Did Aquinas Prove That God Exists?

[Left Coast]

St. Thomas Aquinas was a 13th century Italian priest and theologian. He was the first Christian to write a formal, comprehensive systematic theology and he synthesized Aristotle and Christianity (which was quite controversial since Christianity up to that point had been philosophically neo-Platonist). His work has been highly influential throughout Western Christianity on both theological and moral thought. Basically, he was a big deal.

One of the other reasons he was a big deal is because he developed 5 "ways," or arguments, for God's existence. I thought we would walk through them here. Starting with the First Way:

The existence of God can be proved in five ways.

The first and more manifest way is the argument from motion. It is certain, and evident to our senses, that in the world some things are in motion. Now whatever is in motion is put in motion by another, for nothing can be in motion except it is in potentiality to that towards which it is in motion; whereas a thing moves inasmuch as it is in act. For motion is nothing else than the reduction of something from potentiality to actuality. But nothing can be reduced from potentiality to actuality, except by something in a state of actuality. Thus that which is actually hot, as fire, makes wood, which is potentially hot, to be actually hot, and thereby moves and changes it. Now it is not possible that the same thing should be at once in actuality and potentiality in the same respect, but only in different respects. For what is actually hot cannot simultaneously be potentially hot; but it is simultaneously potentially cold. It is therefore impossible that in the same respect and in the same way a thing should be both mover and moved, i.e. that it should move itself. Therefore, whatever is in motion must be put in motion by another. If that by which it is put in motion be itself put in motion, then this also must needs be put in motion by another, and that by another again. But this cannot go on to infinity, because then there would be no first mover, and, consequently, no other mover; seeing that subsequent movers move only inasmuch as they are put in motion by the first mover; as the staff moves only because it is put in motion by the hand. Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God.

What do you think? Does this prove God exists? Are there any flaws in this argument?

 

[SalixIncendium]

What do you think? Does this prove God exists? Are there any flaws in this argument?

I don't think so. As I read, the question came to mind, "What put God into motion?"

 

[Left Coast]

I don't think so. As I read, the question came to mind, "What put God in motion?"

Aquinas responds to this by saying, "But this cannot go on to infinity, because then there would be no first mover, and, consequently, no other mover; seeing that subsequent movers move only inasmuch as they are put in motion by the first mover; as the staff moves only because it is put in motion by the hand. Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God."

What do you think? Did there have to be a first mover at some point?

 

[SalixIncendium]

Aquinas responds to this by saying, "But this cannot go on to infinity, because then there would be no first mover, and, consequently, no other mover; seeing that subsequent movers move only inasmuch as they are put in motion by the first mover; as the staff moves only because it is put in motion by the hand. Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God."

What do you think? Did there have to be a first mover at some point?

The argument assumes time is linear, so in that respect, I can see how one would come to a conclusion that there would have to be a first mover. However, the argument falls apart with an assumption that time is cyclical...and even more so if time doesn't exist outside of anything besides our perspective.

 

[Left Coast]

The argument assumes time is linear, so in that respect, I can see how one would come to a conclusion that there would have to be a first mover. However, the argument falls apart with an assumption that time is cyclical...and even more so if time doesn't exist outside of anything besides our perspective.

Can you explain that? What would it mean for time to be cyclical?

Per modern physics, time and space are tied at the hip, so to speak - so where space doesn't exist, time wouldnt either, at least not as we understand it. Tom didn't have the benefit of modern physics, but if we steelman his argument, we might say spacetime had to originate at some point.

 

[Polymath257]

One thing to remember is that Aquinas was working with Aristotelian physics. In that, motion (velocity) required a force. But, since Newton, we have come to realize that it isn't motion that requires the force, but a *change* in motion (acceleration) that requires the force.

What is more, Aristotelian physics required *any* sort of change (whether in position or not) to be produced by a force. Once again, that is no longer considered a valid view of how the universe works.

So, at the first, I would challenge the assumption that all all motion is produced by an interaction with another moving object. In other words, he is using the wrong physics.

Next, I would challenge the assumption that an infinite regress is impossible. Whenever such a possibility comes up, there is the question of 'then how did we get here?' Even William Craig uses this objection. But that is a fundamental misunderstanding of the infinite. This would be a valid objection if there was a *start*, then an infinite amount of time, and then we get to today. But the whole point of the infinite regress is that there is no start. Nonetheless, between any two events there is only a finite amount of time. So the issue is NOT whether we can get here from a starting point, but just can we get here from some point in the past. And *that* only requires a finite amount of time.

Next, I would challenge the idea that an 'unmoved mover' would have to be unique. There is nothing in the argument that says there would only be a single unmoved mover. There is no logical reason that there could not be thousands.

Finally, I would challenge the assumption that an unmoved mover would necessarily have the sort of consciousness required to justly label it 'God'. Certainly, no argument is given showing that an unmoved mover must have a *plan*. So, while 'everybody understands it', there is no good reason to identify such a thing with God.

 

[Polymath257]

Aquinas responds to this by saying, "But this cannot go on to infinity, because then there would be no first mover, and, consequently, no other mover; seeing that subsequent movers move only inasmuch as they are put in motion by the first mover; as the staff moves only because it is put in motion by the hand. Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God."

What do you think? Did there have to be a first mover at some point?

No. the argument only shows that things are always moving: each thing is moved by something before, on back infinitely.

Once again, there is no logical contradiction there. It is an assumption that there needs to be a first mover in order to get everything moving. But that fails if everything is always in motion.

 

[Polymath257]

Can you explain that? What would it mean for time to be cyclical?

Per modern physics, time and space are tied at the hip, so to speak - so where space doesn't exist, time wouldnt either, at least not as we understand it. Tom didn't have the benefit of modern physics, but if we steelman his argument, we might say spacetime had to originate at some point.

Even the *equations* of modern physics allow for a cyclical universe: essentially a time dimension that is circular. There are other notions involving causality that seem to point away from this possibility, but it is certainly a *logical* possibility.

 

[GoodbyeDave]

The argument is actually taken from Aristotle. It's quite a good one, if you believe that every event has a cause. An infinite series of events doesn't provide an escape, because of increasing entropy — the universe will eventually "run down", so an infinitely old universe would have run down an infinite time ago. The obvious escape is to assume an uncaused first event but that is, obviously, a rejection of the enterprise of science — if you let in one uncaused event, you have no right to deny the possibility of others. Naturally, those of us who take physics with a pinch of salt will be untroubled by that. The first cause cannot be a material event, because that would also demand a material cause, so if the argument is accepted, the cause must be a mind.

Unfortunately for Aquinas, the argument is of no use to Christianity.It only claims a non-physical cause for the universe. There's no reason why that cause should be a single entity, let alone the Christian God.

 

[Revoltingest]

I remember Aquinas from an undergrad symbolic logic course eons ago.
His arguments were sort of a gold standard for illustrating logical errors.

 

[Left Coast]

One thing to remember is that Aquinas was working with Aristotelian physics. In that, motion (velocity) required a force. But, since Newton, we have come to realize that it isn't motion that requires the force, but a *change* in motion (acceleration) that requires the force.

What is more, Aristotelian physics required *any* sort of change (whether in position or not) to be produced by a force. Once again, that is no longer considered a valid view of how the universe works.

Thank you for this! Wouldn't being "put into motion" be a change in motion, though?

Next, I would challenge the assumption that an infinite regress is impossible. Whenever such a possibility comes up, there is the question of 'then how did we get here?' Even William Craig uses this objection. But that is a fundamental misunderstanding of the infinite. This would be a valid objection if there was a *start*, then an infinite amount of time, and then we get to today. But the whole point of the infinite regress is that there is no start. Nonetheless, between any two events there is only a finite amount of time. So the issue is NOT whether we can get here from a starting point, but just can we get here from some point in the past. And *that* only requires a finite amount of time.

This reminds me of the paradox (I forget what it's called) where to get from some point A and point B, one has to go half the distance. Then when one goes half the distance, one has to go half of the remaining distance. And so on. Which, constructed that way, would make it impossible to get from point A time B. Yet we know getting from point A to B is possible. Dealing with infinites involves weird paradoxes when considered a priori, but when applied to the real world the paradoxes are resolved.

Next, I would challenge the idea that an 'unmoved mover' would have to be unique. There is nothing in the argument that says there would only be a single unmoved mover. There is no logical reason that there could not be thousands.

Good point! I hadn't thought of this.

Finally, I would challenge the assumption that an unmoved mover would necessarily have the sort of consciousness required to justly label it 'God'. Certainly, no argument is given showing that an unmoved mover must have a *plan*. So, while 'everybody understands it', there is no good reason to identify such a thing with God.

Agreed. Aquinas seems to be massively begging the question here.

 

[epronovost]

To make a very, very long story short, not Aquinas 5 arguments for the existence of God are actually fairly bad when one takes into account the progress of science in physics and the advancement in philosophy though they were very solid arguments in 13th century Europe.

The argument for the unmoved mover, first cause and contingency are all flawed because they are basically begging the question and fall prey to the outworld paradox. Even if they were accepted, it does not follow logically that the result of such a thing could be called a God by any human being and could actually be used to support some form of deism or pantheism with an unpersonnal deity. It's even possible to conceive with such argument that the "God" proved by it no longer exist.

The argument from degree falls prey to the concept of relativity and the impossibility to prove the existence of that sort of platonic concept.

The teleological argument is probably the weakest of them all as it assume it's conclusion in the premise of the argument from the get go. It's the one that shows it's age the most.

 

[Twilight Hue]

St. Thomas Aquinas was a 13th century Italian priest and theologian. He was the first Christian to write a formal, comprehensive systematic theology and he synthesized Aristotle and Christianity (which was quite controversial since Christianity up to that point had been philosophically neo-Platonist). His work has been highly influential throughout Western Christianity on both theological and moral thought. Basically, he was a big deal.

One of the other reasons he was a big deal is because he developed 5 "ways," or arguments, for God's existence. I thought we would walk through them here. Starting with the First Way:



What do you think? Does this prove God exists? Are there any flaws in this argument?

Assuming he's correct for sake of argument, that means that God would have been dead a long time ago given a 'first' cause would have ceased to exist.

 

[SalixIncendium]

Can you explain that? What would it mean for time to be cyclical?

Per modern physics, time and space are tied at the hip, so to speak - so where space doesn't exist, time wouldnt either, at least not as we understand it. Tom didn't have the benefit of modern physics, but if we steelman his argument, we might say spacetime had to originate at some point.

Even the *equations* of modern physics allow for a cyclical universe: essentially a time dimension that is circular. There are other notions involving causality that seem to point away from this possibility, but it is certainly a *logical* possibility.

Thanks for explaining this, @Polymath257. Probably means more coming from a mathematician than it does from me.

Here's a bit more on the cyclical universe theory...

The cyclic universe theory is a model of cosmic evolution according to which the universe undergoes endless cycles of expansion and cooling, each beginning with a “big bang” and ending in a “big crunch”. The theory is based on three underlying notions: First, the big bang is not the beginning of space or time, but rather a moment when gravitational energy and other forms of energy are transformed into new matter and radiation and a new period of expansion and cooling begins. Second, the bangs have occurred periodically in the past and will continue periodically in the future, repeating perhaps once every 1012 (10 to the 12th power) years. Third, the sequence of events that set the large-scale structure of the universe that we observe today took place during a long period of slow contraction before the bang; and the events that will occur over the next 1012 (10 to the 12th power) years will set the large-scale structure for the cycle to come. Although the cyclic model differs radically from the conventional big bang–inflationary picture in terms of the physical processes that shape the universe and the whole outlook on cosmic history, both theories match all current observations with the same degree of precision. However, the two pictures differ in their predictions of primordial gravitational waves and the fine-scale statistical distribution of matter; experiments over the next decade will test these predictions and determine which picture survives.

Cyclic universe theory - AccessScience from McGraw-Hill Education

_______________________________________________________________


The idea of time being cyclical isn't a new one. The concept goes all the way back a few thousand years to the Vedas. According to this, a full cycle of time is four Yugas, the Satya Yuga, the Treta Yuga, the Dwapara Yuga, and the Kali Yuga.

Yuga - Wikipedia

This is the long count system:

There is also a short count system introduced by Sri Yukteswar that takes place in a cycle of 24,000 years:

This video describes both count systems:

 

[Terry Sampson]

Once again, there is no logical contradiction there. It is an assumption that there needs to be a first mover in order to get everything moving. But that fails if everything is always in motion.

Intriguing how "Fear of Infinite Regress" affects the mind.
IMO, the notion of "Cyclical Time" is just an attempt to avoid the same fear.
Me? "Time" is an abstract noun. As such, it has no beginning or end that isn't imposed on it by humans.

 

[Unveiled Artist]

St. Thomas Aquinas was a 13th century Italian priest and theologian. He was the first Christian to write a formal, comprehensive systematic theology and he synthesized Aristotle and Christianity (which was quite controversial since Christianity up to that point had been philosophically neo-Platonist). His work has been highly influential throughout Western Christianity on both theological and moral thought. Basically, he was a big deal.

One of the other reasons he was a big deal is because he developed 5 "ways," or arguments, for God's existence. I thought we would walk through them here. Starting with the First Way:



What do you think? Does this prove God exists? Are there any flaws in this argument?

These are all educated guesses or one's best assumptions. People can believe their assumptions and confirm it by their experiences but these things don't prove god (or a mover) exists. It just proves people find "what makes sense" to them as real and treat it as such.

 

[nPeace]

St. Thomas Aquinas was a 13th century Italian priest and theologian. He was the first Christian to write a formal, comprehensive systematic theology and he synthesized Aristotle and Christianity (which was quite controversial since Christianity up to that point had been philosophically neo-Platonist). His work has been highly influential throughout Western Christianity on both theological and moral thought. Basically, he was a big deal.

One of the other reasons he was a big deal is because he developed 5 "ways," or arguments, for God's existence. I thought we would walk through them here. Starting with the First Way:



What do you think? Does this prove God exists? Are there any flaws in this argument?

That's a long explanation.
It's a logical argument, imo, and if it is what we generally observe, would be reasonable to accept, as an argument for a mover.

 

[nPeace]

Assuming he's correct for sake of argument, that means that God would have been dead a long time ago given a 'first' cause would have ceased to exist.

That's covered by his third argument - The Argument from Contingency.

 

[QuestioningMind]

Aquinas responds to this by saying, "But this cannot go on to infinity, because then there would be no first mover, and, consequently, no other mover; seeing that subsequent movers move only inasmuch as they are put in motion by the first mover; as the staff moves only because it is put in motion by the hand. Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God."

What do you think? Did there have to be a first mover at some point?

If movement is eternal then there is no need for a 'first mover'.

 

[shunyadragon]

No, because these apologetic arguments require assumptions that God exists, which makes them 'begging the question.'