St. Thomas Aquinas: Existence of God can be proved in five ways.
The First Way: Argument from Motion
Our senses prove that some things are in motion.
Things move when potential motion becomes actual motion.
Only an actual motion can convert a potential motion into an actual motion.
Nothing can be at once in both actuality and potentiality in the same respect (i.e., if both actual and potential, it is actual in one respect and potential in another).
Therefore nothing can move itself.
Therefore each thing in motion is moved by something else.
The sequence of motion cannot extend ad infinitum.
Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God.
The Second Way: Argument from Efficient Causes
We perceive a series of efficient causes of things in the world.
Nothing exists prior to itself.
Therefore nothing [in the world of things we perceive] is the efficient cause of itself.
If a previous efficient cause does not exist, neither does the thing that results (the effect).
Therefore if the first thing in a series does not exist, nothing in the series exists.
If the series of efficient causes extends ad infinitum into the past, for then there would be no things existing now.
That is plainly false (i.e., there are things existing now that came about through efficient causes).
Therefore efficient causes do not extend ad infinitum into the past.
Therefore it is necessary to admit a first efficient cause, to which everyone gives the name of God.
The Third Way: Argument from Possibility and Necessity (Reductio argument)
We find in nature things that are possible to be and not to be, that come into being and go out of being i.e., contingent beings.
Assume that every being is a contingent being.
For each contingent being, there is a time it does not exist.
Therefore it is impossible for these always to exist.
Therefore there could have been a time when no things existed.
Therefore at that time there would have been nothing to bring the currently existing contingent beings into existence.
Therefore, nothing would be in existence now.
We have reached an absurd result from assuming that every being is a contingent being.
Therefore not every being is a contingent being.
Therefore some being exists of its own necessity, and does not receive its existence from another being, but rather causes them. This all men speak of as God.
The Fourth Way: Argument from Gradation of Being
There is a gradation to be found in things: some are better or worse than others.
Predications of degree require reference to the “uttermost” case (e.g., a thing is said to be hotter according as it more nearly resembles that which is hottest).
The maximum in any genus is the cause of all in that genus.
Therefore there must also be something which is to all beings the cause of their being, goodness, and every other perfection; and this we call God.
The Fifth Way: Argument from Design
We see that natural bodies work toward some goal, and do not do so by chance.
Most natural things lack knowledge.
But as an arrow reaches its target because it is directed by an archer, what lacks intelligence achieves goals by being directed by something intelligence.
Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.
There is motion. Things move when potential motion becomes actual motion. Only when potential motion exists ( the possibility to instantiate actual motion ), actual motion can be instantiated.
Each thing beginning to move is moved by a cause. The sequence of motion cannot extend infinitely. Therefore, there must be a first mover, that puts motion in motion which is God.
Thomas Aquinas’ Unmoved Mover – Debunked (Kreeft and Prager Refuted)
In the interest of keeping this video relevant, I’m going to address Kreeft’s specific
rendition of the Unmoved Mover rather than Aquinas’, because, while the two differ
in the language and references that they use, they are nevertheless fundamentally the same.
And so, here’s Kreeft presenting the argument: “The argument starts with the not very startling
observation that things move.
But nothing moves for no reason – something must cause that movement, and whatever caused
that must be caused by something else, and so on.
But this causal chain cannot go backwards forever.
It must have a beginning.
There must be an unmoved mover to begin all the motion in the universe.
A first domino to start the whole chain moving, since mere matter never moves itself.”
Everything that exists is in motion.
Everything in motion is caused to be in motion by something else.
Something must’ve existed without a cause.
We call this first-cause (or unmoved mover) god.
Therefore, god exists.
So, straight from the outset, I want to point out two absolutely devastating flaws.
The first is that even if we accept every premise of Kreeft’s presentation of this
argument, all this would prove is that an Unmoved Mover existed, and that’s it!
Seriously, that’s all it would prove.
It would not prove that this Unmoved Mover still exists, that it’s a being, that it’s
conscious, or that it impregnated a virgin, in order to sacrifice itself to itself so
that it could forgive you for your ancestors’ actions… or in other words, it would not
prove that Kreeft’s very specific interpretation of the Christianity is true.
Of course, the argument is not about proving all those added thing
The second game-ending flaw with this argument, is that premise three – the assertion that
“Something must’ve existed without a cause” - is an obvious case of Special Pleading.
A Special Pleading fallacy occurs when a proponent creates an exception to a rule without adequate
justification, and that is precisely what premise three is doing.
It is literally asserting that premise two – the assertion that “Everything in motion
is caused to be in motion by something else”, applies to absolutely everything except for
the cause of the universe, without adequately justifying why.
In fact, by itself, the argument doesn’t even attempt to substantiate this assertion…
it just makes it.
And this brings us perfectly to the crux of Kreeft’s faulty reasoning… in his attempt
to assert that an Unmoved Mover does indeed exist, he offers two additional faulty arguments.
The first is the assertion that “We now know that all matter – that is the whole
universe – came into existence some 13.7 billion years ago, and it’s been expanding
and cooling ever since.”
Now you might be thinking, “Surely, this assertion is true, isn’t it?
After all, I’ve heard many well-respected scientists saying the same, haven’t I?”
Well, the answer is that, it depends; it depends on what definition of the word ‘universe’
is being used … Allow me to explain.
If we are using the scientific definition of the universe – that being “all matter,
space and time”, then yes, it is accurate to say that the Big Bang was the beginning
of the universe; but if we are using the colloquial definition of the universe – that being
“everything that exists, everything that has existed, and everything that will exist”,
then no, it is inaccurate to say that the Big Bang was the beginning of the universe.
Hence, because Kreeft uses the scientific definition of the universe for the conclusion
of this additional argument, but he uses the colloquial definition of the universe for
the conclusion of his main argument, he therefore commits an Equivocation Fallacy, and hence
his argument is invalid.
And the second faulty argument that Kreeft offers is the assertion that, “Because Einstein’s
general theory of relativity says that all time is relative to matter, and since all
matter began 13.7 billion years ago, so did all time.
So there’s no time before the Big Bang.”
Now you might again be thinking, “Surely, this one is correct, isn’t it?”
But again, you’d be wrong.
It’s a false premise.
To quote Sean Carroll, my all-time favourite Theoretical Physicist, “A lot of Cosmologists
will say there was a beginning, and the problem with this is that the prediction that there
was a beginning, or the understanding that there was a beginning, is based on general
relativity, and we know general relativity is not right.
The reason we know it is not right is, for one thing, it is not compatible with quantum
The reason we know it’s not right is because, for one thing, it […] is not compatible
with Quantum Mechanics […] So basically we have a prediction that the universe began
based on a theory that we have no right to trust.”
And hence, to quote Carroll again, “The correct thing to say about the Big Bang is
not that there was no time before it, but rather that our current understanding of the
laws of physics gives out at that moment in time.”
Or to put this in another way; just as Newton’s Law of Universal Gravitation functions perfectly
when applied to our everyday lives, but fails when applied to celestial bodies; Einstein's
General Theory of Relativity functions perfectly when applied to our everyday lives and celestial
bodies, but it fails when applied to the Big Bang.
Hence, when it comes the question of “What existed before the Big Bang?”
The real answer is “We don’t know”, and to add “therefore god” to the end
of this would be a classic Argument from Ignorance – which, indeed, is unfortunately exactly
what many proponents of the Unmoved Mover do.
Anyhow, to recap, Kreeft’s rendition of Aquinas’ Unmoved Mover is flawed because;
Even if every premise of the argument is accepted, it would not prove that Kreeft’s specific
god exists, and; Premise three commits a Special Pleading Fallacy.
And the two additional arguments that Kreeft offers are flawed because; The first commits
an Equivocation Fallacy when used as a premise in the Kreeft’s main argument, and; The
second is simply false… it’s a False Premise.
As always, thank you kindly for the view, and I’ll to leave you with yet another wonderful
quote from the amazing Sean Carroll: “We use the phrase ‘The Big Bang’ to refer
to that earliest moment in the history of the universe where we don’t understand what
is going on.
It’s a placeholder for our lack of understanding.”