Thomas Aquinas'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. And 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 1, 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. And Romans chapter 1, verse 20, is a quick summary.
of a longer passage in the Book of Wisdom, chapter 13, verses 1 to 9. 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 Thomas 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 in the experience of the natural world, we can infer that something must be behind it all.
Something is responding. 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. And 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 the word 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. And 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 it. 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 have 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 in the world around us. God is present in things, moving them, causing them, giving them being, and directing the course of everything.