You are capable of doing less good than you have the capacity to do. You sometimes lie when you could have told the truth, you are less charitable, compassionate, loving, and forgiving than you are capable of.
You are also able to exert less power than you are fully capable of. You lift a single grocery bag when you could have carried three. You run slower than your limit. You don’t perform actions that are within your capacity. In some cases, there are external forces, events, or obstacles that thwart the exertion of your power. And in some cases, the restriction on your exertion of your power is your choice; you have failures of knowledge, character, virtue, or wisdom.
You also have less knowledge than you are capable of having. There are logical theorems that you could prove on the basis of things you already believe, but you haven’t put the intermediate steps together and made it explicit knowledge. There are things you just don’t know because of your limits; you don’t know the cure for cancer or how to build a spaceship for interstellar travel. And no amount of effort would produce that knowledge for you.
God, I submit, would not act in any sub-maximal ways with regard to knowledge, power, and goodness. God, by the conventions of traditional theism, possesses all knowledge. God knows all and only truths. There is no fact that is knowable not known by God. Furthermore, God is the almighty, all-powerful creator of the universe. But not only did he create the totality of this universe, his power includes the capacity to do all things that are doable. He could have made any number of other universes, including those requiring more power. He can do any action that is logically possible. And finally, God is an infinitely good, morally perfect being. God has endless love, limitless virtue, and is a being that cannot be morally exceeded in any way. God is omnibenevolent.
God would not act in ways that are inconsistent with infinite power, knowledge, and goodness. You can and often do act in ways that are sub-maximal, given your knowledge, power, and goodness. Sometimes through some fault, imperfection, or error, you choose the wrong action; if you had more knowledge, or if you even had more of the knowledge that you are capable of possessing, you would have chosen better. But God will never act in some sub-maximal way because of this sort of failing. God lacks no knowledge. Sometimes, you exert less power than you are capable of because of laziness, a lack of goodness, a character fault, or a lack of knowledge. God won’t act sub-maximally in any of those regards because of his infinite knowledge and moral perfection. Sometimes, even exerting all of your power you fail to achieve your ends, you are thwarted, or you fail because there are other external forces that exceed your power; you are overpowered. God, being infinitely powerful, cannot be overpowered by external forces. Sometimes you do less goodness with your actions than you are capable of or than you should have done. You lack goodness, virtue, or character. Maybe you could have done better, but you didn’t. Or maybe the act in question is simply beyond the limits even of your acting to your full potential goodness. God, being infinitely good, morally perfect, infinitely loving, won’t act sub-maximally in any of these ways.
Miracles are violations of the laws of nature. To walk on water, raise the dead, or feed thousands with a few fishes and loaves of bread would all violate physical laws such as the conservation of matter, the conservation of energy, the density of matter, entropy, and so on.
Miracles are also limited with regard to knowledge, power, and goodness. That is, an agent performing a miracle need only have enough power to perform that miracle, to raise that corpse from the dead, or sustain that instance of walking on water. Miracles only require sub-maximal power, knowledge, and goodness. We might think that infinite power, knowledge, and goodness are sufficient for performing miracles too. But, as we have seen, infinite power would express itself perfectly and fully, reflective of all knowledge and goodness, in God’s case. To cure a leper is to leave thousands or millions more uncured. To raise one corpse from the dead is to leave millions or billions of others in the grave. To feed one hungry crowd is to leave millions or billions of others starving. An action of such limited scope is consistent with the actions of a being that has limited knowledge, power, and goodness. But it would be inconsistent, contrary to the expressions of a being with infinite properties.
It’s not merely that by doing a miracle God would be acting at levels that are within but below his limits; such a limited action is precluded by God’s infinite nature. Limited actions are as much outside the capacities of God as performing miracles are outside of yours. Can or would God sin? No. Can or would God be less than perfectly moral? No. Can or would God exert less power in the world than he is capable of? No. Can or would God act in ways that defy or neglect his infinite knowledge? No. Miracles, however, achieve limited goals. Miracles would not be within the tool set, or expressed actions of a being that has no limits or imperfections. However, miracles insofar as they imply limited power, knowledge, and goodness are quite plausible as the actions of finite, imperfect beings who lack power. That is suggestive about why they strike us as so important and interesting, but miracles simply do not make sense as expressions of the goals or actions of a being so vastly beyond us in power, knowledge, and goodness.
I have argued:
1. God wouldn’t act in any ways that are below capacity.
2. Performing a miracle would be acting below capacity for God.
3. Therefore, God wouldn’t perform miracles.