Miracles cannot exist
1) A miricle, in the layman's sense, must be supernatural(cannot be explained by science), provide a positive outcome(not just some random occurance), must be divine in origin(not a miricle if caused by a ghost or the demon; and must affect change in someway or another.
2) The divine cause of miricles MUST be the Omni-God(any lesser being would not have the same kind of value on the action - intervention by Apollo or Ra does not have the same miricleness as with the Omni-God)
3) If the OG exists then he must be perfect in every respect
4) Thus anything he creates must also be perfect, since an absolute perfect being is not capable of creating something imperfect. .
5) For any given thing or concept, there can be only one perfect form. No two different things can both be entirely perfect.
6) If God modifies the universe, he either made it perfect through his intervention which implies it was imperfect to begin with or he makes it less perfect through his actions.

7) God cannot create imperfection
8) Therefore, God cannot cause miricles.
9) Therefore, since miricles cannot exist without God nor with God, miricles can never occur.


Miracles are defined in a variety of ways. In order to make a coherent argument regarding miracles, we must first establish a concrete definition of it. I suggest we focus on the modern, layman’s conception of a miracle. A miracle is something that must be supernatural, must be divine in origin, and must affect change in some way or another, in a positive way. A miracle must be supernatural because if a miraculous event can be explained by natural phenomenon then it appears that the said event is no longer a miracle. For example, most people would not claim that the boiling of water when heated is a miracle. People also tend to cite instances where science cannot give a logical explanation as instances of miracles. A miracle must be divine in origin because supernatural phenomenon caused by ghosts and demons do not count as miracles, neither would something caused by Ra, the Egyptian sun god. And lastly, a miracle must affect some sort of positive change in the world. Every claimed miracle has always has some affect on the world. A non-event cannot be a miracle since it would be nonsensical to claim that God’s inaction is a miracle.
My next point is that the divine cause of miracles must be the Omni-God. Any lesser being would not have the same miraculous impact. I would also submit that the category of lesser supernatural being would necessarily include the Devil, demons, and other powerful evil beings. Intuition suggests that it is not possible for the Devil to perform miracles. This gets us to the notion that only God could be the cause of miracles and that no other being would be capable of creating a miracle. If they performed the same act it would be wondrous perhaps, but not miraculous.
Now let us assume the existence of God, since to assume otherwise would invalidate the existence of miracles since we just established that they are completely dependent on God. According to our definition of an Omni-God, he must be perfect in every respect. And a perfect being is incapable of creating something that is imperfect. So everything which God creates must be perfect. The idea of perfection seems to suggest that there can be only one perfect “thing” of any sort. Anselm’s ontological argument seems to suppose that logically there can be only one greatest and all perfect being. It seems counter-intuitive to have two equally perfect “things” in every respect, yet different. A perfect circle exists in only one form, there cannot be two different and perfect circles. Therefore it seems that there can be only one perfect form for anything that exists.
If God performs a miracle, and this miracle must affect change in the world, he has altered the state of the universe. The universe after miracle X is not in the same condition as before miracle X. As we have just established that no two different things can both be perfect, we can say that the universe was either perfect prior to miracle x or after miracle x, but not both. The universe is God’s creation and thus it must be perfect in every regard. So if it was perfect prior to his intervention, then it cannot remain perfect afterwards. If he modified it in a way to make the world closer to perfection, that implies that it was not perfect prior to his intervention. In either case, we have a universe that God creates which is imperfect. This creates an unsolvable contradiction between God and the existence of miracles. God cannot cause miracles since that would either implied God is correcting a mistake, which he cannot make, or he is making the universe less perfect, which is also something he cannot do. Since miracles cannot exist with God or without God, miracles can never exist.
A possible rebuttal would an attack on my definition of miracle. Hume suggests that a miracle is not something that involves supernatural acts. For instance, he does not believe the parting of the Red Sea is a miracle in and of itself. However that the epiphany you have when you realize you are with God is where the miracle really exists. My argument does not address this definition miracle and I purposely defined a miracle in such a way as to exclude Hume’s understanding of a miracle. While Hume addresses an important part of a miracle, most people do feel that miracles affect some kind of change in the world. So my argument remains that miracles in the sense of the layman cannot exist.

Sources:
http://plato.stanford.edu/entries/miracles/