The Kalam Cosmological Argument
William Lane Craig
...I find the kalam cosmological argument for a temporal first cause of the universe
to be the most plausible argument for God’s existence. I have defended this
argument in two books, The Kalam Cosmological Argument and The Existence of
God and the Beginning of the Universe. Let me explain and supplement what I say
there. The argument is basically this: both philosophical reasoning and scientific
evidence show that the universe began to exist. Anything that begins to exist
must have a cause that brings it into being. So the universe must have a cause.
The argument may be formulated in three simple steps:
- Whatever begins to exist has a cause.
- The universe began to exist.
- Therefore, the universe has a cause.
The logic of the argument is valid and very simple: it is the same as when we
reason, “All men are mortal; Socrates is a man; therefore, Socrates is mortal.” So
the question is, are there good reasons to believe that each of the steps is true? I
think there are.
Whatever Begins to Exist Has a Cause
The first step is so intuitively obvious that I think scarcely anyone could sincerely
believe it to be false. I therefore think it somewhat unwise to argue in favor of it,
for any proof of the principle is likely to be less obvious than the principle itself. And
as Aristotle remarked, one ought not to try to prove the obvious via the less
obvious. The old axiom that “out of nothing, nothing comes” remains as obvious
today as ever. In a sense, I find it an attractive feature of this argument that it
allows the atheist a way of escape; he can always deny the first premise and
assert that the universe sprang into9 existence uncaused out of nothing. For he
thereby exposes himself as a man interested only in an academic refutation of the
argument and not in really discovering the truth about the universe.
The late J.L. Mackie appears to have been such a man. In refuting the kalam
cosmological argument, he turns his main guns on this first step: “there is a priori
no good reason why a sheer origination of things, not determined by anything,
should be unacceptable, whereas the existence of a god [sic] with the power to
create something out of nothing is acceptable.” 1 Indeed, creation ex nihilo
raises problems: (i) If God began to exist at a point in time, then this is as great a
puzzle as the beginning of the universe. (ii) Or if God existed for infinite time, then
the same arguments would apply to His existence as would apply to the same
arguments would apply to His existence as would apply to the infinite duration of
the universe. (iii) If it be said that God is timeless, then this, says Mackie, is a
complete mystery.
Now notice that Mackie never refutes the principle that whatever begins to exist
has a cause. Rather, he simply demands what good reason there is a priori to
accept it. He writes, “As Hume pointed out, we can certainly conceive an uncaused
beginning-to-be of an object; if what we can thus conceive is nevertheless in some
way impossible, this still requires to be shown.” 2 But, as many philosophers have
pointed out, Hume’s argument in no way makes it plausible to think that something
could really come into being without a cause. Just because I can imagine an
object, say a horse, coming into existence from nothing, that in no way proves
that a horse really could come into existence that way. The defender of the kalam
argument is claiming that it is really impossible for something to come uncaused
from nothing. Does Mackie sincerely believe that things can pop into existence
uncaused, out of nothing? Does anyone in his right mind really believe tht, say a
raging tiger could suddenly come into existence uncaused, out of nothing in this
room right now? The same applies to the universe: if there were originally
absolute nothingness–no God, no space, no time–how could the universe possibly
come to exist?
In fact Mackie’s appeal to Hume at this point is counterproductive. For Hume
himself clearly believed in the causal principle. In 1754 he wrote to John Stewart,
“But allow me to tell you that I never asserted so absurd a Proposition as that
anything might arise without a cause: I only maintain’d, that our Certainty of the
Falsehood of that Proposition proceeded neither from Intuition nor Demonstration,
but from another source.”3 Even Mackie confesses, “Still this [causal] principle
has some plausibility, in that it is constantly confirmed in our experience (and also
used, reasonably, in interpreting our experience.)4 So why not accept the truth of
the causal principle as plausible and reasonable–at the very least more so than its
denial?
Because, Mackie thinks, in this particular case the theism implied by affirming the
principle is even more unintelligible than the denial of the principle. But is this really
the case? Certainly the proponent of the kalam argument would not hold (I) tht
God began to exist or (ii) that God is, prior to creation, timeless? I would argue
that God exists timelessly prior to creation and in time subsequent to creation.
This may be “mysterious” in the sense of “wonderful” or “awe-inspiring,” but it is
not, so far as I can see, unintelligible; and Mackie gives us no reason to think that it
is. It seems to me, therefore, that Mackie is entirely unjustified in rejecting the first
step of the argument as not intuitively obvious, implausible, and unreasonable.
The Universe Began to Exist
I we agree that whatever begins to exist has a cause, what evidence is there to
support the crucial second step in the argument, that the universe began to exist?
I think that this step is supported by both philosophical arguments and scientific
confirmation of those arguments.
Philosophical Arguments
Argument from the impossibility of an actually infinite number of things. An
actually infinite number of things cannot exist, because this would involve all sorts
of absurdities, which I shall illustrate in a moment. And if the universe never had a
beginning, then the series of all past events is actually infinite. That is to say, an
actually infinite number of past events exists. Because an actually infinite number
of things cannot exist, then an actually infinite number of past events cannot exist.
The number of past events is finite, therefore the series of past events had a
beginning. Since the history of the universe is identical to the series of all past
events, the universe must have begun to exist. This argument can also be
formulated in three steps:
- An actually infinite number of things cannot exist.
- A beginningless series of events in time entails an actually infinite number of
things.
- Therefore, a beginningless series of events in time cannot exist.
Let us examine each step together.
An actually infinite number of things cannot exist. In order to understand this first
step, we need to understand what an actual infinite is. There is a difference
between a potential infinite and an actual infinite. A potential infinite is a collection
that is increasing toward infinity as a limit but never gets there. Such a collection is
really indefinite, not infinite. An actual infinite is a collection in which the number of
members really is infinite. The collection is not growing toward infinity; it is infinite,
it is “complete.” This sort of infinity is used in set theory to designate sets that
have an infinite number of members, such as {1,2,3...}. Now I am arguing, not
that a potentially infinite number of things cannot exist, but that an actually infinite
number of things cannot exist. For if an actually infinite number of things could
exist, this would spawn all sorts of absurdities.
Perhaps the best way to bring this home is by means of an illustration. Let me use
on of my favorites, Hilbert’s Hotel, a product of the mind of the great German
mathematician David Hilbert. 5 Let us imagine a hotel with a finite number of
rooms. Suppose, furthermore, that all the rooms are full. When a new guest
arrives asking for a room, the proprietor apologizes, “Sorry, all the rooms are full.”
But now let us imagine a hotel with an infinite number of rooms and suppose once
more that all the rooms are full. There is not a single vacant room throughout the
entire infinite hotel. Now suppose a new guest shows up, asking for a room. “But
of course!” says the proprietor, and he immediately shifts the person in room #1
into room #2, the person in room #2 into room #3, the person in room #3 into
room #4, and so on, out to infinity. As a result of these room changes, room #1
now becomes vacant and the new guest gratefully checks in. But remember,
before he arrived, all the rooms were full! Equally curious, according to the
mathematicians, there are now no more persons in the hotel than there were
before: the number is just infinite. But how can this be? The proprietor just added
the new guest’s name to the register and gave him his keys–how can there not be
one more person in the hotel than before? But the situation becomes even
stranger. For suppose an infinity of new guests show up at the desk, asking for a
room. “Of course, of course!” says the proprietor, and he proceeds to shift the
person in room #1 into room #2, the person in room #2 into room #4, the
person in room #3 into room #6, and so on out to infinity, always putting each
former occupant into the room number twice his own. As a result, all the odd
numbered rooms become vacant, and the infinity of new guests is easily
accommodated. And yet, before they came, all the rooms were full! And again,
strangely enough, the number of guests in the hotel is the same after the infinity of
new guests check in as before, even though there were as many new guests as
old guests. In fact, the proprietor could repeat this process infinitely many times
and yet there would never be one single person more in the hotel than before.
But Hilbert’s Hotel is even stranger than the German mathematician made it out to
be. For suppose some of the guests start to check out. Suppose the guest in
room #1 departs. Is there not now one less person in the hotel? Not according to
the mathematicians–but just ask the woman who makes the beds! Suppose the
guests in rooms ##1,3,5,... In this case an infinite number of people have left the
hotel, but according to the mathematicians there are no less people in the
hotel–but don’t talk to that laundry woman! In fact, we could have every other
guest check out of the hotel and repeat this process infinitely many times, and yet
there would never be any less people in the hotel. But suppose that the persons in
rooms ##4,5,6,...checked out. At a single stroke the hotel would be virtually
emptied, the guest register would be reduced to three names, and the infinite
would be converted to finitude. And yet it would remain true that the same
number of guests checked out this time as when the guests in rooms
##1,3,5...checked out. Can anyone believe that such a hotel could exist in reality?
Hilbert’s Hotel is absurd. As one person remarked, if Hilbert’s Hotel could exist, it
would have to have a sign posted outside: NO VACANCY–GUESTS WELCOME. The
above sorts of absurdities show that it is impossible for an actually infinite number
of things to exist. There is simply no way to avoid these absurdities once we admit
the possibility of the existence of an actual infinite. William J. Wainwright had
suggested that we could reduce the force of these paradoxes by translating them
into mathematical terms; for example, an actually infinite set has a proper subset
with the same cardinal number as the set itself. 6 But this amounts only to a way
of concealing the paradoxes; it was to bring out the paradoxical character of these
mathematical concepts that Hilbert came up with his illustration in the first place.
And the whole purpose of philosophical analysis is to bring out what is entailed by
unanalyzed notions and not to leave them at face value.
But does the possibility of an actual infinite really entail that such absurdities are
possible, or could an actual infinite be possible, as Wainwright suggests, without
thereby implying that such absurdities are possible? The answer to that question is
simple: the possibility of the existence of an actual infinite entails, that is,
necessarily implies, that such absurdities could exist. Hilbert’s illustration merely
serves to bring out in a practical and vivid way what the mathematics necessarily
implies; for if an actual infinite number of things is possible, then a hotel with an
actually infinite number of rooms is impossible, then so is the real existence of an
actual infinite.
These considerations also show how superficial Mackie’s analysis of this point is.7
He thinks that th |