St. Thomas' SIMPLEST Proof for the Existence of God (Aquinas 101)

Study abroad in ROME with the Thomistic Institute!
Spend the 2025 Spring Semester studying the ancient and medieval Roman intellectual tradition right in the heart of the Eternal City.

We've gone through St. Thomas Aquinas's Five Ways for proving the existence of God. But, did St. Thomas have more arguments for proving the existence of God? The answer is yes! In this episode of Aquinas 101: The Five Ways, join Fr. James Brent, O.P., a Dominican friar from the Province of St. Joseph, as he presents a simple argument for the existence of God from St. Thomas Aquinas's Summa Contra Gentiles.

Subscribe to our channel here:

--

Aquinas 101 is a project of the Thomistic Institute that seeks to promote Catholic truth through short, engaging video lessons. You can browse earlier videos at your own pace or enroll in one of our Aquinas 101 email courses on St. Thomas Aquinas and his masterwork, the Summa Theologiae. In these courses, you'll learn from expert scientists, philosophers, and theologians—including Dominican friars from the Province of St. Joseph.

Enroll in Aquinas 101 to receive the latest videos, readings, and podcasts in your email inbox each week.

Help us film Aquinas 101!

Want to represent the Thomistic Institute on your campus? Check out our online store!

Stay connected on social media:

#Aquinas101 #ThomisticInstitute #ThomasAquinas #Catholic #science #existenceofgod

[tibbar]

Disclaimer: I believe in God.
Observation: I know of one or two Christians who came to belief through logic, and they return to this discussion almost daily. I know particular individuals fitting this description who despite claims of Christianity, are still profoundly mean.
In contrast, I know people who read the words of Christ about love and forgiveness. The message resonated in their hearts and they became some of the most loving, empathetic people I have met in 63 years. Christianity is defensible by logic, but until it affects the heart it remains fruitless.

[tommore]

This is some of the most important stuff on the internet. Sanity. Meaning. What these things are. Can anyone make philosophical sense out of reality without Aquinas' Final Cause?

[tonyl]

Was worth a mention that it also raises the question about how and why the human mind perceives and grasps order rather than just being a mechanical effect of the order.

[reyreyes]

The fifth way, the argument from "order, " is premised on the other arguments - the series of motion, series of efficient causality, contingency to necessity, and gradation of perfections––All of these arguments point towards the concept of order, which is why the fifth way is implicitly connected to the other proofs. Critics of the fifth way often overlook these essential connections among the five ways.

It is important to note that the four preceding ways are fundamentally rooted in the fact of motion and change (the first way). St. Thomas Aquinas starts the proofs with the first way because it is the most evident. From there, he proceeds to the least evident (the fifth way) which leads to the existence of Ipsum esse as the first mover, first cause, necessary being, all-perfect, and the intelligence behind this order.

[greggloveland]

A wonderful explanation of a phenomenon we all observe! Common sense refined!

[okj]

Hey could you please make a video on purgatory. It’s pretty confusing. Love your content btw

[namesecondname]

Awareness does not evolve from rocks. Pretty easy once you go straight to truth.

[myobnvm]

Thank you very much, very good explanation. God bless!

[richardsasso]

Father Mulcahy makes some excellent points here.

[jimnewl]

This is not a demonstration of God's existence. It is a loose restatement taken from the actual proof, which is known as the fifth way in the Summa Theologica, and appears in the SCG as follows:

"Contrary and discordant things cannot, always or for the most part, be parts of one order except under someone’s government, which enables all and each to tend to a definite end. But in the world we find that things of diverse natures come together under one order, and this not rarely or by chance, but always or for the most part. There must therefore be some being by whose providence the world is governed. This we call God." (SCG 1:13)

In other words, to be ordered means to be ordered to some end, and to be ordered requires the existence of an orderer. This orderer we call God.

If the statements in SCG 3:38 were a proof of God's existence distinct from the actual proofs at the beginning of Book One, they would have appeared there and not in Book Three, long after God's existence has been established.

[godfreydebouillon]

I'm new to and woefully ignorant of Thomism, so correct me if im wrong.
This is basically the Teleological Argument (in a nutshell)?
It seems that everything has a final cause (it is going toward an end). Rather its a human, a rock or a planet. Rocks are directed toward hardness for example, as opposed to say a blob of slime, which is not. Planets are directed toward sphereness (if thats a word) and to orbiting stars, wheras nebula are not. Humans have hearts that are directed towards pumping blood, but my elbow is not. Humans are directed toward things like reasoning and sexual morality, but rabbits are not.
Those things that i described as "not" directed toward the ends i mentioned, are directed toward other ends.
All of these things are ordered. What is the cause of or reason for this ordering and directedness? If there is no cause or reason for this directedness, then nothing is the explanation.
However, nothing doesn't direct things. Rocks should be like sponges sometimes, and other times they should be hard. Gravity too is directed toward an end, but, gravity should pull things together sometimes, and at others, repel them. Sometimes maybe both at the same rime, ripping things apart.
"Nothing" doesn't direct the universe. Therefore, the universe is directed by SOMETHING that either has a mind, or lacks a mind. Things without a mind do not produce things that behave and interact in according to order, every single time. Therefore the universe is directed and ordered by something with a mind, and this is what we call "God".
And of course, if one is an atheist, dont respond back and say "sure things occur in an ordered way, with no directedness, look at snow flakes, crystal structures, evolution etc ". Thats question begging. The question is "Why?" do we see those things, and not random unordered things. See above.
If anyone reads all that, feel free to tell me where my understanding is correct, incorrect, or where it can be improved.
Thanks!

[markbirmingham]

Comment for traction. Fits well with 5th way, PSR (no brute facts), and general intelligibility arguments for God, by my lights.

[scottythetrex]

I honestly don't know why people find medieval arguments for the existence of God persuasive. These arguments were developed before we knew almost anything about the natural world. As to why there is order, almost everything can be explained by modern theories of biology and cosmology. There are things that scientists don't understand of course, but insisting that God must be the explanation just isn't very persuasive to most educated people anymore.
If you want to believe in God that is of course your right, but you'd be better off just admitting it's faith rather than trying to create a rationale for the supernatural in an age of scientific enlightenment.

[nicopiedra]

Thanks for this. I didn't know Saint Thomas Aquinas also had this argument for God. I have the same one but I came by it on my own thinking. God bless you.

[tedgrant]

In Heaven we won't need cars because there's nowhere to go.
In fact, we won't need to do anything.
Just sleep.

[jesseb]

I'm sorry but this argument is neither simple nor proof, for it may be parried with the anthropic principle. For me, the simplest proof is any memory of any awe-striking experience.

Why? Experiences like these tend to put you "beside" yourself, where, if you know nothing else, you know for sure that you are real and a single-point consciousness. Which forces the real questions: why am I here? At this time in history? Born to these parents? On this planet? Why am I me and not you? Etc. It's not bad, it's just so oddly particular that there can only be one answer: God.

Or simply put: If consciousness, then God.

[TedSeeber]

The interesting thing about this argument is that it can also be generalized as a comparison between theocratic and antrocentric methods of organizing society. The anthrocentric will invariably be more chaotic and harder to deal with.

[reznet]

I actually would disagree with this argument. I think it's more fundamental than observing 'order'. Even if you observe disorder it would speak to the existence of God since disorder requires an ordered set. In other words, in order to roll the dice, you have to HAVE dice. Even if the outcome is random, randomness only occurs within a bounded order. This is a more flexible argument that necessitates God with or without order since there is always an 'order' in every possible universe. Similar to the Scotist argument for God.

[PInkW]

Either God made the universe
Or
Chance made the universe
The universe is ordered
So Chance is out

[progidy]

0:45 we actually see parts of the periodic table that don't display order. In fact, the very first element, hydrogen, could be put or grouped with three different columns. It's currently grouped on the left with the alkali metals, despite not being an alkali metal. And one big reacts to things fit the other medals in its column react with, you get strikingly different results. Hydrogen chloride is a corrosive and deadly gas, sodium chloride is yummy table salt. Most periodic tables show hydrogen kind of separate and hovering above the column for these reasons. I guess that makes your argument a bad argument.