St. Thomas Aquinas Paper

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St. Thomas Aquinas

St. Thomas Aquinas' First Two Ways in Proving the Existence of God

It is my view that God exists, and I think that Aquinas' first two ways presents a

successful argument for the existence of God. No doubt, the arguments have weak points

which are subjected to criticism but nonetheless, in my opinion, these propositions by

Aquinas do indeed accomplish their purpose in establishing the existence of a Greatest

Conceivable Being that is the unmoved mover and uncaused cause. I believe that this

ultimate Being is unchanging and started the universe, time and all matter and concepts

of existence. In my view, this Being is what we understand to be God.

St. Thomas Aquinas recognized that there were some people who doubted the

existence of God because, to them, logic did not allow for or explain God's existence. His

first two ways are two proofs based on logic and observation of nature in proving God's

existence to those who could not accept or believe God on faith alone. Aquinas' first way

is based on motion. He calls it the most obvious way. This first argument, the Argument

from Motion, tries to prove the existence of God as the first mover which is unmoved.

Now, it is certain as a matter of sense-observation that some things in this world are in

motion. Whatever is in motion, Aquinas states, is moved by something else. Aquinas then

defines one type of motion as the reduction of something from potentiality to actuality,

and says that nothing can make this movement except by something that is already in

actuality in the same respect as the first object is in potentiality. For example, something

which is actually hot, like fire, makes something which is potentially hot, like wood, to

be actually hot. In this way the fire moves and alters the wood. Now, it is not possible for

the same thing to be, at the same time and same respect, in actuality and in potentiality.

For instance, what is actually hot cannot simultaneously be potentially hot, though it may

simultaneously be potentially cold. So, it is impossible that in the same respect and same

manner anything should be both mover and moved. In this, Aquinas means that nothing

can move itself. Therefore, if something is in motion, it must have been put in motion by

something else, which must have been put in motion by yet another thing, and so on.

However, this cannot go on to infinity because there would never have been a first mover

and, consequently, no subsequent movers. After all, second movers do not move except

when moved by a first mover, just as a stick does not move anything except when moved

by a hand. Thus, this leads to the conclusion that there is a first mover which is not

moved by anything, and this first mover is what we understand to be God.

Summarizing Aquinas' first way, the argument states that objects are in motion,

and if something is in motion, then it must be caused to be in motion by something

outside of itself. That is, an object in motion is put in motion by some other object or

force. There can be no infinite chain of movers/movees so there is a first, unmoved

mover. Therefore, in conclusion, the unmoved mover exists and is called God.

Aquinas' second way in proving God's existence is based on the nature of

efficient causation. Now, causation itself is "making to be" in the sense that the cause

makes there be the result. Efficient causation, however, is the production of the result, or

the activation from being merely possible or potential into accomplished fact. Thus, the

efficient cause is what brings about the result to be effectively realized as actual. In the

observable world we discover an order of efficient causes, but no case is found, or ever

could be found, of something efficiently causing itself. Such a thing would have to be

prior to itself, which is impossible. Now, it is impossible to go on forever in a series of

efficient causes. This is because in every ordered series of efficient causes the first

member of the series causes the intermediate member or members (whether the

intermediate be one or many members), which in turn cause the final member. If you

eliminate a cause you eliminate its effects, so there will not be final or intermediate

members in the series unless there is a first member. Given if the series goes on forever,

then there will be no first efficient cause, and so there will be no intermediate efficient

causes and no final/last effect, and this would be an open mistake which is obviously

false. For example, a table is brought into being by a carpenter, who is in turn caused by

his parents. Evidently, we cannot go on to infinity. Therefore, one is forced to suppose

some first efficient cause, to which everyone gives the name ‘God'.

In summary, Aquinas' second way states that no object created itself, or is found

to be the efficient cause of itself because if this was the case, the object would have to be

prior to itself, which is impossible. Consequently, we see that one object's existence is

simultaneously dependant on the other. However, there cannot be an endless string of

objects causing other objects to exist so there must be an uncaused first cause. Therefore,

in conclusion, the uncaused cause exists and is called God.

What are the main ideas in Aquinas' first two ways? Basically, I perceive that his

arguments are equivalent to the proposition, "There is no thing that came from nothing."

The first argument is about motion, which means every kind of change, not just local

motion or change of place, but also ripening, heating, etc. There must always be a cause

for any change, a "moving" cause. The second argument is very similar, about "efficient"

causes. The difference between a "moving" cause and an "efficient" cause is that the

moving cause produces another state of something while the efficient cause produces

existence. Therefore, it is my view that without a moving cause and an efficient cause

there would simply be "nothing" and the universe and concept of time would cease to

exist. On that account, Aquinas' first two ways seem to present a successful argument for

the existence of the creator God.

As with all arguments attempting to prove the existence of God, Aquinas' first

two ways are subjected to possible criticisms, objections and/or weak points. To begin

with, consider Aquinas' first way, the Argument from Motion. Aquinas says that the line

of movers cannot go on to infinity, which common sense would tell you to be true. He

thus establishes the arbitrary endpoint of God. A problem arises in that this argument

could always be tested to be false by asking the question, "What moved God?" Aquinas

would probably answer that nothing moved God because God has always existed. Still, to

prove his first argument to atheists, Aquinas must accompany it by another argument that

proves God has existed forever. Then God would not need to have been moved since He

would always have been. This would make for a kind of circular flaw in logic or paradox,

in that Aquinas could not prove God existed until he proved God has existed forever, and

he obviously cannot prove that God has existed forever until he proves that God exists at


In defense against this and other criticisms, it is my viewpoint that a measure of

faith is necessary to believe in God's existence. My conviction is that God's infinity

proves that he has existed forever. When trying to understand certain of God's

incomprehensible attributes, like how He has existed forever, it is necessary to realize

that we as humans are finite beings who are incapable of fully comprehending the infinite

being of God. God is the infinite God. Nothing or no one created Him, or brought him

into existence. God is the Greatest Conceivable Being, without genealogy, and having

neither beginning of days nor end of life. Unmistakably, it is vital to have an element of

faith to believe in God's existence for it is impossible for finite minds to understand how

God can exist without having a beginning. When atheists and other non-believers try to

consider God, they try to make the facts about Him fit within their limited capacity to

comprehend and understand. It appears they do not want to believe that there is more of

God than their minds can contain and comprehend. Seemingly, the attempt to fully

understand God is like trying to place the infinite One into a finite space; that is


Another weak point that appears in Aquinas' arguments is that even if they do

provide certainty about the existence of an unchanging changer or Greatest Conceivable

Being that could not have failed to exist, the arguments fail to prove the existence of the

theistic God. Since the theistic idea of God is a Being of perfect goodness, omnipotence,

and omniscience, an issue arises. How do we know, for example, that the unchanging

changer isn't evil or slightly ignorant? Well, aside from using logic and our natural

powers of reasoning to deduce whether the ultimate Being is supremely good or not,

observe that an element of faith is once again necessary in this scenario. Finally,

regarding the Argument from Motion, who is to say there was only one original Prime

Mover? Why not two? Better still, why not a whole team of Gods, working on the project

together? Perhaps our universe is one of many attempts, some good, some botched. In

defense against this criticism, I believe that it is hard for humans to accept that some

things may not have a reason, but there might be instances where this is actually the case.

It is my view that there may be some questions that simply may not be answered

correctly or known in our lifetime as mortals, or contingent beings.

Criticisms regarding Aquinas' second way, the nature of efficient causation, also

result in various objections to the argument. First of all, it seems like Aquinas decides,

arbitrarily, that the first efficient cause is called "God" by everyone. One may argue that

given there is some First Cause, it does not follow that there is God. It does not follow

either that there is just one such cause, or that this being has the other attributes ordinarily

ascribed to God. The defense against this criticism could be to analyze what is involved

in having full spontaneity, free from any conditions or prompting. That is, the First Cause

has all the independence, capabilities, and richness involved in absolute spontaneity and

freedom from conditions. In other words, if these lofty claims did not apply to God, what

then? Would that prospect involve "dragging down" God from the exalted status and

character involved in being the First Cause? If so, then that very fact is proof enough that

these traditional ideas of God are true after all.

Also, one may argue that in this argument, even though each being in the infinite

series has a cause, the infinite series itself has no causal explanation. For example, people

imagine that, by making the chain of causes reach back to infinity, they can somehow

evade the force of this argument. For instance, if the series went back forever, the need

for something to start it is irrelevant. However, and in defense against this criticism,

Aquinas had argued that the world in principle could have existed forever. In fact, the

world began to exist, but that need not have been so. If the world had existed forever, it

would still be completely dependant on God to exist. It would still not have existed of

itself. The world would still be created as being made to exist by God. Indeed, since God

is not subject to time, and so is not "in" time, one might well say there is no time-related

or temporal priority of God to the world.

Finally, Aquinas' first two ways seem related to questions about the universe. The

argument from motion and argument from the nature of efficient causation give rise to

questions like "Has the universe always existed, or did it have a beginning in time?" If

the universe did have a beginning, then what was there before? And what about the size

of the universe. Is it infinite or finite? It is hard to imagine infinity, but if the universe is

finite, it does not make sense to ask what is beyond it, because the universe is all there is.

In conclusion, I believe that a person would have to be omniscient and

omnipresent to be able to say "there is no God" from his own pool of knowledge. We as

humans are contingent, or finite beings, and only someone capable of being in all places

at the same time with a perfect knowledge of all that is in the universe can make such a

statement that "there is no God" based on the facts. In other words, a person would have

to be God to say there is no God.

Still, proving the existence of God to atheists and non-believers is a worthwhile

task. If someone did come up with a complete, foolproof argument for the existence of

God, the people of the world would have no choice but to believe in His existence.

However, even though St. Thomas Aquinas makes a worthy and in my opinion successful

effort, I believe such a task is not yet possible through logic and reasoning alone. There is

an element of faith that must be present for people to believe, and if that element is not

there, no matter how foolproof an argument seems to be, there will always be those who

do not believe. For me, Aquinas' first two ways are successful in proving God's existence

but my belief in the existence of God is on the basis of faith. Therefore, if that element of

faith is not there, I do not think you can completely prove God's existence to everyone.


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