Five Ways to Prove God Exists (Aquinas 101)

Summary

This video script explores Thomas Aquinas' Summa Theologiae, focusing on his famous five ways or proofs for the existence of God. It highlights Aquinas' belief that humans can know God's existence through natural reason, without relying solely on faith or scripture. Aquinas uses examples from nature, such as motion, causality, and the perfection of beings, to argue for the existence of a first mover, a first cause, and a perfect being. The script emphasizes Aquinas' detailed reasoning and the possibility of natural theology in understanding God's presence in the world.

Takeaways

• 📚 Thomas Aquinas's *Summa Theologiae* is divided into three main parts: God's presence in creation, God's presence through grace, and God's presence in Christ and the Church.
• ❓ One of Aquinas's major questions is whether God exists, and he tackles this through his famous five ways or proofs.
• 📖 Aquinas teaches that human beings can know God's existence not only through faith but also by using natural reason, supported by the Bible and ancient philosophers.
• 🌍 Romans 1:20 and Wisdom 13:1-9 suggest that humans can know God exists through observing the natural world, even without reading the Bible.
• 🧠 Aquinas found evidence of natural knowledge of God in ancient pagan philosophers, confirming that human intelligence can recognize God's existence.
• 🛤️ Aquinas acknowledges that developing natural knowledge of God is difficult and that many factors can hinder its perfection.
• 🔍 The five ways demonstrate how human reasoning from nature can infer the existence of God, using visible effects to identify an invisible cause.
• 🔥 One analogy used by Aquinas is inferring the existence of a fire from the sight of smoke, much like inferring God from the order of nature.
• ⚙️ Each of the five ways addresses different aspects of nature: motion, causality, contingency, perfection, and purpose, each leading to the conclusion that God exists.
• 💡 Aquinas encourages ongoing meditation on the presence of God through these arguments, as they can deepen understanding of God’s role in the world.

Q & A

What is the primary focus of Thomas Aquinas's *Summa Theologiae*?

The *Summa Theologiae* primarily focuses on the presence of God in creation, in the souls of the just by grace, and in Christ and His mystical body, the Church.

What are the five ways of proving God's existence according to Thomas Aquinas?

The five ways are: the argument from motion, the argument from causality, the argument from contingency, the argument from degrees of perfection, and the argument from design or order in nature.

How does Aquinas suggest human beings can know the existence of God?

Aquinas suggests humans can know God's existence either by faith (through scripture) or through natural reason, using observations of the world around them.

How does Romans 1:20 and the Book of Wisdom 13:1-9 support Aquinas's view on natural knowledge of God?

Both passages indicate that people can know God's existence through the beauty and order of the natural world, even without having read the Bible.

Why does Aquinas believe some people struggle to develop their natural knowledge of God?

Aquinas believes that cultural circumstances, lack of intellectual development, or attachments to sin and false philosophies can prevent people from fully developing their natural knowledge of God.

What analogy does Aquinas use to explain how we can infer the existence of God?

Aquinas uses the analogy of inferring a fire from seeing smoke or inferring an infection from symptoms like a sore throat, showing that we can know invisible causes from visible effects, just as we can infer God's existence from nature.

What is the key principle behind all five of Aquinas's ways of proving God's existence?

The key principle is that we can know God's existence by reasoning from the visible effects of the natural world to the existence of an ultimate cause or explanation, even if that cause (God) is invisible.

What is the 'first way' in Aquinas's five proofs, and what does it argue?

The first way is the argument from motion, which argues that there must be a first mover (an unmoved mover) that is the ultimate source of all change and motion in the universe.

What is the 'second way' and how does it differ from the first?

The second way is the argument from causality, which states that there must be a first cause (an uncaused cause) responsible for the chain of cause and effect in the universe, unlike the first way which focuses on motion.

How does Aquinas's fourth way argue for the existence of God?

The fourth way, based on degrees of perfection, argues that since things in the world exhibit varying degrees of perfection, there must be a source of maximum perfection, which is God.

Outlines

00:00

📚 Overview of Aquinas's Summa Theologiae

This paragraph introduces Thomas Aquinas's *Summa Theologiae*, a three-part work exploring God's presence in creation, grace, and Christ. It is framed as a meditation on God's presence, addressing one of the most significant questions—whether God exists. Aquinas tackles this question with his five famous proofs for God's existence, which this episode will outline. Aquinas acknowledges both faith-based and reason-based approaches to knowing God, referencing biblical passages (Romans 1:20 and Wisdom 13:1-9) that support natural knowledge of God's existence through the observation of the natural world.

05:04

🔍 Aquinas and Natural Knowledge of God

Here, Aquinas's belief that human beings possess a natural knowledge of God is explored. He draws on both biblical and philosophical traditions, showing that people who have never read the Bible still offer arguments for God's existence. Aquinas posits that natural knowledge of God is developed through reasoning and experience of the natural world. However, this knowledge is not always explicit or clear and requires intellectual development. Despite challenges, some individuals, through dedicated study, can reach a profound understanding and offer rigorous proofs for God's existence.

🔥 Reasoning from Visible Effects to Invisible Causes

Aquinas's reasoning method is explained, comparing our inference of God's existence to how we infer invisible causes from visible effects in daily life. For example, just as we deduce the presence of a fire from smoke or an infection from symptoms, we infer the existence of God from the beauty and order of the natural world. Aquinas claims that while God is invisible, we can reason from our observations of the world to an understanding of an ultimate cause—God. This line of reasoning underpins his five proofs for God's existence.

🌱 The Seed of Natural Theology

This paragraph discusses how the reasoning behind God's existence, like a seed, can grow through intellectual study. However, it can also be hindered by negative factors like sin, false philosophies, or denial. Aquinas acknowledges that while atheism and agnosticism are possible and can even become widespread, he asserts that natural theology—the knowledge of God through reason and the natural world—remains a possibility. Aquinas exemplifies the development of natural knowledge into a structured philosophical understanding of God's existence.

🛤️ Aquinas's Five Ways: A Path to Knowing God

This paragraph introduces Aquinas's famous 'five ways,' or proofs for God's existence, each rooted in experiences of the natural world. The first way argues from motion to a first unmoved mover; the second from causality to a first uncaused cause. The third considers contingent beings and concludes there must be a necessary being. The fourth reasons from the gradation of perfection in beings to the existence of a perfect being. The fifth way sees unintelligent beings acting towards ends, implying a higher intelligence directing them. These sketches provide a starting point for further contemplation of God's presence.

Keywords

💡Summa Theologiae

The *Summa Theologiae* is the most famous work of Thomas Aquinas, divided into three parts, each dealing with aspects of God's presence. It serves as an extended meditation on the presence of God, addressing key theological and philosophical questions. In the video, it is introduced as the framework for Aquinas's exploration of God's existence.

💡Five Ways

The 'Five Ways' refer to Aquinas’s famous five proofs for the existence of God, presented as rational arguments based on natural observations. They demonstrate how human beings can know God's existence through experience and reasoning. These include arguments based on motion, causality, contingency, degrees of perfection, and design in nature.

💡Natural Knowledge of God

Natural knowledge of God refers to the ability to know God's existence through human reason and observation of the natural world, without the need for divine revelation or scripture. Aquinas argues that this knowledge is innate to humans, though it can be developed through philosophical inquiry. It contrasts with knowledge obtained by faith.

💡First Mover

The 'First Mover' is one of Aquinas's Five Ways, where he argues that everything in motion must have been set in motion by something else, ultimately requiring a First Mover who is unmoved, and that this is God. It relates to the concept of cause and effect in nature, where the origin of motion must be explained.

💡Uncaused Cause

The 'Uncaused Cause' is another of Aquinas’s proofs for God’s existence, which argues that every effect must have a cause. There must be an original, uncaused cause that set everything into motion. Aquinas posits that God is this uncaused cause, responsible for the chain of causality observed in the natural world.

💡Contingent Beings

Contingent beings are those that exist but do not necessarily have to exist, meaning their existence is not necessary. Aquinas’s third way argues that since contingent beings exist, there must be something that exists necessarily (i.e., God) to explain why anything exists at all. This is central to his proof from contingency.

💡Perfection

Perfection in Aquinas’s argument refers to the degrees of goodness or perfection observed in the world, where some things are better or more perfect than others. The existence of these gradations leads to the conclusion that there must be a supreme source of perfection—God, the perfect being from whom all perfection derives.

💡Supreme Intelligence

The 'Supreme Intelligence' is the conclusion of Aquinas’s fifth way, where he argues that non-intelligent beings, such as plants and animals, act toward specific ends in a purposeful way. This suggests they are directed by a higher intelligence, which Aquinas identifies as God, who orders all things in nature.

💡Romans 1:20

Romans 1:20 is a Bible verse cited in the video, which states that God’s existence can be known through the observation of the natural world. Aquinas uses this passage to support the claim that knowledge of God is not limited to divine revelation but is also accessible through natural reason.

💡Natural Theology

Natural theology refers to the study of God based on reason and observation of the natural world, rather than through divine revelation. Aquinas's Five Ways are key examples of natural theology, where he attempts to prove God's existence through rational arguments, appealing to human reason and experience.

Highlights

Thomas Aquinas's 'Summa Theologiae' has three main parts, each dealing with a different aspect of God's presence.

The first part focuses on God's presence in creation.

The second part addresses God's presence by grace in the souls of the just.

The third part discusses God's presence in Christ and His mystical body, the Church.

Aquinas explores one of the greatest questions: Does God exist?

Aquinas's famous 'Five Ways' are presented as five proofs for the existence of God.

Aquinas taught that human beings have a natural knowledge of God through their natural reason or human intelligence.

Romans 1:20 and the Book of Wisdom confirm that God's existence is known to all through the beauty of the natural world.

Aquinas found that ancient pagan philosophers, without reading the Bible, had serious arguments for God's existence.

Aquinas emphasizes that the natural knowledge of God can develop with intellectual effort but is not always explicit or undeniable.

The inference from the order of the world to the existence of God is a fundamental way humans reason.

The 'Five Ways' argue that visible effects in the world imply an invisible cause, such as God's existence.

Aquinas's first way discusses motion and the need for an unmoved mover.

The second way explains the necessity of a first cause for the order of causality in the world.

The fifth way highlights the purposeful actions of unintelligent beings in nature, implying a higher intelligence guiding them.

Transcripts

Thomas Aquinas's famous work called the Summa Theologiae has three main parts.

The first part deals with the presence of God in creation.

The second part deals with the presence of God by grace in the souls of the just.

The third part deals with the presence of God in Christ and in His mystical body, the

Church.

The whole thing is really an extended meditation on the presence of God, but one of the greatest

questions of all times is whether God exists, and Thomas takes the question head on with

his famous five ways or five proofs for the existence of God.

In this episode, we will give a brief sketch of the five ways, but let us first ask how

human beings can know the existence of God.

One way to know God's existence is by taking it on faith from what the Bible says.

But Thomas is well aware that the Bible itself tells us that there's another way to know

the existence of God.

In Romans chapter one, verse 20, St. Paul tells us that the existence of God is known

to everyone, at least in a general and confused sort of way from the beauty and goodness of

the natural world.

Romans chapter one, verse 20 is a quick summary of a longer passage in the Book of Wisdom,

chapter 13, verses one to nine.

The two passages tell us to expect to find human beings who have never even read the

Bible, but know that God exists just from their experience and rational reflection upon

the natural world.

Now, when Aquinas turned to the writings of ancient pagan philosophers, he found exactly

that.

He found people who had never read the Bible, but who had given serious arguments for the

existence of God.

The writings of ancient pagan philosophers confirmed the biblical teaching that it is

possible for human beings to know the existence of God without ever even having read the Bible.

For both of these reasons, Aquinas taught that human beings have a natural knowledge

of God, or to put it another way, that we can know the existence of God by using our

natural reason or human intelligence.

That is the kind of knowledge we're exploring here, our natural knowledge of God.

Now, Aquinas did not say that our natural knowledge of God was always explicit, clear,

or easy to come by.

He did not affirm that the existence of God was undeniable.

Rather, he thought of the natural knowledge of God as falling on a spectrum of cognitive

development.

Everyone has a common and confused knowledge of God's existence, but like any other form

of knowledge, this common and confused knowledge of God is open to development for those who

have the time, interest, and intellectual gifts for developing it.

Thomas also realized that it was hard to develop our natural knowledge of God, and many factors

stand in the way.

Depending on cultural circumstances, people will develop it more or less, but generally

not to its fullest perfection.

But, he says, a few people after a long time, and still with some errors mixed in, will develop

their natural knowledge of God to such an extent that they can offer philosophically

rigorous proofs for the existence of God and answer all objections to those proofs with

great dialectical skill.

This is the task he takes up in the famous passage on the five ways and in other more

extensive writings of his on the topic.

So how exactly do we know the existence of God?

The basic principle behind the five ways is that we know the existence of God from our

experience of the world of nature and looking for an ultimate explanation of it.

We use the same kind of reasoning that we use when we know the existence of any invisible

cause from visible effects.

For example, if I'm driving down the freeway and see a billowing cloud of smoke coming

up from the horizon, I can infer there must be a fire, even if I do not see the fire, even

if it's blocked from my view.

The fire is invisible, but the smoke it produces is not, and I know the existence of the invisible

cause from the visible effect.

Or similarly, if I wake up one morning with a sore throat, I infer that I have some kind

of infection or virus.

I do not see the infection or the virus.

The cause of the sore throat is invisible, but I know that it's there by reasoning from

the experience of the symptoms.

So it is with our knowledge of God.

What we see or experience around us is the natural world.

God is invisible.

We don't see Him, but from what we do see and experience of the natural world, we can

infer that something must be behind it all.

Something is responsible for the greatness, the beauty, the order of the world.

Aquinas thought that this inference from the order of the world to the existence of something

responsible for the order of the world was so fundamental that nearly all human beings

reason this way.

But he also realized that this inference or argument was something like a seed.

The seed can develop and grow through study and the application of the mind to the many

philosophical issues involved in making the inference, but the seed can also be crushed

by attachment to sin, willful self-denial, false philosophies, and other adverse conditions

that ruin it.

So we're not committed to saying that agnosticism and atheism are impossible.

They might even become prevalent in some societies, but we are committed to saying that natural

theology is possible for human beings.

Thomas Aquinas is an example of someone who developed this natural knowledge of God to

an extremely high degree.

What he did was take the general argument from the order of nature and think it through

along much more specific lines.

To spell this out let us give a sketch of each of the five ways.

In the first way we start with our experience of the order in the motion or change of things

around us in nature, and careful study of what motion and change are leads us to conclude

that there must be a first mover or unmoved mover or an ultimate source of change in things.

In the second way we start with our experience of an order of cause and effect in things

around us.

When we reflect carefully on what causality is, we learn that in order for there to be

causes at work, there must be a first cause or uncaused cause.

In the third way we start by considering the order of contingent beings, things that exist

but do not have to exist.

When we reflect on things that exist but do not have to exist, we naturally ask why do

they exist?

This leads to the conclusion that there must be a source of the very existence of contingent

beings and the source cannot not exist.

The source simply is.

In the fourth way we look at how things around us exist in grades of perfection and the grades

of perfection lead to the conclusion that there must be a perfect being, the source

of being in everything else.

And finally, in the fifth way we find in nature that things without intelligence act for the

sake of ends.

Honeybees work to produce honey even though they do not have intelligence properly speaking.

Things without intelligence cannot work for the sake of an end unless a higher intelligence

is directing them.

This leads us to conclude that there must be a supreme mind or intelligence behind it

all.

Now, what I've given here are just sketches of the arguments, and one can spend a lifetime

considering all the issues surrounding them, but even the sketches give us a way to begin

meditating on the presence of God and the world around us.

God is present in things, moving them, causing them, giving them being and directing the

course

of everything.