It is a time of many times: a time for dancing, even if to the songs of a foreign land; a time for walking together, unintimidated when we seem to be a small and beleaguered band; a time for rejoicing in momentary triumphs, and for defiance in momentary defeats; a time for persistence in reasoned argument, never tiring in proposing to the world a more excellent way. ~Richard Neuhaus
Sunday, March 26, 2017
The Gale-Pruss cosmological argument for the existence of God
Richard Gale and Alexander Pruss have advanced an
interesting update on the traditional Cosmological Argument for the existence
This argument begins with some definitions.
A possible world
is a “maximal, compossible conjunction of abstract propositions. It is maximal
in that, for every proposition p, either p is a conjunct in this conjunction or
its negation, not-p, is, and it is compossible in that it is conceptually or
logically possible that all of the conjuncts be true.”[ii]
The Big Conjunctive
Fact for a possible world consists of the conjunction of all of the
propositions that would be true if that world were the actual world. Some of these are necessarily true. But the
Big Conjunctive Fact of each possible world also contains propositions that are
contingently true- true in some possible worlds and not in others. Each
possible world contains a unique conjunction of contingent propositions. Gale-Pruss
refer to this as the Big Conjunctive Contingent
Fact, or BCCF. It is the BCCF of a world that individuates that world,
distinguishing it from all other possible worlds. Let p be the BCCF of the actual world.
Is there an explanation for p- an explanation for why this particular set of contingent facts
is the case, rather than not?
At this point the defender of a traditional Cosmological
Argument would introduce the Principle of Sufficient Reason:
For every proposition, p, if p is
true, then there is a proposition, q, that explains p.
But it may not be reasonable to expect the skeptic to accept
this principle. In its stead, Gale-Pruss offer a weaker form of the Principle
of Sufficient Reason:
For any proposition, p, if p is
true, then it is possible that there
exists a proposition, q, such that q explains p.
Unlike traditional cosmological arguments, Gale-Pruss’
argument does not require us to assume that there actually is an explanation for p. It only needs to be possible that there is such an explanation. Gale-Pruss assert that
it is: There is some possible world, W1, in which p is true,and in W1, some proposition q is true,
and q explains p.
Now, are W1 and the actual world the same world? Gale-Pruss
insist that they are. For p is the Big Conjunctive Contingent Fact of the actual
world; p is true in W1, and the BCCF of a given world is what individuates it. Therefore,
there is some proposition q that is true in the actual world and explains p,
the BCCF of the actual world. Now, what sort of explanation is it?
According to Gale-Pruss there are only two kinds of
explanation: Scientific, and personal. Personal explanations are explanations
in terms of the intentions of some person. But q cannot be a scientific explanation.
A scientific explanation “must contain some law-like proposition, as well as a
proposition reporting a state of affairs at some time.”[iii]
But these are contingent propositions, and therefore members of p. Yet they
purport to explain p, as well as each proposition contained within p, which
means they would explain themselves, and this is impossible.
Therefore q must be a personal explanation. Now what sort of
person does q invoke? It cannot be a contingently existing being, since a
proposition asserting the existence of a contingently existing being would be
part of p and once again, q would explain itself. So q explains p, the Big Conjunctive
Contingent Fact of the actual world, by reference to the intentional action of
a necessary being. The proposition q, then, asserts something like this:
exists a necessary being who intentionally creates the world.”[iv]
Gale-Pruss treat q as though it is not one of the
member-conjuncts of p. This is well motivated. For one thing, if q were
contained within p, the Big Conjunctive Contingent Fact of the actual world,
then q would be part of the very state of affairs that it hopes to explain. But
worse than this, to define p as the BCCF of the actual world, and then to presume
that q is contained within p, is to presume at the outset that the actual world
is explained by the intentions of a necessary being, and this is what the
argument seeks to prove.
And yet, as Gale-Pruss acknowledge, q is a contingent
and so prima facie, one would think
that for any possible world, either it, or its negation, is a member-conjunct
of that world’s Big Conjunctive Contingent Fact.[vi]
But let us set this observation aside and follow Gale-Pruss in treating q as
though it is not contained within p.
Since q is a contingent proposition, there are possible
worlds in which it is not true. That means that in addition to W1, which
contains p and in which p is explained by q, there is another possible world,
W2, which contains p, and in which p is not
explained by q, because it is not true in W2 that there is a necessary being
who intentionally creates that world. As it turns out, if a Big Conjunctive
Contingent Fact does not contain either q, or its negation, then pace Gale and Pruss, it does not
individuate a possible world.
This means that a world’s containing p does not imply that
it is identical with the actual world. Gale and Pruss are not entitled to infer,
from the fact that p is true in W1, that W1 is identical with the actual world,
since p is true in W2 as well.
The actual world is identical with one of these worlds, W1 or
W2, but the Gale-Pruss argument leaves us with no reason to prefer one over the
other. Since they hoped to prove that the existence of the actual world is
explained by the intentions of a necessary being, and they can do this only if
they can show that the actual world is identical with W1 rather than W2, Gale
and Pruss’ argument fails.
Department of Philosophy
New Cosmological Argument,” Richard M. Gale and Alexander R. Pruss; Religious
Studies, vol 35, Number 4 (Dec 1999), pp. 461-476
New Cosmological Argument,” p. 461. For a more detailed explanation of the
notion of a possible world, see https://plato.stanford.edu/entries/possible-worlds/.
Gale-Pruss realize that they have not proven the existence of the God of
Western theism, since they have not proven that this being is omniscient,
omnipotent, and benevolent. They require only that God be powerful enough to
create the actual world. But they think- and I agree- that their more limited
conclusion is still an interesting one.
seems likely that Gale-Pruss are thinking of q as having some kind of special
status that sets it apart from ordinary contingent facts. Perhaps they wish to
say that it is a supernatural fact,
because it reports the intentions of a necessary being. (On p. 468 they claim
that a necessary being is a supernatural one.) In this case p is really the Big
Conjunctive Contingent Natural Fact.
I do not have space to pursue this suggestion here, which does not, in any
case, seem to affect my analysis.