Unmoved Mover: Simplicity

There is no composition in God (SCG, I, 18)—Modified

Argument 1:

• Anything composed is something one that is made of many different things (e.g. human person with arms)
• Since many different things introduce unity into a composed thing by being united, the composed thing did not exist prior to being united
• Yet, God is eternal and did not come to exist
• Therefore, there is no composition in God

Argument 2:

• Every composite is subsequent to its components
• But, God is not subsequent to anything
• He is eternal and did not come to exist
• Therefore, God is not a composite

Simplicity

Unmoved Mover: Pure Actuality

There is no [substantial] potentiality in God (SCG, I, 16) – Modified

• Anything that is potentially another thing must proceed from not being that thing to being that thing
• God did not come to be nor can he ever cease to be; He is eternal.
• Therefore there must be no potentiality in God.

There is no accidental potentiality in God

• Anything with accidents is divisible
• God is not divisible
• If He were, then God would depend upon the motion of his dividends
• Therefore, God has no accidents and cannot be in potency to them.

Pure Actuality

Unmoved Mover: Eternity

God is eternal (SCG, I, 15)

• Movement and change precede anything that comes to exist or ceases to exist
• Nothing precedes God
• He is First Cause or Unmoved Mover
• Therefore, God is eternal
• (i.e. there is no beginning or end to Him)

Eternity

Unmoved Mover: Can Something Move Itself?

Let me now repeat the argument for the Unmoved Mover. There are at least some movers that are moved by other movers. There cannot be an infinite series of moved movers. Therefore there must be a first. Either this first mover is moved or it isn’t. It is self-contradictory to posit a first moved mover since it wouldn’t be a first mover. Therefore, there must be some First Unmoved Mover, which we will call God. 

In order to begin the argument, I will deny the conclusion [the first premise] and follow its implications to their [sic] logical conclusions in order to prove for my argument by reductio ad absurdum, which, according to the Internet Encyclopedia of Philosophy, is “a mode of argumentation that seeks to establish a contention by deriving an absurdity from its denial, thus arguing that a thesis must be accepted because its rejection would be untenable” (IEP). 

Here is the argument proving that there is nothing that is moved by itself: if there is some thing which is moved by itself, it must not be moved by any of its parts or at least depend upon the motion of its parts in order to be moved. Otherwise, it would depend upon the motion of other things in order to be moved. For instance, the motion of an animal depends upon the motion of its foot in order to move.

However, since all things that are moved are divisible and have parts [(Physics, VI, 4)], a thing which is moved by itself must have parts. Therefore, either that thing does not depend upon the motion of its parts in order to be moved, or it does. If it does not, then it must be possible that the thing can move while a single part remains at rest, since the thing need not move along with its part if it is moved by itself. But if such were the case, then the whole could not move in unity as a whole, since the other part that moved along with the whole moved without the other part that remained at rest. Therefore, the whole cannot move by itself and through itself if it moved by itself and had parts. 

Therefore, that which is moved by itself must depend upon the motion of its parts in order to be moved. But anything that depends upon the motion of its parts is moved by something else. Therefore, there is nothing that is moved by itself [(Physics, VII)]

Aristotle. Physics. Trans. Richard McKeon. The Basic Works of Aristotle. New York: Random House, 
           1941. Print