The Unmoved Mover (Aquinas's First Way)

An explanation of Aristotle's framework of movement, change, actuality, potentiality, and the argument offered for the existence of an unmoved mover or actuality, and St. Thomas Aquinas's use of this to prove the existence of God.

Sponsors: João Costa Neto, Dakota Jones, Thorin Isaiah Malmgren, Prince Otchere, Mike Samuel, Daniel Helland, Mohammad Azmi Banibaker, Dennis Sexton, Yu Saburi, Mauricino Andrade, Will Roberts, Greg Gauthier, Christian Bay, Joao Sa, Richard Seaton, Edward Jacobson, isenshi, and √2. Thanks for your support!

Information for this video gathered from The Stanford Encyclopedia of Philosophy, The Internet Encyclopedia of Philosophy, The Cambridge Dictionary of Philosophy, The Oxford Dictionary of Philosophy and more!

[Math_oma]

This is good, but there are some important things missing here:

(1) The sort of series of movers that St. Thomas is interested in are those which are essentially ordered (per se), in which the actualization of a potential cannot occur if it were not for the concurrent actualization of this other actualizer. This is why this statement is important: "seeing that subsequent movers move only inasmuch as they are put in motion by the first mover". This has bearing on your premise 5 and _why_ infinite regresses are impossible in such series of movers - it's not some arbitrary thing he's declaring there. The stock example of this is a father begetting a son, who in turn begets another son; the grandfather need not exist for his son to beget another son and so his power to do this is not essentially dependent on his father, so we have here an accidentally ordered series. This is why the example Aquinas picks here illustrates the point, in which a staff, being moved by a hand, moves a stone; the staff only has power insofar as it receives it from the hand (the hand receives power from another etc.) and without the hand, the staff doesn't do much of anything. So the hand is moving the stone, using the staff instrumentally. Of course the hand is also used instrumentally, so this series could be backed up further. It is in such a series of derived powers that there cannot be an infinite regress; if there could be such a thing, there would be no observable change because actualizers never derive power from anything; we'd have an infinite series of instruments which are not the instruments of anything. This is manifestly contrary to experience, so we conclude that infinite regresses in such essentially ordered series are impossible. From this, the conclusion of an unactualized actualizer/unmoved mover/ Prime Mover follows, since the series is finite, and that which terminates it cannot itself be actualized, otherwise it wouldn't truly be first.

(2) The inference to pure actuality takes a few more steps in addition to what's shown here. The inference from unmoved mover to pure actuality is made in the next question (Part 1, Question 3, Article 1) through the absolute priority of act to potency; there being potencies in the unactualized actualizer would violate this asymmetry between actuality and potentiality and so there must not be any potencies in this unactualized actualizer/ Prime Mover. Although St. Thomas ends these proofs with some variant of "and this is what everyone understands to be God", the case is made in a cumulative manner in the first part of the Summa Theologiae, building upon what is established in this article.

[AntiCitizenX]

I am curious what you would think about a simple thought experiment against Aquinas. Imagine two billiard balls moving towards each other. They then collide and move away. An outside observer could then ask "what caused ball X to switch direction (i.e., move)?" The answer is the collision with ball Y. The same observer could then ask "what caused ball Y to switch?" The answer, then, is collision with ball X.

The thought experiment clearly shows that there is no such thing as "action" per se. There is only "interaction." This completely debunks the idea that acts cannot "cause themselves, " because we clearly have a closed system where both "motions" were literally caused by the other. Barring that, we could further deduce that an "unmoved mover" is completely meaningless. It is not possible for X to cause Y without Y also exerting some causal influence upon Y.

[larrywilliams]

Good job, Aquinas! Even someone who has very little education can reason this in their own conciseness.As a little boy, I climbed trees and felt the motion of the wind.In that seclusion I wondered how it all got here.

[frankied.]

Okay, I feel like there are a couple things wrong with using ancient philosophers as a reasonable source; there were many things they did not understand that we know better now. For example, Aristotle used potential and actuality to build concepts of change, however he did not know about conservation of mass, momentum, or thermodynamics. These are speculations that were never built on solid ground just like how they thought everything was made out of water, ground, and air (or something like that) - now we have an applicable study of chemistry. I would argue to say that a lot of Aristotle's thoughts are outdated (by literally two thousand years) and would be considered pseudo science nowadays or even racist.

[mythologicalmyth]

the comments are more inquisitively interesting....

[matthewfredrickmfkrz]

Exotic forms of ice where you'd think they were potentially cold but since they are formed by pressure are actually hot

[jerometaperman]

The idea of the unmoved mover or prime mover is fine as far as it goes but its problem is that it doesn't go very far at all. There is something to be said about god or whatever being that prime mover but, once you arrive there, you can't really go much further. It tells you nothing about the nature of that prime mover yet folks like Aquinas go from there to this heavily detailed description of a sentient, watchful deity that keeps tabs on us over all the other stuff in the universe, cares about our behavior and is ready to exact unimaginably horrible punishment for behaviors of which it disapproves. On top of that, many of the adherents of this idea feel compelled to go around and tell others that there is something wrong with THEM if they can't understand this. If you don't hop onto this bandwagon, you are flawed and evil. To hell with that.

[sranzuline]

I'll try to turn my brain on in this one:
I think the example of "an industrial robot taking a set of parts and changing them by taking their potential to be a car and actualizing it" and the regress that occurs when the robot came from the rocks (actualized from the rocks' potential to be a robot) and then the rocks was actualized from the potential of the lava to change to rocks does not introduce an infinite regress because rocks are part of the rock cycle. so it is one of the argument's fallacies? the cycles of nature? same thing could be said about the ice, rain, water, water vapor, etc.

[Mxa]

I've got a humble question: how come the Aristotle's unmoved mover can be the god of Bible? It doesn't make sense at all.
From what I read, the unmoved mover inspire the others to move, it doesn't move directly anything, it moves as the final cause of the others movement because it is the Good, and every living thing seeks its own good.
Now, how can an unmoved mover be the efficient cause of the movement of others, the primer cause? If it doesn't move, it can't be the efficient cause.
Also, how come the God of Bible, who talks to many people, who is Jesus and does miracles and so on, can be the unmoved mover? It is clear both, god and Jesus, were moving around on the Middle East a lot!
So, how come the god of Bible can be said to be the unmoved mover?
Thanks.

[Ansatz]

*P3* and *P5* seem troublesome.

*P3) Therefore objects cannot change themselves. They must be changed by some other actuality (since potentiality must be changed by actuality and one thing cannot be both actual and potential.)*

Of course one thing cannot be both actual and potential in the same property, and of course nothing can be caused by mere potential, since potential doesn't actually exist. But one thing can be potential in one property while being actual in a different property, and how can we be sure that actuality in one property cannot cause change in some other property of the same object?

For example, if I strike a match, I move it from the potentiality of being struck to the actuality of being struck, then the match's actuality of being struck moves the match from potentiality of burning to actuality of burning. Further we might imagine there is a whole series of chemical processes within the match to turn it from potentially burning to actually burning, each step being an actuality of one property of the match moving another property to actuality in a chain reaction until actual burning results.

*P5) This chain of actualities cannot be infinite.*

Infinite chains may be hard to imagine, but that doesn't mean we can take it for granted that they are impossible. For example, a train is traditionally pulled by an engine car. The engine pulls the next car, and that car in turn pulls the next. Therefore the question is whether infinite train would even need an engine. It seems that each car could be pulled by the car ahead of it in a never ending sequence of cars, so there is never any need for an engine to ultimately pull the train. The fatal problem with this situation is that no one can ever attempt to build an actual infinite train, so there's no way to determine if such a train could move without an engine. We can only guess, and therefore *P5* is unsupported.

[jolssoni]

Why can't all the potentialities and actualities form a closed system, a circle if you will? Instead of having to conjure up a first mover, which can't really be made sense of unless you're just rationalizing your way into the already chosen endgame of an Omnimax God, you only need to take the existence of the universe as brute.

[mikebowlesmusic]

There is no difference between an infinite regress and an always existing god.

[clarkedavis]

Ontological mathematics describes the Unmoved Mover. Thanks for the video.

[bobbelknut]

But why call this unmovable mover god? In normal day usage, the term god would contain a bunch of assigned properities. Like conscious, omnipotent and merciful etc. Without this religious connotations, the whole word loses its meaning. Allthough Aquinas's considerations seem inherent logical, they just point out that there should be a cause of all motion. No more, and no less.
Tell me if Im wrong but according to this, the big bang also would classifiy as god? Or basically any explanation for the beginning of space and time.

[SuperRichie]

The Unmoved Mover is just Infinite Regress with ... and so god! tacked on at the end.

[brocklanders]

Say what!? Being Atheist is so much more simple.

[Wherrimy]

So it is basically a formulation of the great paradox of why there is something instead of nothing, and a spurious conclusion attached to it. However, I don't buy it. Since we're dealing with a paradox, normal logic won't apply. How is the existence of the unmoved mover any more plausible then the infinite chain of actualities? Besides, according to this description, the 'mover' doesn't have to be sentient or have any volition at all, calling it a 'God' is completely arbitrary.

[LogicAndReason]

"It was magic" is not an explanation. More questions/ no answers.

[vgovger]

Mankind is God, that's how you account for the unmoved mover.

[danielray]

thats basically an analogy to first cause, which is pretty flawed