THOMAS AQUINAS: SUMMA THEOLOGIAE
Thomas Aquinas is perhaps the greatest and certainly the most famous
example of that intellectual movement which we call medieval scholasticism. "
Born into a noble Italian family in 1224 or 1225, Thomas was earmarked by his
parents to pursue a respectable ecclesiastical career as abbot of the Benedictine
monastery at Monte Cassino, thus improving both The family fortunes and his
Thomas had other ideas. In 1244 he joined the Dominican order. Like The
Franciscans, the Dominicans were a mendicant order. Their original function was
The control of heresy through preaching. (Hence their real name - Ordo
praedicatorum or "order of Preachers" - the more popular label "Dominicans"
being derived from the name of Their founder, St. Dominic.) By the middle of
The Thirteenth century They were gaining a reputation for learning and piety,
but neither of these qualities was precisely what the noble house of Aquino had in
mind when they thought of Thomas' future.
Their response to Thomas' decision was swift and direct. They kidnapped
him back from the Dominicans and held him captive for about a year, meanwhile
plying him with various temptations including a naked woman. Thomas
persevered, however, and They finally acquiesced. Shortly thereafter, the
Dominicans sent their newly-recovered recruit off to Paris.
Paris was an exciting place to be in 1245. Scholars were rediscovering
Aristotle, asking if and how his philosophy could be reconciled with Christian
revelation. Thomas was destined to produce one great answer to that question.
Thomas' most significant work is his Summa theologiae or 'summary of
Theology,' a gigantic work which attempts to present all of Christian theology as
systematically as possible. Thomas worked on it from 1266 through 1273. Then,
when he was nearly finished, he underwent an experience so intense that, as he
himself explained, everything he had written seemed like straw. He completely
stopped writing and died three months later. Thomas was canonized in 1323.
The Summa theologiae is written in a form common to treatises of that
age. All of theology is divided into its major topics. These, in turn, are divided
into subtopics described by Thomas as 'questions. " The first "question" in the
Summa theologiae deals with The nature of Theology itself, the second with
The 'questions" are in turn divided into what Thomas calls "articles," specific
queries concerning the topic being explored in that particular "question." (Thus,
confusingly enough, what Thomas calls "questions" are actually general topics,
whereas what he calls "articles" are really what we would mean by the word
"questions.") These "articles" form the basic unit of the Summa theologiae, and
they proceed according to an invariable form. A specific query is made, then a
section beginning with the word videtur ("it seems that") offers arguments for
what will later turn out to be the wrong answer to that query. Next, a brief
section be ginning with the words sed contra ("but on the contrary") introduces a
different answer. A section labeled responsio ("response") finally presents
arguments for what Thomas considers the correct view. The question then closes
with a refutation of the arguments presented in the videtur section.
The following selection consists of the prologue and first two questions of
the Summa theologiae. Some articles of the first question are omitted, but those
included are given in their entirety, so that the reader can see how the work (and
Thomas' mind) is constructed.
Since a teacher of catholic truth should instruct not only the advanced
but beginners as well - as St. Paul says, "Like babes in Christ I fed you milk and
not meat" (I Cor. 3:1) - our intention in this work is to convey the content of the
Christian religion in a way fit for the training of beginners. We have seen that
novices in this study are greatly hindered by the various writings on the subject.
They are hindered partly because of the multiplication of useless questions,
articles and arguments in these writings; partly because the order in which
essential material is delivered in these writings is determined, not by the nature of
doctrine itself, but by the books on which the writings are commenting; and
partly because frequent repetition has bred boredom and confusion in the minds
Eager to avoid these and other pitfalls we shall now attempt to examine the
content of sacred doctrine briefly and clearly, so far as the material allows,
twisting in God's aid.
Question 1: Sacred doctrine, what it is and what it includes.
In order to contain our investigation within limits, we must first
investigate sacred doctrine itself, asking what it is and how far it extends. Ten
questions must be asked.
1. Whether it is necessary
2. Whether it is a science
3. Whether it is one or many
4. Whether it is speculative or practical
5. How it compares with other sciences
6. Whether it is wisdom
7. What is its subject
8. Whether it is argumentative
9. Whether it should use metaphorical or symbolic language
10. Whether the sacred scripture containing this doctrine is to be
interpreted according to several senses.
Article 1: Whether it is necessary to have another doctrine besides the
Let us proceed to the first point. It seems that there is no necessity for
any doctrine beyond the philosophical disciplines. Man should not strive after that
which is beyond his reason. As Ecclesiastics says, "Do not be curious about what
is above you" (Ecclus. 3:22). The things which can be investigated by reason are
sufficiently covered in the philosophical disciplines, however. Thus it seems
superfluous to have some doctrine beyond the philosophical disciplines.
Furthermore, any doctrine can deal only with that which is; for nothing can be
known except that which is true, and that which is true is identical with that
which is. Yet everything other signification, through which the things signified
by the words signify something else in turn, is called the spiritual sense. It is
based on the literal sense and presupposes it.
But on the contrary Paul says, "All divinely-inspired scripture is useful for
teaching, arguing, correcting and instructing in justice" (II Tim. 3:16). Divinely-
inspired scripture does not pertain to philosophical disciplines, however, for they
are discovered by human reason. Thus it is useful to have another, divinely-
inspired doctrine besides the philosophical disciplines.
Response: It must be said that, besides the philosophical disciplines which
are investigated by human reason, another doctrine based on revelation was
necessary for human well-being. Such is true, in the first place, because man is
ordered by God to a certain end which exceeds the grasp of reason. As Isaiah
says, "Eye has not seen, God, without you, what you have prepared for those who
love you" (lsa. 64:4). The end must be fore known to man, however, since he
must order his intentions and actions to that end. Thus it was necessary to human
well-being that certain things exceeding human reason be made known to man
through divine revelation.
Even in the case of those things which can be investigated by human
reason, it was necessary for man to be instructed by divine revelation. The truth
concerning God, if left to human reason alone, would have appeared only to a
few, and only after a long search, and even then mixed with many errors; yet all
of man's well-being, which is in God, depends on knowledge of this truth. Thus,
in order that this well-being should become known to men more commonly and
more securely, it was necessary that they be instructed by divine revelation.
Thus it was necessary that, besides the philosophical doctrines which can be
investigated by reason, there be a sacred doctrine known through revelation.
To the first argument, therefore, it must be said that, although what is
above human knowledge should not be investigated by reason, once revealed by
God it should be accepted through faith. Thus it is added in the same chapter of
Ecclesiasticus, "Many things above human understanding are shown to you"
(Ecclus. 3:25). Sacred doctrine consists of these things.
To the second argument it must be said that there are diverse sciences
because things can be known in various ways. For example, the astronomer and
the natural philosopher both demonstrate the same conclusion, such as that the
world is round; yet the astronomer does so through mathematics, while the
natural philosopher does so in a way that takes matter into account. Thus there is
no reason why those things treated by the philosophical disciplines through
natural reason should not also be treated by another science insofar as they are
known by the light of divine revelation. Thus the theology which pertains to
sacred doctrine differs from that theology which is a part of philosophy.
* * * * * * * *
Article 5: Whether sacred doctrine is worthier than the other sciences.
Let us proceed to the fifth point. It seems that sacred doctrine is not worthier
than other sciences. Certitude contributes to the worth of a science; yet other
sciences, the premises of which cannot be doubted, seem to be more certain than
sacred doctrine, the principles of which (that is, the articles of faith) are open to
Furthermore, it is characteristic of a lower science to draw on a higher
one, just as music draws on arithmetic. Sacred doctrine draws from the
philosophical disciplines, for Jerome says that "the ancient teachers so filled their
books with the doctrines and opinions of philosophers that you do not know
which to marvel at first, their worldly erudition or their knowledge of the
scriptures." Thus sacred doctrine is inferior to other sciences.
But on the contrary, other sciences are called the maidservants of this one.
Proverbs says, "She has sent her servants to invite to the tower (Prov. 9:3).
Response: It must be said that, since this science is practical in one respect
and speculative in another, it transcends all other sciences, both speculative and
practical. Among the speculative sciences, one is said to be worthier than another
either because of its certainty or because of the worth of its subject. This science
exceeds all others on both counts. It does so in regard to certainty because other
sciences gain their certainty through the light of natural reason, which can err,
whereas this one gains its certainty through the light of divine wisdom, which
cannot be deceived. It does so in regard to the dignity of its matter because this
science deals principally with things which transcend reason, being above it,
whereas other sciences consider only those things which are subject to reason.
Among the practical sciences, one is said to be worthier if it is ordered to a
higher end. Thus the study of politics is worthier than that of warfare because the
good of an army is ordered to the good of the city it serves. The end of this
science insofar as it is practical is eternal bliss, to which all other practical
sciences are ordered as the ultimate end. Thus it is evident that this science is
worthier than all others in every way.
To the first argument, therefore, it must be said that there is nothing to
prevent that which is more certain in itself from being less certain to us because
of the weakness of our intellects, which, as Aristotle says, "are related to the most
evident things as the eyes of a bat are to the sun." Thus the doubt some people
experience regarding articles of the faith is not due to their uncertainty, but to the
weakness of the human mind. Nevertheless, as Aristotle observes, the smallest
inkling of the highest matters is more desirable than certain knowledge of the
least important matters.
To the second argument it must be said that this science can borrow
something from the philosophical disciplines, not because it needs to do so, but in
order to clarify its content. For it accepts its principles, not from other sciences,
but immediately from God through revelation. Thus it does not receive from
other sciences as from superiors, but rather uses them as inferiors and servants,
just as an architect uses workers or a statesman uses soldiers. Moreover, its use of
other sciences is due, not to any defect or insufficiency within itself, but to a
defect in our intellect, which are more easily led to the things above reason set
forth in this science if they travel by way of those things known through natural
reason, which is the source of other sciences.
* * * * * * * *
Article 8: Whether one can defend this doctrine through argument.
Thus we proceed to the eighth point. It seems that this doctrine cannot be
defended through argument, for Ambrose says, "Away with argument where
faith is sought!" Faith, however, is primarily sought in this doctrine, for as John
says, "These things are written in order that you may believe" (Jn. 20:30). Thus
sacred doctrine cannot be defended through argument.
But on the contrary, Paul says that a bishop should "embrace the faithful
word according to sound doctrine, so that he will be able to exhort in sound
doctrine and argue with those who deny it" (Titus 1:9).
Response: It must be said that other sciences do not argue to prove their
premises, but rather argue from these premises to establish other times within the
particular science. Thus this doctrine does not argue to prove its premises, which
are the articles of faith, but proceeds from them to establish other things, just as
the apostle Paul argues from the resurrection of Christ to prove a general
resurrection (I Cor. 15:12).
It must be born in mind, then, that within the philosophical sciences the
inferior sciences neither prove their principles nor dispute with those who deny
them. They leave that task to a superior science. The supreme philosophical
science, metaphysics, can dispute against someone who denies its premises only if
the adversary will concede something. If he concedes nothing, then debate is
impossible, although it may still be possible to show that the adversary's
argument is invalid.
Thus sacred scripture, having no superior, can debate with one who denies
its premises only if the adversary concedes some part of divine revelation. In this
way we debate with heretics on the basis of sacred doctrine, using one article
which they accept to support another which they deny. If the adversary believes
nothing of what is revealed in sacred doctrine, then there is no way left to prove
the articles of faith through reason. It is still possible to refute arguments
advanced against the faith, however. Since the faith rests upon infallible truth and
it is impossible to prove what is contrary to truth, it is clear that arguments
against the faith are not really proofs and can be refuted.
To the first argument, therefore, it must be said that the arguments of
human reason cannot prove the faith, but one can argue from articles of faith to
other conclusions, as was said above.
To the second, it must be said that argument from authority is very
appropriate to this doctrine, since its premises are derived from revelation. Thus
one must believe in the authority of those to whom the revelation was given. Nor
does this fact derogate from the worth of this doctrine, for an argument from
authority may be the weakest kind when it is based on human revelation, but it is
the strongest kind when based on divine revelation.
Nevertheless, sacred doctrine also uses human reason. It does so not to
prove the faith - for that would detract from the merit of faith - but to clarify
some of its implications. Therefore, since grace protects nature rather than
erasing it, natural reason should serve faith just as the natural inclination of the
will obeys love. The apostle Paul speaks of "bringing every understanding into
captivity in the service of Christ" (II Cor. 10:5). Thus sacred doctrine appeals to
the authority of philosophers in those areas where they were able to arrive at the
truth through natural reason, just as Paul employs a passage from Aratus, saying,
"As some of your poets have said, we are the offspring of God" (Acts 17:28).
Nevertheless, sacred doctrine employs such authorities only insofar as they
can provide extraneous arguments, the proofs of which are probable rather than
certain. It appeals to the authority of canonical scripture as an authority proper to
itself, that of the teachers of the church, but here again the arguments are merely
probable. For our faith rests on the revelation made to the apostles and prophets
who wrote the canonical books, and not on any revelation (if such there was)
made to teachers. Thus Augustine says in his letter to Jerome, "Only to those
books of the scripture called 'canonical' have I learned to pay such honor that I
believe no author to have erred in writing them. Other writers I read in such a
way that, whatever holiness and learning they display, I do not consider what they
say to be true simply because they say it."
Article 9: Whether holy scripture should use metaphorical or symbolic language.
Thus we proceed to the ninth point. It seems that holy scripture should not
use metaphors. That which is proper to a lower type of learning does not seem
fitting for this science, which, as has been said, holds the highest place. It is
proper to poetry, the lowest type of learning, to proceed through various
similitudes and representations, however. Thus the use of such similitudes is not
fitting for this science.
Furthermore, it seems that the purpose of this doctrine is to make the truth
appear plainly, and there is a reward promised to those who do so. Ecclesiasticus
says, "Those who explain me shall have eternal life" (Ecclus. 24:31). The truth is
hidden through similitudes, however. Thus it is unfitting for this doctrine to
convey divine matters through similitudes taken from the corporeal world.
Furthermore, the more sublime creatures are, the more similar they are to
God. If, then, some properties of created beings are used in speaking of God,
then they should be taken from higher rather than lower creatures. This is,
however, frequently the case in scripture.
But on the contrary, in Hosea God says, "I have multiplied visions in them
and I have used similitudes by the ministry of the prophets" (Hos. 12:10). To
communicate something by similitude is to speak metaphorically. Thus sacred
doctrine employs metaphors.
Response: It must be said that the communication of divine and spiritual
things through corporeal similitudes is quite fitting for holy scripture. God
provides for all things according to their natures. It is natural for man to attain
knowledge through the use of sensible things, for all of our knowledge begins
with sense experience. Thus in sacred scripture spiritual matters are quite
properly conveyed to us through metaphors taken from the corporeal world.
That is what Dionysius means when he says, "The divine rays cannot illuminate us
unless they are wrapped in many sacred veils.
The presentation of spiritual matters through corporeal similitudes is also
fitting because holy scripture is addressed to all of us in common. As Paul says,
"I am a debtor to the wise and to the foolish" (Rom. 1:14). Scripture discusses
spiritual matters in the form of physical likenesses so that they can be understood
by the uneducated, who are incapable of understanding them in themselves.
To the first argument, therefore, it must be said that poetry uses metaphors
for the sake of representation, for representation is naturally delightful to man.
Sacred doctrine, however, uses metaphors because they are necessary and useful,
as has been said.
To the second it must be said that the ray of divine revelation is not
destroyed by the sensible figures veiling it, but, as Dionysius says, it remains in
its truth in order that the minds receiving the revelation should not be permitted
to stay on the level of the similitudes but should be raised to an understanding of
the ideas behind them, and so that others should be instructed by those to whom
the revelation is made. To this end the things conveyed through metaphor in one
part of scripture are more directly explained in other parts.
Moreover, veiling the message in metaphor has certain advantages. It is
good training for scholars and guards the faith against ridicule by infidels, of
whom Christ speaks when he says, "Do not throw that which is holy to the dogs"
In reply to the third, it must be said that, as Dionysius teaches, divine
things are more fittingly conveyed in scripture by the images of vile bodies than
by images of noble bodies. There are three reasons why this is so. First, it guards
us against error, since there can be no doubt that such images are not literally
true. If divine things were described in terms of noble bodies, such a mistake
might be made, particularly by those who can things of nothing nobler than a
body. Second, because this practice is more appropriate to the knowledge of God
attained in this life, when we see what God is not more clearly than what he is.
Thus similitudes taken from things furthest removed from God give us a truer
picture of him in the sense that they convey how far above our word or thought
he really is. Third, because in this way divine things are more effectively hidden
from the unworthy.
Article 10: Whether the same passage of holy scripture can have several senses.
Thus we proceed to the tenth point. It seems that the same passage of holy
scripture cannot have several senses, namely the historical or literal, the
allegorical, the tropological or moral, and the anagogical. Multiple senses in
scripture prepare the way for confusion and deception. They also compromise
coherent reasoning. From several propositions there results, not an argument, but
a collection of fallacies. Sacred scripture, however, should display the truth
without any fallacy whatsoever. Thus there should not be several senses in the
Furthermore, Augustine says, "The scripture which is called 'The Old
Testament' has a fourfold meaning, namely history, etiology, analogy and
allegory." These four seem inconsistent with the aforementioned. Thus it does not
seem fitting that the same passage of sacred scripture should be exposited
according to the four aforementioned senses.
Furthermore, there is also a parabolic sense, which does not seem to be
included among these four senses.
But on the contrary Gregory says, "Sacred scripture transcends all other
sciences in the manner of its expression, because in one and the same statement,
while narrating an event, it proclaims a mystery."
Response: It must be said that the author of sacred scripture is God, who
has the power not only to use words in expressing himself - men can do that
much - but of using things as well. Thus, since words signify something in any
science, this science is special in that not only the words but the things signified
by the words signify something. The primary signification, through which words
signify things, is called the literal or historical sense. That signification whereby
things signified by words have themselves also a signification is called
the spiritual sense, which is based on the literal, and presupposes it.
Now this spiritual sense has a threefold division.
[This phrase in italics was
missing in the base file for this texts, and has been supplied from the
Dominican Fathers' translation.]
This spiritual sense is itself divided in a threefold way. Paul says, "The Old
Law is a figure of the New Law" (Heb. 7:19), and the New Law is, as Dionysius
says, "a figure of the glory to come." Moreover, in the New Law the things that
are done are signs of what we ourselves should do.
Thus, insofar as things in the Old Law signify things in the New Law, we
have the allegorical sense. Insofar as things done by Christ or by those who
prefigure Christ are signs of what we ourselves should do, we have the moral
sense. Insofar as they signify what is involved in eternal glory, we have the
Because the literal sense is what the author intends, and because the author
of sacred scripture is God who contains all things within his understanding, there
is nothing impossible about even the literal sense containing several meanings, as
To the first argument, therefore, it must be said that manifold senses do
not lead to equivocation or to any other type of ambiguity, for, as was just said,
theses senses are not multiplied in such a way that a single word signifies several
things, but rather because the things signified by these words can be signs of still
other things. Thus no confusion follows from the reading of sacred scripture, for
all other senses are founded on the literal sense. From it alone arguments can be
drawn, and not from what is said allegorically, as Augustine explains in his letter
against Vincent the Donatist. Nor does this fact detract in any way from sacred
scripture, for nothing necessary to the faith is said in a spiritual sense which is
not explicitly stated in the literal sense elsewhere.
To the second argument it must be said that these three things - history,
etiology and analogy - belong to a single literal sense. It is history when, as
Augustine explains, something is straightforwardly reported. It is etiology when
the cause of that thing is explained, as when God explains why Moses permitted
the repudiation of wives, namely because of the hardness of their hearts. It is
analogy when the truth of one scripture is shown to be consistent with the truth of
another. Among the four, allegory alone stands for the spiritual senses. In the
same way, Hugh of St. Victor includes the anagogical sense under the allegorical
and enumerates only three senses: The historical, allegorical and tropological.
To the third it must be said that the parabolic sense is included under the
literal, for words can signify something properly and something else figuratively.
In the latter case, the literal sense is not the figure of speech itself but the thing
figured by it. For example, when scripture refers to the arm of God, the literal
sense is not that God has a physical limb, but that he has what that limb signifies,
namely the power to do things. Thus it is clear that no falsehood can ever
underlie the literal sense of sacred scripture.
Question 2: Concerning God, whether God exists
As to this question, there are three points of inquiry:
1. Whether God's existence is self-evident
2. Whether it can be demonstrated
3. Whether God exists.
Article 1: Whether God's existence is self-evident.
Thus we proceed to the first point. It seems that God's existence is
self-evident, for those things are said by us to be self-evident the knowledge of
which is naturally within us, as is the case with first principles. But, as John of
Damascus says, "The knowledge of God's existence is naturally implanted in all
things." Therefore God's existence is self-evident.
Furthermore, those things are said to be self-evident the truth of which is
obvious once the meaning of the words is clear. For example, when we
understand the means of the words "whole" and "part," we immediately realize
that every whole is greater than its part. Once we understand the meaning of the
word "God," however, it immediately follows that God exists. The words itself
signifies "that being a greater than which cannot be signified." That which exists
in fact and in the mind is greater than that which exists in the mind alone. Thus,
since the moment we understand the meaning of the word "God" he exists in our
minds, it follows that he must also exist in fact. Thus God's existence is self-
Furthermore, it is self-evident that truth exists, for whoever denies the
existence of truth simultaneously concedes its existence. If truth does not exist,
then it is true that truth does not exist; yet if something is true, then truth exists.
God, however, is truth itself. "I am the way, the truth and the life" (Jn. 14:6).
Therefore God's existence is self-evident.
But on the contrary, no one can think the opposite of what is self-evident,
as Aristotle remarks. One can, however, think the opposite of the proposition
"God exists," for, as the Psalm says, "The fool says in his heart, 'there is no
God." (Ps. 13:1, 52:1). Thus it is not self-evident that God exists.
Response: It must be said that a thing can be called "self-evident" in two-
ways, in itself and in relation to us. A proposition is self-evident when its
predicate is included in the definition of its subject. For example, in the
proposition "man is an animal," the idea of "animal" is included in the definition
of "man." Thus if everyone knows the definitions of both subject and predicate,
the proposition will be self-evident to all, as is the case with the first principles of
demonstration, the terms of which are so common that no one is ignorant of
them, such as "being" and "nonbeing," "whole" and "part," etc. If, the proposition
may be self-evident in itself, but not to them. Thus it happens, as Boethius says,
that some things are common conceptions of the mind" and are self-evident
"among the learned only, such as that incorporeal beings do not occupy a place."
I say, therefore, that this proposition, "God exists," is self-evident in itself,
since the predicate is the same as the subject. For God is his own existence, as will
be seen later. Nevertheless, because we do not know what is involved in being
God, the proposition is not self-evident to us, but needs to be demonstrated
through those things that are more evident to us though less evident to
themselves, namely God's effects.
To the first argument, therefore, it must be said that a general and
confused knowledge of God's existence is naturally infused within us, for God is
man's beatitude and man naturally desires beatitude. What man naturally desires
he naturally knows. This is not to know God's existence specifically, however. It
is one thing to know that someone is approaching and quite another to know that
Peter is approaching, even though that someone may actually be Peter. Many
people think that the perfect good of man called "beatitude" is wealth, some
imagine it to be pleasure, and so on.
To the second argument it must be said that he who hears the name "God"
may perhaps not know that it signifies "something greater than which cannot be
conceived," since some people have thought of God as a body. Granting,
however, that someone should think of God in this way, namely as "that being a
greater than which cannot be conceived, "it does not follow on this account that
the person must understand what is signified to exist in the world of fact, but only
in the mind. Nor can one argue that it exists in fact unless one grants that there
actually exists in fact something a greater than which cannot be conceived. It is,
however, precisely this assertion the atheist denies.
To the third, it must be said that the existence of truth in general is self-
evident to us, but it is not self-evident that this particular being is the primal
Article 2: Whether God's existence is demonstrable.
We proceed thus to the second point. It seems that God's existence is
not demonstrable, for it is an article of faith. What is a matter of faith cannot be
demonstrable, for demonstration allows one to know, whereas faith, as Paul says,
is in "things not seen" (Heb. 11:1). Therefore God's existence is not
Furthermore, the central link in any demonstration is a definition; yet we
cannot know what God is, but only what he is not, as John of Damascus says.
Therefore we cannot demonstrate God's existence.
Furthermore, if God's existence were demonstrable, this could only be
through his effects; yet his effects are not proportionate to him, for he is infinite,
his effects are infinite, and there is no proportion between the two. Therefore,
since a cause cannot be demonstrated through an effect which is not proportioned
to it, it seems that God's existence cannot be demonstrated.
But on the contrary Paul says, "The invisible things of God are understood
by the things that are made" (Romans 1:20). Such could not be the case unless
God's existence could be demonstrated by the things that are made, for the first
thing to be understood about a thing is whether it exists.
Response: It must be said that there are two types of demonstration. One is
through the cause, is called a demonstration propter quid, and argues from what
is prior in an absolute sense. The other is through the effect, is called a
demonstration quia, and argues from what is prior according to our perspectives;
for when an effect is better known to us than its cause, we proceed from the
effect to knowledge of the cause. In situations where the effect is better know to
us than the cause, the existence of the cause can be demonstrated form that of the
effect, since the effect depends on the cause and can only exist if the cause already
does so. Thus God's existence, though not self-evident to us, can be demonstrated
through his effects.
To the first argument, therefore, it must be said that God's existence and
other things about him which (as Paul says) can be known by natural reason are
not articles of faith but preambles to the articles of faith. For faith presupposes
natural knowledge just as grace presupposes nature and perfection presupposes
something which can be perfected. Nothing prohibits what is demonstrable and
knowable in itself from being accepted on faith by someone who does not
understand the demonstration.
To the second it must be said that, when a cause is demonstrated through
its effect, the effect substitutes for the definition of the cause within the
demonstration. This is particularly true in arguments concerning God. When we
prove that something exists, the middle term in the demonstration is what we are
taking the word to mean for purposes of the demonstration, not what the thing
signified by the word actually is (since the latter, the actual nature of the thing in
question, is determined only after we determine that it exists). In demonstrating
that God exists, we can take as our middle term definition of what this word
"God" means for us, for, as we shall see, the words we use in connection with
God are derived from his effects.
To the third, it must be said that perfect knowledge of a cause cannot be
derived from an effect that is not proportionate to the cause. Nevertheless, the
existence of the cause can be demonstrated clearly from the existence of the
effects, even though we cannot know the cause perfectly according to its essence.
Article 3: Whether God exists.
Thus we proceed to the third point. It seems that God does not exist,
for if one of two contrary things were infinite, its opposite would be completely
destroyed. By "God," however, we mean some infinite good. Therefore, if God
existed evil would not. Evil does exist in the world, however. Therefore God
does not exist.
Furthermore, one should not needlessly multiply elements in an
explanation. It seems that we can account for everything we see in this world on
the assumption that God does not exist. All natural effects can be traced to natural
causes, and all contrived effects can be traced to human reason and will. Thus
there is no need to suppose that God exists.
But on the contrary God says, "I am who I am" (Ex. 3:14).
Response: It must be said that God's existence can be proved in five ways.
The first and most obvious way is based on the existence of motion. It is certain
and in fact evident to our senses that some things in the world are moved.
Everything that is moved, however, is moved by something else, for a thing
cannot be moved unless that movement is potentially within it. A thing moves
something else insofar as it actually exists, for to move something is simply to
actualize what is potentially within that thing. Something can be led thus from
potentiality to actuality only by something else which is already actualized. For
example, a fire, which is actually hot, causes the change or motion whereby
wood, which is potentially hot, becomes actually hot. Now it is impossible that
something should be potentially and actually the same thing at the same time,
although it could be potentially and actually different things. For example, what
is actually hot cannot at the same moment be actually cold, although it can be
actually hot and potentially cold. Therefore it is impossible that a thing could
move itself, for that would involve simultaneously moving and being moved in
the same respect. Thus whatever is moved must be moved by something, else, etc.
This cannot go on to infinity, however, for if it did there would be no first
mover and consequently no other movers, because these other movers are such
only insofar as they are moved by a first mover. For example, a stick moves only
because it is moved by the hand. Thus it is necessary to proceed back to some
prime mover which is moved by nothing else, and this is what everyone means by
The second way is based on the existence of efficient causality. We see in the
world around us that there is an order of efficient causes. Nor is it ever found (in
fact it is impossible) that something is its own efficient cause. If it were, it would
be prior to itself, which is impossible. Nevertheless, the order of efficient causes
cannot proceed to infinity, for in any such order the first is cause of the middle
(whether one or many) and the middle of the last. Without the cause, the effect
does not follow. Thus, if the first cause did not exist, neither would the middle
and last causes in the sequence. If, however, there were an infinite regression of
efficient causes, there would be no first efficient cause and therefore no middle
causes or final effects, which is obviously not the case. Thus it is necessary to
posit some first efficient cause, which everyone calls "God."
The third way is based on possibility and necessity. We find that some
things can either exist or not exist, for we find them springing up and then
disappearing, thus sometimes existing and sometimes not. It is impossible,
however, that everything should be such, for what can possibly not exist does not
do so at some time. If it is possible for every particular thing not to exist, there
must have been a time when nothing at all existed. If this were true, however,
then nothing would exist now, for something that does not exist can begin to do
so only through something that already exists. If, therefore, there had been a time
when nothing existed, then nothing could ever have begun to exist, and thus there
would be nothing now, which is clearly false. Therefore all beings cannot be
merely possible. There must be one being which is necessary. Any necessary
being, however, either has or does not have something else as the cause of its
necessity. If the former, then there cannot be an infinite series of such causes, any
more than there can be an infinite series of efficient causes, as we have seen. Thus
we must to posit the existence of something which is necessary and owes its
necessity to no cause outside itself. That is what everyone calls "God."
The fourth way is based on the gradations found in things. We find that
things are more or less good, true, noble, etc.; yet when we apply terms like
"more" and "less" to things we imply that they are closer to or farther from some
maximum. For example, a thing is said to be hotter than something else because it
comes closer to that which is hottest. Therefore something exists which is truest,
greatest, noblest, and consequently most fully in being; for, as Aristotle says, the
truest things are most fully in being. That which is considered greatest in any
genus is the cause of everything is that genus, just as fire, the hottest thing, is the
cause of all hot things, as Aristotle says. Thus there is something which is the
cause of being, goodness, and every other perfection in all things, and we call that
The fifth way is based on the governance of things. We see that some
things lacking cognition, such as natural bodies, work toward an end, as is seen
from the fact hat they always (or at least usually) act the same way and not
accidentally, but by design. Things without knowledge tend toward a goal,
however, only if they are guided in that direction by some knowing,
understanding being, as is the case with an arrow and archer. Therefore, there is
some intelligent being by whom all natural things are ordered to their end, and
we call this being "God."
To the first argument, therefore, it must be said that, as Augustine
remarks, "since God is the supreme good he would permit no evil in his works
unless he were so omnipotent and good that he could produce good even out of
To the second, it must be said that, since nature works according to a determined
end through the direction of some superior agent, whatever is done by nature
must be traced back to God as its first cause. in the same way, those things which
are done intentionally must be traced back to a higher cause which is neither
reason nor human will, for these can change and cease to exist and, as we have
seen, all such things must be traced back to some first principle which is
unchangeable and necessary, as has been shown.
Translation by David Burr [email@example.com]. See his home page. He indicated that the translations are available for educational use. He intends to expand the number of translations, so keep a note of his home page.
Paul Halsall Jan 1996