The Unmoved Mover and Pure Act
#21
(02-14-2013, 01:28 PM)Scotus Wrote: I was planning to spend the bulk of the time on the First Way of St Thomas Aquinas i.e. the Argument from Motion. However, as I have been working out how to explain each step of the proof there seems (to me at least) in the assertion that the First Mover must be Pure Act.
I prefer to say "Pure Actuality." Viz., He's the most real, actual being there can ever be.
(02-14-2013, 01:28 PM)Scotus Wrote: Certainly, it is clear that this Unmoved Mover is not moved by any other (as we would carry on with our infinite regress), but it does seem to me that there is a jump from proving that there is an Unmoved Mover to stating that this Mover is immovable.
If God is pure actuality, he has no potentiality for movement, so He's both unmoved and immovable (i.e., immutable, unchangeable).

Perhaps the following clarifies another (common) confusion: The principle is: Omne quod movetur ab alio movetur ("Whatever is moved is moved by another."). It is not: "Everything is moved by another."
(02-14-2013, 01:28 PM)Scotus Wrote: In the order of causes this being must be in act in such a way that it is has not been reduced to that act by any other being. But how can we prove that there is no potency in this being, even though these potencies might never be reduced to act?

If we can prove that this Unmoved Mover is Pure Act then it seems that we have failed to prove the existence of God by the evidence of motion in the world.
The world is not an extension of God.
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#22
(02-19-2013, 01:26 AM)Doce Me Wrote: The concepts of causality and non-contradiction are fundamental, and self-evident. 

As is God.  I have actually talked with those who seriously don't believe in causality (Muslims) or non-contradiction (Buddhists).  They are self-evident and axiomatic, but people (indeed, whole civilizations) still reject them.

Quote:But knowing the existence of God requires the evidence of God's creation.

It requires judging that the evidence indeed points to God.  Just as it must be judged that causality is not just a "habit of the mind" as Muslim thinkers deem matters.

Quote: Reason moves from creature to Creator. 

Reason takes judgements and uses logical thinking to reach deeper conclusions.  That God is real is a base-line judgement; that the Christian religion is God's requires some more unpacking.


Quote: I think that St. Thomas' proofs, to those who understand him, guide the reason with certainty through that move.

The reason doesn't need any arguments to be certain of God, "For the invisible things of him, from the creation of the world, are clearly seen, being understood by the things that are made; his eternal power also, and divinity: so that they are inexcusable." (Romans 1:20)  Proofs such as Saint Thomas are similar to arguments for causality or non-contradiction, not QED style demonstrations, but an attempt to draw out what is plainly so in the intransigent mind by way of meditation.

Quote:   (I don't understand them well, but surely Popes who spoke of proofs bringing certainty ranked St. Thomas' proofs very highly among them)

His are quite good as ways for the intransigent soul to meditate on God; but they are not mathematical proofs which cannot be denied.  They are meditations, not equations.  What it sets out to show is obvious and axiomatic.

Quote:The move from creation to the Creator may be a kind of a instantaneous "leap" of judgment for some, but that doesn't show that St. Thomas' methodical reasoning is not proof.

Not for some, that is the standard.  Non-belief in God is, and always has been, a minority report.
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#23
(02-19-2013, 08:15 PM)Parmandur Wrote:
(02-19-2013, 01:26 AM)Doce Me Wrote: The concepts of causality and non-contradiction are fundamental, and self-evident. 

As is God. 

St. Thomas wrote an article arguing that the existence of God is not self-evident. (Objection 2 and its reply show he does not agree with the validity of St. Anselm's "ontological" proof)
"St. Thomas Aquinas, Summa Theologica  I Q2 A1" Wrote:Article 1. Whether the existence of God is self-evident?

Objection 1. It seems that the existence of God is self-evident. Now those things are said to be self-evident to us the knowledge of which is naturally implanted in us, as we can see in regard to first principles. But as Damascene says (De Fide Orth. i, 1,3), "the knowledge of God is naturally implanted in all." Therefore the existence of God is self-evident.

Objection 2. Further, those things are said to be self-evident which are known as soon as the terms are known, which the Philosopher (1 Poster. iii) says is true of the first principles of demonstration. Thus, when the nature of a whole and of a part is known, it is at once recognized that every whole is greater than its part. But as soon as the signification of the word "God" is understood, it is at once seen that God exists. For by this word is signified that thing than which nothing greater can be conceived. But that which exists actually and mentally is greater than that which exists only mentally. Therefore, since as soon as the word "God" is understood it exists mentally, it also follows that it exists actually. Therefore the proposition "God exists" is self-evident.

Objection 3. Further, the existence of truth is self-evident. For whoever denies the existence of truth grants that truth does not exist: and, if truth does not exist, then the proposition "Truth does not exist" is true: and if there is anything true, there must be truth. But God is truth itself: "I am the way, the truth, and the life" (John 14:6) Therefore "God exists" is self-evident.

On the contrary, No one can mentally admit the opposite of what is self-evident; as the Philosopher (Metaph. iv, lect. vi) states concerning the first principles of demonstration. But the opposite of the proposition "God is" can be mentally admitted: "The fool said in his heart, There is no God" (Psalm 52:1). Therefore, that God exists is not self-evident.

I answer that, A thing can be self-evident in either of two ways: on the one hand, self-evident in itself, though not to us; on the other, self-evident in itself, and to us. A proposition is self-evident because the predicate is included in the essence of the subject, as "Man is an animal," for animal is contained in the essence of man. If, therefore the essence of the predicate and subject be known to all, the proposition will be self-evident to all; as is clear with regard to the first principles of demonstration, the terms of which are common things that no one is ignorant of, such as being and non-being, whole and part, and such like. If, however, there are some to whom the essence of the predicate and subject is unknown, the proposition will be self-evident in itself, but not to those who do not know the meaning of the predicate and subject of the proposition. Therefore, it happens, as Boethius says (Hebdom., the title of which is: "Whether all that is, is good"), "that there are some mental concepts self-evident only to the learned, as that incorporeal substances are not in space." Therefore I say that this proposition, "God exists," of itself is self-evident, for the predicate is the same as the subject, because God is His own existence as will be hereafter shown (3, 4).[b] Now because we do not know the essence of God, the proposition is not self-evident to us; but needs to be demonstrated by things that are more known to us, though less known in their nature — namely, by effects.
[/b]
Reply to Objection 1. To know that God exists in a general and confused way is implanted in us by nature, inasmuch as God is man's beatitude. For man naturally desires happiness, and what is naturally desired by man must be naturally known to him. This, however, is not to know absolutely that God exists; just as to know that someone is approaching is not the same as to know that Peter is approaching, even though it is Peter who is approaching; for many there are who imagine that man's perfect good which is happiness, consists in riches, and others in pleasures, and others in something else.

Reply to Objection 2. Perhaps not everyone who hears this word "God" understands it to signify something than which nothing greater can be thought, seeing that some have believed God to be a body. Yet, granted that everyone understands that by this word "God" is signified something than which nothing greater can be thought, nevertheless, it does not therefore follow that he understands that what the word signifies exists actually, but only that it exists mentally. Nor can it be argued that it actually exists, unless it be admitted that there actually exists something than which nothing greater can be thought; and this precisely is not admitted by those who hold that God does not exist.

Reply to Objection 3. The existence of truth in general is self-evident but the existence of a Primal Truth is not self-evident to us.
============
Article 2. Whether it can be demonstrated that God exists?


He says, to the objectors who say it cannot,

On the contrary, The Apostle says: "The invisible things of Him are clearly seen, being understood by the things that are made" (Romans 1:20). But this would not be unless the existence of God could be demonstrated through the things that are made; for the first thing we must know of anything is whether it exists.

Thus he uses the same scriptural quote as you do, but to show that God's existence can be proven (demonstrated). 

I thinks St. Thomas uses his demonstrations to do what you say "judge that the evidence indeed points to God", and
"take judgements and use logical thinking to reach deeper conclusions". But he just doesn't think that God's existence is self-evident or base-line -- because it takes its evidence from God's creatures, and it is possible to take a careful path to God's existence, even if it is common to make a quick leap.

Not all proofs are mathematical.  Not all proofs are understood by everyone. Not all proofs are nothing but syllogisms.  But I'll go with the Popes saying there are proofs that bring certainty, rather than thinking that St. Thomas writings are just meditations (although they are that too). For many St. Thomas' proofs may not be ideal, but I trust the Church and the praise it gives for his teaching.


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#24
Back to the OP question.
(02-18-2013, 07:45 AM)Scotus Wrote:
(02-15-2013, 04:24 AM)TS Aquinas Wrote:
(02-14-2013, 01:28 PM)Scotus Wrote: [..]
Certainly, it is clear that this Unmoved Mover is not moved by any other (as we would carry on with our infinite regress), but it does seem to me that there is a jump from proving that there is an Unmoved Mover to stating that this Mover is immovable. In the order of causes this being must be in act in such a way that it is has not been reduced to that act by any other being. But how can we prove that there is no potency in this being, even though these potencies might never be reduced to act?

This might help from his Conpendium,

"We clearly infer from this that God, who moves all things, must Himself be immovable. If He, being the first mover, were Himself moved, He would have to be moved either by Himself or by another. He cannot be moved by another, for then there would have to be some mover prior to Him, which is against the very idea of a first mover. If He is moved by Himself, this can be conceived in two ways: either that He is mover and moved according to the same respect, or that He is a mover according to one aspect of Him and is moved according to another aspect. The first of these alternatives is ruled out. For everything that is moved is, to that extent, in potency, and whatever moves is in act. Therefore if God is both mover and moved according to the same respect, He has to be in potency and in act according to the same respect, which is impossible. The second alternative is likewise out of the question. If one part were moving and another were moved, there would be no first mover Himself as such, but only by reason of that part of Him which moves. But what is per se is prior to that which is not per se. Hence there cannot be a first mover at all, if this perfection is attributed to a being by reason of a part of that being. Accordingly the first mover must be altogether immovable.
[..]

I've read St Thomas's argument from the Compendium a number of times now and it seems that in the first paragraph quoted shows that the First Mover is not moved but not that He is immovable. Unless, I am missing something? If, so, please show me!
[..]

My comments cover only the part in bold from the Compendium.

St. Thomas (I think) is using a reductio ad absurdum form of argument - arguing that a statement is true by showing that its denial leads to a false (or "absurd") result.  It seems to me that he is simultaneously showing both that God is unmoved, and that He is immovable.

Prove:  "It cannot ever happen that God is moved"  ((Surely this is one meaning for "immovable") (will comment on this again)
Denial:  If is possible that God can be moved (even if it never happens, we can reason from its happening)

Absurd consequences:  (prove the absurdity of God ever being moved)
God would not be the first or unmoved mover (another would move Him)

Therefore: God is immovable.

It is hard to go directly from "Unmoved Mover" to "Immoveable" in my mind - it would be better because "reductio"s are not a strong form of argument.  But this is what I see.

Maybe you will note that "moveable" refers to an inner potency.  But how can a potency exist of which the actualization would lead to the absurd results shown?

I don't know if this helps, causes more confusion, or if I'm missing something.  But it is what I've come up with.
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#25
(02-20-2013, 03:28 AM)Doce Me Wrote: It is hard to go directly from "Unmoved Mover" to "Immoveable" in my mind - it would be better because "reductio"s are not a strong form of argument.  But this is what I see.

Yes, I also find it hard to go from "unmoved" to "immoveable". Prof Edward Feser in his book on St Thomas attempts to prove the "immoveableness" of the First Mover by addressing the question of the actualisation of being. But I cannot pretend to understand what he means.  ???
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#26
(02-21-2013, 01:50 PM)Scotus Wrote:
(02-20-2013, 03:28 AM)Doce Me Wrote: It is hard to go directly from "Unmoved Mover" to "Immoveable" in my mind - it would be better because "reductio"s are not a strong form of argument.  But this is what I see.

Yes, I also find it hard to go from "unmoved" to "immoveable". Prof Edward Feser in his book on St Thomas attempts to prove the "immoveableness" of the First Mover by addressing the question of the actualisation of being. But I cannot pretend to understand what he means.   ???

Motion is a change from potential to actual.  That means that something gains some trait it didn't have before (being in location Y instead of location X, putting a baseball cap on, melting, etc).  In order for the Unmoved Mover to move, there would have to be some lack in Him, something he does not posses.  He would be imperfect, and subject to contingency, and hence could not be the Prime Mover, but some lesser being.
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#27
He can't move because He's already everywhere present.
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#28
(02-21-2013, 03:04 PM)per_passionem_eius Wrote: He can't move because He's already everywhere present.

Exactly; and he cannot grow, because He is always complete.
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#29
In response to the OP, if the first unmoved mover is a composition of Act and Potency, then its being is in potency to that composition, which means it is caused to be. If it is caused to be, then it too must be explained by a prior cause, and then it is not the first cause. Hence, in order to truly explain motion, there will ultimately have to be a being which is pure act.
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#30
(02-21-2013, 01:50 PM)Scotus Wrote:
(02-20-2013, 03:28 AM)Doce Me Wrote: It is hard to go directly from "Unmoved Mover" to "Immoveable" in my mind - it would be better because "reductio"s are not a strong form of argument.  But this is what I see.

Yes, I also find it hard to go from "unmoved" to "immoveable". Prof Edward Feser in his book on St Thomas attempts to prove the "immoveableness" of the First Mover by addressing the question of the actualisation of being. But I cannot pretend to understand what he means.   ???

Scotus, are you beginning to see that St. Thomas (in the words quoted) at least proves THAT God IS immoveable?  In other words, does the "reductio" I gave make sense, even if it doesn't help you go directly from "unmoved" to "immoveable" via an understanding of the nature of potency and act?

However Parmandur, per_passionem_eius, and Papist have helped give a deeper understanding.
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