Aquinas' Arguments

What are Aquinas’ Three Ways Arguments?

1. Motion

2. Causation

3. Contingency

What are the Cosmological Arguments?

• Aquinas’ Three Ways

• Kalam Argument

• Descartes’

• Leibniz Principle of Sufficient Reason

Aquinas’ First Way

Motion

We live in a world of motion - things are moving. Movement is caused by ‘movers’. Nothing can move itself, so everything that’s moving must’ve been set into motion by something else.

*Something* must have started the motion in the first place. If it didn’t, then there’d be no first mover, and nothing would be in motion.

But the universe *is* in motion, so there *must* be a first mover, itself unmoved. This is God (the only omnipotent being - necessary for the ‘unmoved’ condition)

Aquinas’ Second Way

Causation (effects have causes)

We find cause and effects in the world. Nothing can be the cause of itself (it’s illogical, it would have to exist to cause itself into existence). So, it must be caused by something else, as there can’t be an infinite regress of causes.

So there *must* be a first causer, itself uncaused, and that must be God

Why can’t there be an infinite regress of causes?

Aquinas’ Second & Third Way. Kalam Argument

It’s absurd/logically impossible. It implies *any* series of events never began, as it started with nothing, and so would’ve regressed forever. But there *must* be a beginning to explain the cause + effect of our universe, otherwise it’s like watching a ball roll across a flat room and arguing nothing touched/kicked it. If so, it must’ve been rolling forever, which is absurd and logically impossible.

Aquinas’ Third Way

Contingency

Aquinas argues there has to be something to prevent an infinite regress of contingency.

If it’s possible for something to not exist, then at some point, it did not exist. We cannot have a world where everything is contingent, because then \[by definition\]

a. it’s possible that that at some point there was nothing in existence

or b. it all could easily have never existed

But there must be at least *one* necessary being to get everything going

Things in the universe exist contingently, but there can’t only be contingent beings because we’d have an infinite regress of contingency and a possibility that nothing might’ve existed. But an infinite regress is impossible (because things *did* begin to exist, so there was never nothing in existence). So there must be at least one necessary being (God).

What is a Necessary Being?

A being that has always existed, will always exist, and cannot not exist. A being that exists by its own nature & doesn’t depend on anything else for existence

What is a Contingent Being?

Things that exist contingently are things that might not have existed

Movers + Potentiality and Actuality States

Aquinas’ 1st Way: Motion

Movement is caused by ‘movers’. A thing can only be reduced from potentiality to actuality by something already in that state of actuality. For example, a curtain has the potentiality of being hot, if it catches on fire. To do so, this shift from potentiality to *actually* catching on fire can only come about if the thing setting it in motion is in a state of actuality itself \[e.g., a candle on fire\]

How can we criticise the Actuality + Potentiality argument?

Aquinas’ 1st Way: Motion

It’s rather outdated. Aquinas was writing in a time before we had the scientific knowledge that we do now. We can criticise Aquinas’ claim that something which causes another thing to change towards a particular state must itself already be in that state, as he uses the state of warmth as an example

Something on fire causes another thing to catch on fire, but only if it itself is on fire. But what about friction? My hand causes my other hand to warm up when I rub them together, yet neither of my hands begin with possession the state in which they cause the other to change to. They both begin in a state of cold and both change to a state of warmth

Doesn’t line up with Aquinas’ claim

Issue with the Nature of God concluded by Aquinas

Aquinas’ 1st/2nd Way: Motion/Causation

We can question the nature of the God being concluded by Aquinas. When considering the chain of causation/motion, it’s easy to think of it temporally \[‘horizontally’\], with each event proceeding and causing the next event. With this, a cause refers to the factor that brought about the effect. The chain of causation is thus one that goes backwards in time, with God, the first cause, at the beginning, starting the whole thing off \[e.g., like a finger knocking over the first of a chain of dominoes\]

If we take the ‘temporal’ interpretation of causation, then the cosmological argument seems to show that a first cause, God, once existed and once created the universe. But it’s crucial to believers that God is still present to act upon the world and still cares about us and the world. This is, after all, the supremely good, all loving God of Abraham, the one described in the Bible. So even if Aquinas’ arguments are sound, we might criticise them for failing to prove the existence of a being who is worthy of worship \[either the God of the Bible or of philosophers\].

It is very possible to imagine a first cause which doesn’t have some of the essential properties of God, and which may not be personal or benevolent or omniscient.

Do Aquinas’ Arguments Rest on Contradiction?

Aquinas’ 1st/2nd Way: Motion/Causation

At first sight, the first and second ways appear to rest on a contradiction. On the one hand, Aquinas says that everything must have a cause and nothing can cause itself, but then he concludes that something must exist that can be the cause of itself, namely God. So, his original assumption \[nothing can cause itself\] is contradicted by the conclusion \[something must exist that can cause itself - God\]

How can we defend against the argument Aquinas’ argument is a contradiction?

Aquinas’ 1st/2nd Way: Motion/Causation rests on contradiction

We can defend by arguing that there has to be at least one exception to the rule ‘nothing can be the cause of itself’. If there were no such exception, then the universe would have no cause and would never come to exist, which we know is not the case as the universe *does* exist. But if there is an exception, the first cause, then it must be something without a cause - an ‘unmoved mover’. When we’re talking about God, we’re dealing with a being unlike anything else, who has a special form of existence and transcends us

How can the defence against Aquinas’ argument being a contradiction be criticised?

Aquinas’ 1st/2nd Way: Motion/Causation

If we allow God to be the exception, why can we not just as well make the universal itself the exception? We could then argue that nothing which occurs in the universe is its own cause, but the universe itself *can* be its own cause. The existence of te universe requires no further explanation: it simply is. This rules out the need to posit God, which only adds extra complexities