Whether God Exists?
Objection 1: It seems that God does not exist; because if one of two
contraries be infinite, the other would be altogether destroyed. But
the word "God" means that He is infinite goodness. If, therefore, God
existed, there would be no evil discoverable; but there is evil in the
world. Therefore God does not exist.
Obj. 2: Further, it is superfluous to suppose that what can be
accounted for by a few principles has been produced by many. But it
seems that everything we see in the world can be accounted for by
other principles, supposing God did not exist. For all natural things
can be reduced to one principle which is nature; and all voluntary
things can be reduced to one principle which is human reason, or will.
Therefore there is no need to suppose God's existence.
_On the contrary,_ It is said in the person of God: "I am Who am." (Ex.
3:14)
_I answer that,_ The existence of God can be proved in five ways.
The first and more manifest way is the argument from motion. It is
certain, and evident to our senses, that in the world some things are
in motion. Now whatever is in motion is put in motion by another, for
nothing can be in motion except it is in potentiality to that towards
which it is in motion; whereas a thing moves inasmuch as it is in act.
For motion is nothing else than the reduction of something from
potentiality to actuality. But nothing can be reduced from
potentiality to actuality, except by something in a state of
actuality. Thus that which is actually hot, as fire, makes wood, which
is potentially hot, to be actually hot, and thereby moves and changes
it. Now it is not possible that the same thing should be at once in
actuality and potentiality in the same respect, but only in different
respects. For what is actually hot cannot simultaneously be
potentially hot; but it is simultaneously potentially cold. It is
therefore impossible that in the same respect and in the same way a
thing should be both mover and moved, i.e. that it should move itself.
Therefore, whatever is in motion must be put in motion by another. If
that by which it is put in motion be itself put in motion, then this
also must needs be put in motion by another, and that by another
again. But this cannot go on to infinity, because then there would be
no first mover, and, consequently, no other mover; seeing that
subsequent movers move only inasmuch as they are put in motion by the
first mover; as the staff moves only because it is put in motion by
the hand. Therefore it is necessary to arrive at a first mover, put in
motion by no other; and this everyone understands to be God.
The second way is from the nature of the efficient cause. In the world
of sense we find there is an order of efficient causes. There is no
case known (neither is it, indeed, possible) in which a thing is found
to be the efficient cause of itself; for so it would be prior to
itself, which is impossible. Now in efficient causes it is not
possible to go on to infinity, because in all efficient causes
following in order, the first is the cause of the intermediate cause,
and the intermediate is the cause of the ultimate cause, whether the
intermediate cause be several, or only one. Now to take away the cause
is to take away the effect. Therefore, if there be no first cause
among efficient causes, there will be no ultimate, nor any
intermediate cause. But if in efficient causes it is possible to go on
to infinity, there will be no first efficient cause, neither will
there be an ultimate effect, nor any intermediate efficient causes;
all of which is plainly false. Therefore it is necessary to admit a
first efficient cause, to which everyone gives the name of God.
The third way is taken from possibility and necessity, and runs thus.
We find in nature things that are possible to be and not to be, since
they are found to be generated, and to corrupt, and consequently, they
are possible to be and not to be. But it is impossible for these
always to exist, for that which is possible not to be at some time is
not. Therefore, if everything is possible not to be, then at one time
there could have been nothing in existence. Now if this were true,
even now there would be nothing in existence, because that which does
not exist only begins to exist by something already existing.
Therefore, if at one time nothing was in existence, it would have been
impossible for anything to have begun to exist; and thus even now
nothing would be in existence--which is absurd. Therefore, not all
beings are merely possible, but there must exist something the
existence of which is necessary. But every necessary thing either has
its necessity caused by another, or not. Now it is impossible to go on
to infinity in necessary things which have their necessity caused by
another, as has been already proved in regard to efficient causes.
Therefore we cannot but postulate the existence of some being having
of itself its own necessity, and not receiving it from another, but
rather causing in others their necessity. This all men speak of as
God.
The fourth way is taken from the gradation to be found in things.
Among beings there are some more and some less good, true, noble and
the like. But _more_ and _less_ are predicated of different things,
according as they resemble in their different ways something which is
the maximum, as a thing is said to be hotter according as it more
nearly resembles that which is hottest; so that there is something
which is truest, something best, something noblest and, consequently,
something which is uttermost being; for those things that are greatest
in truth are greatest in being, as it is written in _Metaph._ ii. Now
the maximum in any genus is the cause of all in that genus; as fire,
which is the maximum heat, is the cause of all hot things. Therefore
there must also be something which is to all beings the cause of their
being, goodness, and every other perfection; and this we call God.
The fifth way is taken from the governance of the world. We see that
things which lack intelligence, such as natural bodies, act for an
end, and this is evident from their acting always, or nearly always,
in the same way, so as to obtain the best result. Hence it is plain
that not fortuitously, but designedly, do they achieve their end. Now
whatever lacks intelligence cannot move towards an end, unless it be
directed by some being endowed with knowledge and intelligence; as the
arrow is shot to its mark by the archer. Therefore some intelligent
being exists by whom all natural things are directed to their end; and
this being we call God.
Reply Obj. 1: As Augustine says (Enchiridion xi): "Since God
is the highest good, He would not allow any evil to exist in His
works, unless His omnipotence and goodness were such as to bring good
even out of evil." This is part of the infinite goodness of God, that
He should allow evil to exist, and out of it produce good.
Reply Obj. 2: Since nature works for a determinate end under
the direction of a higher agent, whatever is done by nature must needs
be traced back to God, as to its first cause. So also whatever is done
voluntarily must also be traced back to some higher cause other than
human reason or will, since these can change or fail; for all things
that are changeable and capable of defect must be traced back to an
immovable and self-necessary first principle, as was shown in the body
of the Article.
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