have believed that
today I should tell the truth; and, of course, it can’t be the case that
yesterday it believed that today I should lie. That is, such a being must
yesterday have had no beliefs about what I should do freely today. And if
that being was also omnipotent, it was unable, despite its omnipotence,
then to have or then to acquire beliefs about what I should freely do
today. To ask it to have or to acquire any belief about my future free
actions would be to ask it to bring about a metaphysically impossible
state of affairs.)
This qualification of the ‘‘standard’’ definition of omniscience is in
the spirit of what I contended in the second lecture were permissible
revisions of the properties in our list of divine attributes—or of our
accounts of them. If we say, first, that the omnipotent God is omniscient
in this sense: he knows everything that, in his omnipotence, he is able to
know, and, secondly, that he does not know what the future free acts of
any agent will be, we do not, for the reasons I have just given, contradict
ourselves. I propose then that we revise our earlier definition in just