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The Domestic Aquinas Project

Making the Summa Applicable to Families

Prima Pars

Question 2: Treatise on the One God 

Article 1: Is the existence of God self-evident?

Summary of Argument: 

One cannot admit something that is self-evident to not be.  For example, it is self-evident that I have a body.  Thus, I can’t admit to not having a body (contrary to what Descartes believes).  However, one, though he be a fool, could admit there to being no God and thus, the existence of God is not self-evident to us. 


Any proposition is self-evident if one knows the essence of the proposition.  So, the proposition that ‘man is an animal’ is self-evident because we understand both terms.  Animalness is contained in the species of man, namely, that all animals have senses and emotions.  We understand both the animal, sense aspect and our man, rational aspect.  So the proposition is considered to be self-evident. 


But, with the proposition that ‘God exists’, we know what it means to exist, but we don’t know the essence of God as we are finite and His essence is of an infinite nature.  So it is self-evident to God that this proposition is true, but not to us.   We have to come to know that God exists through things whose essences we can understand like nature and creation. 

Taking it Home:

1.  All of us desire to be happy.  This desire for happiness is a desire for God Himself.  This is an ongoing reminder to our children.  Everything you continually want, and desire as far as things go, is an echo, a reminder that what you truly desire

is God Himself.

​2.  This desire to be happy is in us a real, tangible

way – it is part of our nature, but knowing God is the

fulfillment of it is in us in a general and confused

way.  We know that having all the Lego in the world,

the best wine, the power, money, etc. won’t make us

happy, but we don’t automatically know that it is

God Himself who will.  St. Thomas gives the

example: it is like seeing a man approaching you.  You know it is a man, but you don’t know that it is Peter.  We know something out there will make us happy, but don’t know necessarily that it is God.  If it was self-evident, we wouldn’t need to evangelize now would we?


Thus it is our job as parents to not spoil the children with stuff, adventures, technology and so forth, but to bring them continually to the Blessed Sacrament where Christ is truly present.  And to teach them to adore and worship for only in Him will we find happiness.

Article 2:  Can it be demonstrated that God exists?


Structure of the Argument:


It can be demonstrated that God exists and we can understand Him through His creation.  This type of demonstration is called ‘a posteriori’, namely, arguing from the effects to the cause, from things that exist to the existence of a creator.  This can happen simply because every effect must have a cause.  Thus, if we have a world with plants and trees and animals that is ordered and beautiful and so forth, there must be a cause for all of this that pre-exists it all. 


The key is that we can know that God exists by looking at creation.  However, the further the effects are from the cause, the less we can know about the essence of the cause.  Since, creation is finite and God is infinite, the distance between the effect (creation) and the cause (God) is immense.  The result is that we can’t know God perfectly in His essence by looking at nature, BUT we can know that He exists.


Family Take Home:


Being out in nature provides constant

opportunity to get to know more

about God.  Whenever my children

have a doubt about the existence of

God, I simply go to a field, pick a wild

flower and ask how it came to be

there.  Then I follow up with: where

did the mother flower come from?

And the one before that? And that

one? And so forth.  There has to be

a beginning at some point and that

beginning must have no beginning

and hence we call God the Uncreated Creator. 


Secondly, take the same flower and ask what we can know about the creator of the flower.  He must have a sense of beauty, knows how to keep the species alive, created a system of reproduction, nutrition, and order.  The creator must also be able to give this plant the spark of life.  Only one who is existence Himself can give the gift of existence that is passed on from flower to flower.

Article 3: Whether God exists?


Structure of the Argument:


The opposition would state that if God is infinite goodness then there shouldn’t be evil in the world. 


St. Thomas proves God’s existence in 5 ways:


1.  Motion:  In order for things to be in motion they must first be moved.  What is put into motion must be put into motion by another, and another before that, and another before that till eventually you arrive at someone who is unmoved and begins all motion.  This unmoved mover we call God.

 2.  Efficient Causality:  By efficient cause here we mean the cause that causes change, that brings things into existence or out of existence.  This argument is similar to the first, namely, that there must be a first.  Every cause has an effect.  If you take away the cause then there is no effect.  When we look at creation and the world around we take in a cacophony of causes and effects, of things coming into being and going out of being.  There had to be a beginning that was the first cause without being caused itself.  This first cause is God.

 3.  Existence: In order for things to exist, there must be something that brings it into existence.  The principle is this:  “Nothing comes     from nothing.”  If nothing comes from nothing then it would be possible to have a beginning of our world in nothingness.  There had to be something that existed simply, on its own first and then gives existence to everything that exists.  Thus, all things that exist, do so because they have received or been gifted existence.  This giver of existence, we call God.

 4.  Different Modes of Existence:  Everything that exists receives their existence ultimately from God (as proven in argument #3).  However, everything that exists does so in different modes.  Each thing, a car, a person, a mouse exists according to the nature that it has been given (called essence).  What is interesting is that there are some things that are greater than others.  A person is greater than a mouse because it has a higher form of being.  If there are things that are better than others, then it makes logical sense that there is a best.  The best would be that thing that exists perfectly with the highest form of being and thus being most beautiful, most good, most unified, and most true and this we call God.


5.  Order:  The world works in perfect order with all manner of beings living and surviving and acting according to their nature.  This harmony can only come from an intelligent being.  Because, something with no intelligence (like a rock) cannot act towards a specific end.  A rock can’t throw itself at Goliath’s head.  The intelligent design bespeaks an intelligent creator whom we call God.


He replies to the objector: God doesn’t allow evil to exist in the world unless there is a good that He can produce out of it. 

Family Take Home:


The take home for this article is to ask what are more proofs of God’s existence.  Peter Kreeft in his Shorter Summa (Ignatius Press, 1993) offers other proofs:


1.  From St. Anselm: it is more perfect to exist than not to and the most perfectly conceivable being could only be perfectly conceivable it exists.


2.  Augustine:  we can know absolute, eternal truths, truths that don’t change.  This is a divine attribute and not human.


3.  Newman: the fact that we have a conscience proves survival of the fittest wrong.  We feel guilty when we step on another to gain.  This could only be implanted in us from God. 

4.  CS Lewis: We have an innate desire for God (or beatitude to be eternally happy) and this desire would be futile if it couldn’t be realized.  Therefore there must be a God that quenches our desires.

5.  Von Balthasar: Beauty:  if there is beauty there must be a most beautiful that all beauty comes from.

6.  Existential:  from experience – if there is no God then life is meaningless.

7.  From experience: many people have had mystical experiences.

8.  From experience: we instinctively pray in a crisis.

9.  Pascal’s Wager:  to wager your bet on God’s existence and living accordingly leads to a far greater chance of wining then betting against his existence.  And if you lose betting on the God side, then you’ve still lived a life that is happy for you lived virtuously.

10.  From miracles.

11.  From providence: God’s direction and moving in our lives.

12.  From authority: the smartest folk to have ever lived believed in God’s existence.

13.  From Jesus: He is either the biggest liar or is God enfleshed.

Prima Pars

Question 3: On the simplicity of God


Article 1: Whether God is a body?


Structure of the Argument:


Now that we now that God does in fact exist, we now seek to understand what/who God is.  The first question asks whether God has a body or in other words: whether God is made of parts like a body is.












He gives three arguments why God doesn’t have a body:


  1.  In order for bodies to be in motion (motion includes changing from one state to another) they have to be moved (or instigated to change).  It was found in the last question that God is the unmoved mover.  He is the very first mover and yet remains unmoved.  He is the instigator of all change and yet isn’t changed Himself.  Thus, God cannot have a body.

  2.  All things that exist move from potentiality at actuality.  For example: we all have the potential to learn.  Our reason has potentiality to know everything and as we gain knowledge our reason is more actualized.  So for the most part, potentiality comes first.  Yet, every potential, in order to be actualized, must have something that has been actualized to actualize it.  In this way then, actuality comes first or rather there is a very first actuality and that must be God.  Therefore there must nothing in potential in God for there would be nothing to actualize it. Hence, we know God to be pure actuality.  Every body has potential.  Thus God has no body.


3.  There are two types of bodies: living and non-living.  Living bodies are animated by soul (vegetative, animal, or rational).  A living body needs a soul to be living.  The body is dependent upon this spark of life.  Thus, God can’t have a body for He did He would be dependent on something to animate Him and then we couldn’t call Him God.


Family Take Home:


Scripture is often seen giving physical attributes to God.  We

know that Christ sits at the right hand of the Father or Moses

saw the back of God.  Hearing the voice of God infers a set of

vocal chords and so forth. 


It is important to discuss with your children that God has no

body.  Scripture uses these literary tools (anthropomorphisms)

because we have a body and it helps to understand Him and

His ways better.


However, this being said, God (in Christ) does have a body and we will see Him literally face to face.

Question 3: Article 2:  Is God composed of matter and form?


Structure of the Argument:


It is impossible that there be in matter in the composition of God for the following reasons:


1.  As looked at above: God has no potentiality in Him as He is pure act.  Thus He can have no matter in Him for all matter has a degree of potentiality.


2.  Matter becomes something, is something

good when it receives its form.  Matter

without form (what the ancients called Prime

Matter) doesn’t exist.  Thus, we can say that

matter is perfected by its form as a pile of

bronze is perfected by receiving the form

impressed upon by an artist (to make a

statute for example).  Now God, doesn’t

participate in any goodness, but is rather

the author of goodness.  Hence, God is good

essentially, in who He is in Himself, and

things that have a form (and thus exist) are good because they receive a form from Him – they have a participated good.  So, God can’t be composed of matter.


3.  Form gives matter a nature, an essence, a manner in which it is to be and act.  The vegetative soul of a tree forms the matter that makes a tree a tree and informs the tree in how it is to grow and reproduce and so forth.  Now God is the first agent, the first efficient cause and thus is a form only.  Hence, we say: God is Spirit.


Family Take Home:


If we are teaching children about whom God is, we’ll have to answer the question about whether God has emotions.  For St. Thomas, emotions are a function of the sensual soul and are connected with our bodies.  Our soul is one, but we can look at under three aspects: 

1.  The vegetative aspect (plants have this as well): the part of our soul that vivifies our body, keeps digestion going, grows our hair and so forth.

2.  The sensitive aspect (animals have a vegetative

and sensitive soul):  the part of our soul that gives

us our senses.  Along with this, is also memory

(which is stored in our brain) and our emotions. 

3.  The rational aspect (had by humans, angels and

God): the part of our soul not directly tied to a part

of the body.  The ‘part’ that doesn’t die and is never



If God doesn’t have a body, then He can’t have

emotions.  We attribute emotions to Him as we

attribute a ‘right hand’ to Him.  It helps us

understand Him in human terms. 


Now this doesn’t mean that God is cold and unfeeling.  On the contrary, He is pure beauty, pure goodness, pure love and so forth.  He is intrinsically these things and thus all His acts flow from these vs. ourselves.  We are not intrinsically love and have to choose to love and not to. 


So when God is angry in the Old Testament and spites the world with a flood, or destroys Sodom with fire, it is an act that is full of love, justice, goodness and all that He is. 

Question 3: Article 3: Is God the same as His essence or nature?


Structure of the Argument:


God is the same as His essence or nature.  This is not so with man.  Socrates is a man.  He is not humanity or said in another way, all humanity is not represented in Socrates.  Humanity is a species of animals that have reason.  It is the rational soul that is the form of man and defines our species.  Socrates as an individual man is a concrete individualization of humanity and is individualized through having a body.  Thus, for us humans: our essence or nature is our rational soul, which is different than myself as a man.  God has no matter or body.  He is therefore His own essence.  Which makes sense as God is perfectly simple and there is no composition in Him. 


Family Take Home:


The understanding of our own being and essence is important to understanding ourselves.  We receive existence from God when He creates a rational soul from nothing at the time of our conception.  Our essence is our rationality, which makes us a part of the species of humans. 


The significant conclusion from this in our western

world is that there is NO female or male soul.  If

there were then we would be two different species

and wouldn’t be able to mate.  Male and female are

just two modes of existing in the species.  This is

important when discussing ‘gender issues’ in our

world today.  The claims of being female on the

inside and having a male body are impossible.  A man may feel feminine, but he is still a man with a rational nature.  I only exist because I have a body and my body is masculine and thus I am a male.


God is His essence.  God is existence.  There is nowhere where He is not. 

Question 3: Article 4:  Are essence and existence the same in God?


Structure of the Argument:


God is not only His own essence, but is also His own existence.



1.  If something exists in a thing besides its essence, that thing must be caused either by the essence or by something exterior to it.  So in man, our human nature (rational soul, our essence) is the cause of laughter in man.  In hot water, the heat is added to the water by an exterior agent like fire.  So, if existence and essence are different in something then either an essence is causing its own existence or the existence is caused by something else.  In man, we are not the cause of our existence.  God is.  God gives life to the human matter formed from the sperm and the egg.  In God, as He is the First Cause or the Cause of all causes, there is nothing left to cause existence in Him so therefore He must be His own existence.

2.  Existence is that which makes something

actual.  “In the beginning God created the

Heavens and the Earth,” (Gen. 1:1).  So in

things created, the matter is seen as passive

and the existence is seen as the active force. 

But God is pure act and there is no potentiality

in Him so He must be His own existence.


3.  A log on fire is not fire but is only

participating in the fire.  We are not existence,

but participate in the existence given to us by

God, like a log participates in fire but is not the fire itself.  If God was not His own existence He would need to be participating in something, but as He is the First Cause there is nothing prior to Him to participate in.


Family Take Home:


This article puts new on meaning on I Cor. 6:19, “You are not your own.”  We are not our own existence.  We exist only because we participate in the being, in the existence that God has gifted to us.  This gift of life is so great, so precious, so infinite, that it is one of the greatest goods known to man.


I used to believe that God must be somehow diabolical for it seemed that He created people He knew would suffer in Hell because He knows the beginning from the end.  What I didn’t understand is that being given the gift of existence is a greater good than the suffering one endures when choosing Hell.  This is a sobering thought.

Question 3. Article 5:  Whether God is contained in a Genus?


Structure of the Argument:


A genus is prior to what it contains and nothing is prior to God, thus God is not in a genus.


God cannot be a species of any genus like a god in the genus of Divine Beings.  This is because:


1.  Every species within a genus is made up of the genus plus a specific difference.  Man (the species) is in the genus animal plus the specific difference of having reason.  Now species is in a position of potentiality to the actuality of the genus.  The genus animal has the potential of receiving the specific difference of rationality.  God, being pure actuality can’t be in any position of passive receiving.

2.  Since God is His own existence and his essence (what would be the specific difference) is one with His existence, if He were a genus, He would be the genus ‘being’.  However, ‘being’ can’t be a genus as even a genus must have something that is distinct from it in order to identify it as a genus in the first place.  In order for there to be the genus animal, there must be other genus’s like plant and mineral in order to show that not everything is in that genus.  But if the genus were to be being, the only difference would have to be a genus of non-being and non-being doesn’t exist.  Thus ‘being’ can’t be a genus. 

Thus God can’t be a genus.

3.  Everything in a genus agrees in their essence and differs

in their existence.  All men in the genus Man have a rational

nature (essence) and yet each are different by their

individualized existence in a body.  Since essence must differ

within a genus, God can’t be in a genus. 


God is not the genus ‘being’ or in any genus, but rather is the principle of all being.


Family Take Home:


The take home here in this question on trying to understand what God is, is important especially in the area of ‘being’.  God is not the existence in each of us.  If He was, we could never be separated from Him.  When we believe as Catholics that God is in us, He is in us not as our ‘being’, our ‘existence’ but rather accidentally.  He is in us in such a way that He forms us and knows us, but His presence will flee from us if we are in mortal sin. 


God is the author of our being and our being is our own.  He forms our being to be more like unto Himself if we cooperate with Him: this cooperation is what we call grace. 

Question 3, Article 6:   Are there Accidents in God?


Structure of the Argument:


First of all, what does St. Thomas mean by ‘accident’? 


An accident is something that exists, but cannot exist on its own.  For example: skin colour is something that exists, but if there were no skin, there would be no skin colour.  Hence, we call the mode of being of the skin colour an accident.


It should be obvious by now that there are no accidents in God. 


First: a substance is made in some sense actual by its accidents.  Substances can’t exist without their accidents.  One can’t have skin without the skin having a colour.  And if God is prior to all, there can’t be accidents there to actualize Him.


Second:  God is His own existence and His own essence.  Existence may have other properties added to it (as in the case of a rock: hardness, colour, density), but pure existence is simply pure existence. 


Third:  God can’t have essential accidents (accidents that the substance can’t do without, for e.g.: hardness and a rock) for essential accidents are caused by the principles within the substance.  Man can laugh because he has reason.  Laughter is an essential accident caused by the gift of reason in man. Nothing can be caused in God as He is the First Cause.  So, there are no accidents in God.


Family Take Home:


This article is important insofar at it again proves

the simplicity of God.  There are no parts in Him. 

He is perfectly one in His substance. 


However, the 2nd Person of the Blessed Trinity

does ‘take on’ accidents when bread is consecrated

at the Holy Mass.  Accidents are key to

understanding the Holy Eucharist.  The essence of

the bread is no longer there – it has become the

Body of Christ.  Christ is there whole and complete, soul and divinity and holds the accidents of the bread in a localized place so that we may have eternal life when we consume Him. 


I picture it as Christ sitting crunched inside the wafer and holding all the accidents (shape, colour, taste …) of the bread around Himself so that we can receive Him.

Q. 3: Article 7: Structure of the Argument:  Is God altogether simple?


Structure of the Argument:


God is absolutely simple because:


1.  As seen in the previous articles, there is no composition in God.  He doesn’t have a body and is not a being composed of matter and form.  Neither does He have an essence different than His existence. 


2.  Every being that is composed of parts is dependent on its parts in order to be a composition.  A music composition without the parts is no composition.  But God is the First of all beings and thus couldn’t be depend on something prior to exist.


3.  Every thing composed of parts has a cause

for in order for things to unite to become

something together, there must be a something

that causes them to unite.  There must be

something that makes the flour, water, egg and

sugar to unite to make them one cake.  God is

the First Cause and thus must be uncaused.


4.  In every thing made of parts there is both

potentiality and actuality.  All the parts are

potentially the whole when united for example.

Flour is potentially a cake when united with

other ingredients.  There is not potentiality in God; He is pure actuality.

 5.  The parts in a whole can’t share in everything that the whole is.  We can’t say that flour tastes delicious, but we can say the cake does.  Thus in every composition, every thing made of parts, there is always something that is not itself.  You can have tasteless flour in a delicious cake.  In God, you cannot have something in Him that He is not.  “God, who is strength, is not made of things that are weak; nor is He who is light, composed of things that are dim,” (Hilary, De Trin. vii).


Family Take Home:


In the responses to the objectors, St. Thomas makes an important point.  The objector says that the whole of a human person is of greater worth than its parts (like its foot), hence the amputation of a foot doesn’t diminish the value of the person.  This is how we are different than God.  In the created world, things made of parts show a perfection and the perfections of creation are shown not in one simple thing, but in many complexities.


This leads us to a principle of beauty:  diversity brings beauty.  The ideology of socialism that wants to make everyone equal and the same misses this valuable nugget.  People learning different curriculums and being educated in different ways brings a beauty to society and strengthens it. 


We constantly remind our children that we are not socialists.  If one child gets a glass of milk, it doesn’t therefore mean that every child must have a glass of milk.  There is beauty in diversity in creation and there is perfect beauty in God who is perfect unity.

Q. 3: Article 8: Does God enter into the composition of other things? (Is God the ‘world-soul’?)


Structure of the Argument:


There are three errors that St. Thomas wants to debunk with this article. 

  1. God is the world-soul.

  2. God is the form of all things.

  3. God was primary matter (matter without form).


These he debunks as follows:


1.  God is the first efficient cause: The efficient cause of something can’t be at the same time its form and matter.  Just as man begets (is the efficient cause) a son, he is not the form or the matter of that son.  That son has his own matter and own rational soul (form).  Thus, God is the efficient cause of the world, but is not the form or the soul of the world.

2.  God as the first efficient cause is pure act.  He,

in His essence, is pure act.  There is no passivity in

Him.  To be in the composition with something

means that the composite acts.  For example, our

hands don’t act on their own, but they act

because the man is acting.  If God was the form

of something like the world, He would be acting

only when the world was acting as a


3.  Prime matter is passive waiting to receive a

form as the lump of clay is potentially able to receive whatever form or shape the artist gives it.  Matter is thus always going to posterior to that which is actuality. God is pure actuality, pure act and thus is not matter potentially receiving a form.


Family Take Home:


What is important here is again that God, when we receive Him in Holy Communion, He and abides in us and us in Him, is not coming into composition with us.  In technical terms, He is accidental to us.  What does this mean?  When we receive the body, blood, soul and divinity of Christ, He forms our soul (like a wearing a sweater surrounds your body).  However, as the sweater is not a part of our make up and can taken off, so Christ forming us through grace can be lost through mortal sin. 


In this way, the protestant heresy of ‘once saved always saved’ is hogwash.  We can be in the grace of God and we can lose the grace of God. 

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