In this book Summa Theologica., Aquinas
puts forward five ways to the existence of
God. The first three of his ways make up
the popular version of the Cosmological
Argument.
Aquinas believed that “proofs” for the
existence of God are needed because the
existence of God is not self-evident – it is
not obvious that God exists and it is quite
easy to think of the world existing without
God.
 Everything that moves is moved by something else;
 That mover must also be moved by something else;
 But you cannot have an infinite chain of movers, or there would
be no reason for movement to get started at all;
 Therefore, there must be an unmoved mover, producing
movement in everything, without itself being moved;
 This unmoved mover is what people understand to be God.
Potential
Actual
Wood is potentially hot.
Fire is actually hot
Change
Fire makes the potentially
hot wood actually hot.
 Everything has a cause;
 Every cause has its own cause;
 You can not have an infinite number of causes;
 Therefore there must be an uncaused cause, which causes
everything to happen without itself being caused by anything
else;
 Such an uncaused cause is what people understand by “God.”
First efficient
cause
Intermediate
cause
Ultimate
cause
 Ordinary things start to exist and later stop existing (they are finite
or contingent)
 Therefore at some time none of them was in existence;
 But something only comes into existence by being caused by
something else that already exists;
 Therefore there must be a being whose existence is necessary and
therefore not limited by time. This being is what people understand by
God.
Copleston states that the existence of
contingent things can only be explained if we
accept that there is a being with necessary
existence who started off the chain of all
other existent things. There must, Copleston
argues, be a sufficient explanation for the
existence of all contingent things and this
must be God, who contains within himself the
reason for his existence.
“...in order to explain existence, we must
come to a being which contains within
itself the reason for its own existence,
that is to say, that which cannot not
exist.”
“If you suppose the
world eternal, you will
suppose nothing but a
succession of states
and will not find in any
of them a sufficient
reason.”
Leibniz believed that the existence of the universe
requires a sufficient reason.
•Everything that begins to exist has a cause for its existence;
•The universe began to exist;
•Therefore the universe must have a cause.
Rejection of Infinite Regression:
•An actual infinite number can not exist;
•Therefore, the series of causes for the world being as
it is now cannot be an infinite temporal (worldly)
sequence;
•So, the sequences of causes in the world can not be
infinite;
•Therefore, the world began to exist at some point in
the past.
•There was a time in the past when one of two states
was possible – that there should be, or should not be, a
universe.
God is connected to the world as the first
mover, first cause, and the One with
necessary existence who begins the lives of
all those whose existence is contingent.
The God of Aquinas’ Cosmological Argument is one who
is linked to a world which is ontologically dependent on
Him. If God, as the necessary being, stops His creative
action, then the world will no longer exist. As God begins
the chain of motion and the chain of cause and effect,
God can also stop them by withdrawing from the world.
Bede Rundle states that the question
‘why is there something rather than
nothing?’ is “Philosophy’s central and
most perplexing problem.”
“Nothing can come of nothing.”
Perhaps this argument cannot lead to faith in God, but maybe it
doesn’t try to do this; “I am not seeking to understand in order to
believe, but believe in order that I may understand.” (Anselm)
Aquinas intended the argument to point people
towards a belief in God and to suggest that
there is evidence for religious faith. It is
possible that the Cosmological Argument could
bring someone to belief in God or strengthen a
religious person’s faith.
However, Aquinas himself referred to his ideas of
‘ways’ not ‘proofs’ and so it seems unlikely that an
atheist would begin to have religious faith after
reading about the Cosmological Argument. As the
argument is inductive, the conclusions are not
conclusive. Swinburne asserted that the argument
makes it very likely that God does exist, but it is
doubtful that anyone except a religious believer
would be convinced by the argument. There are
many flaws in the argument, which have been
pointed out in this booklet that could be used by a
disbeliever to discredit the argument and maintain
their atheistic standpoint.
Anselm stated that the argument for God existence are
there to enable believers to understand more about their
existing faith, rather than bringing atheists to belief in God.
We have also seen that the argument points to a necessary
being and first mover / cause rather than the God of
classical theism. Perhaps thinkers who support the
argument can, at best, expect agnostics to lean towards
the idea that there might be a ‘sufficient reason’ for the
existence of the universe.
They can not expect them to be led to the all-powerful,
all-loving God of Christianity, as the sufficient reason
could be an evil God, or many gods.
Therefore, this argument might serve to strengthen
existing religious faith and might give believers an
argument to justify their belief in God. However, it is
unlikely that a person who is not a believer will be drawn to
faith in the Christian God by the Cosmological Argument.