I likely will be moving on.  My own confusion comes from the fact that all I've said here is put into my own words what you said here:

I agree.

The ultimate substance of which a dog (or of which anything else) is composed is eternal. It is only that substance's expression as a particular "dog" or "tree" or "man," etc., that has a beginning and an end.

According to the axioms used in this thread, a thing can no more be "created" ex nihilo than it can pop into existence ex nihilo. All things are composed of the eternal, uncaused substance.

Your argument appears to have come to because a dog is composed of X, the dog is X.  That would be silly, but it appears to be your argument, even though it wasn't earlier- earlier you made the very point that I am making.  I asked at that time to delay the issue because I planned on making the very same point on my own, and that is what my latest statements are doing.

So, to take your mathematical analogy, we might say that X=14+17+11.  Using other arguments, we decide that this means that X=42.  So now we begin looking around for X.  We come across one of the real things, '14.'  We ask, "Is this 42?"  We say, no.  We conclude then, ok, this is not X/42.  However true this is, it does not exclude '14's reality or alter its fundamental relationship with the set,  42/X.

To illustrate where I think you may be going wrong. The human body is the sum of all the cells in the human body. The cells are real things but are all contingent on the body. The body is also a real thing.

How are the cells "contingent" on the body? The cells ARE the body. Remove all the cells from a human body and what remains?

"Exactly."

You say exactly but then go on to contradict yourself.

"X cannot be included in the set of things of which it is the sum."

And no one says it is.  X just serves as a place holder.

14+17+11=x

The x is merely a variable.  Truly, this is simple algebra.

Given the above statement, it follows that 14 itself is not x, nor is 17, nor is 11.  If you came across anyone of these figures on their own but with that given, you'd know that you didn't have x.

"If X is the sum of the set [14, 17, 11] then X cannot be in that set. In other words it is false that X is the sum of the set [14, 17, 11, X]."

X is merely the name of the set.

It really can't be any plainer than that.  You merely repeat your latest assertion and completely contradict your own personal argument.

If that is not so, please reconcile your latest remarks with your previous statement that I quoted.  Perhaps that will lead to the root of the confusion.  As it is, all I did was merely state your own argument.

"I beg to differ."

You can beg all you want.  You're playing a silly semantic game that contradicts your own argument which I've cited.

Please do as I requested and explain to me how your own argument which I cited is free from the same criticism you now offer here.

You are being extremely irrational, wavering between equivocations as it suits you.  On the one hand, it was established at the beginning that the use of the term 'X' was merely a nuetral place holder.  On the other hand, you move from the use of the term as an abstraction to whatever substance it signifies.

So, if we were saying, "The universe is the sum of all that is real" at first you would understand that the word 'universe' is merely a symbol representing something else but then as it suits your fancy, the fact that the symbol itself is included in the abstraction you challenge the argument.  Or do you think that the symbol 'universe' really is the universe?

The symbol 'X' is only that, a symbol.  It signifies the sum of all that is real.  

I ask you again to justify your own argument, which I have already cited.

Cogito --

How are the cells "contingent" on the body? The cells ARE the body. Remove all the cells from a human body and what remains?

The body makes cells.  With the exception of your brain cells, there is probably not a single cell in your body that you were born with.  So that cell in your hand was completely contingent on your body.   The hand cell would be part of the set that is you, but you are also a real thing.

We're really talking about different levels here.

God is real but He includes everything else, so He is the sum of all that is real.  Just as the body is the sum of all real cells but the body has reality as well.  

Perhaps it would be clearer to say that God is the sum of all that is real that is less than God, and He is also real as the whole.

Or in neutral terminology: X is the sum of all that is real that is less than X.  X may also be real in its totality.

The body makes cells.

Or more accurately, cells make cells.

This puts me in mind of an interesting question in aesthetics. What is a work of art? Is it the idea? Is it the artifact? How much of the Venus de Milo must be removed before we no longer have a "work of art"?

The body is no more than the cells that compose it at any point in time: no cells, no body.

"There is a fundamental substance of which all real things are composed. The sum of this fundamental substance equals the sum of all that is real.

Are we saying the same thing here?"

Seems to me, pretty much.  However, as your question about 'art' suggests, you seem to be prepared to accept something very close to Plato's 'Forms.'  If that is the case, I can re-state my contingency arguments and all will be well.

However, as I indicated, we are moving from the a priori to the a posteriori.

It is an indisputable fact of observation that some real things are contingent.  This particular arrangement of letters that you see on this post are real, but the order is contingent on my active intervention.  If the letters you observe on your computer have any meaning, if that meaning is to be real it is contingent on your agency.  The letters are certainly real, but so to are the meanings they are meant to communicate- but the meaning you then ascribe to them is contingent on your agency, and you have assured me that you are real.

Without our agency, the letters communicate nothing.  Thus, meaning- real?- is contingent.

"I am not at all clear about how my relating that question from the field of aesthetics allows you to infer anything about my beliefs concerning how that question ought to be answered."

Well, we'll let it ride for now, then.  :)

"OK. Then proceed with the remainder of your argument."

Very well, as I indicated, we are moving from the a priori to the a posteriori, and this is where it starts getting into as much into how the world is experienced as how we deduce it 'must be.'  Ie, we might be able to construct a priori alternative possibilities on how the world might behave, but nonetheless, that is not how it behaves.  A truthful statement about the world will be a representation that accurately reflects what is the reality.

So, I said that whatever is contingent cannot be X.  It does not matter if the argument can be made that in fact, in some respect, anything that is real must be in some way noncontingent.  The condition may never exist, yet it is nonetheless a true conditional:  If anything is contingent, it cannot be X, because X is non-contingent.

Now, it so happens that:

K.   I, sntjohnny, am contingent.

There was a time when I was not.  This is a fact I can perceive from my own introspection.  My earliest memory seems to be from about age 5.  There is nothing before that.  If there was a 'me' before that, I do not have any knowledge of that 'me.'  Based on a little research, I can discover more details to corroborate what I already know.  I know when I was born, and I can deduce a 'conception' date from that, and from so interviewing the world around me, learn the general timeframe for when 'I' came to be.

Conclusion 1:  Therefore, I, sntjohnny, am not X.

L.  My existence is not a logical necessity.

I did not have to be.  Even if the X-Substance I am composed of always is, 'I' am not a required expression of X.  X can exist without 'me.'  Indeed, it must, or it would not be X.

M.  I had a beginning that coincided with the contingent movement from when I was not to when I was, and am.

Shorthand for M:

M[shorthand]: I had a cause.

Without that cause(s), I would not be.

I will once again re-iterate that this is a movement from strict a priori postulations to a posteriori statements.  You might be able to argue that it is a logical possibility that I always existed.  *shrug*  It is nonetheless an undeniable fact of reality as I myself have experienced it that there was a time when I was not and that I was caused to be and did not have to be, at all.

Perhaps you have a different experience.  Perhaps you think that in fact you have always existed, that your existence is a logical necessity, that you are not contingent, that you had no cause.  Maybe its even true for you.  :)  My job is not to address your (alleged) reality, but rather my reality, which I directly experience.

Thus, I find that K, L, and M, and conclusion 1, are undeniable facts of my reality.  

Now, at this point in the conversation, it would be up to you to decide if instead of 'sntjohnny' you can plug in your own being.  Are you 'like' me?  Do you experience reality in a way that I described my own experience of reality?  If so, than the argument can continue to hold up to this point.

So, now I wait for comments.