Summa Theologica
1.II.3
Article 3. 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.
Objection 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." (Exodus 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 to Objection 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 to Objection 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.
 Back to the Feast of St. Thomas Aquinas
Back to Seasonal Customs
Back to Being Catholic
Index
|
