It seems that I could reply to Dawkins as follows: even though the maxima of qualities can be different, e.g., finite (and if such, then either physically attainable or not) or infinite (and if such, then either potentially or actually infinite), still, these maxima can be identified. Thus, there is indeed a “pre-eminently peerless stinker,” for example, a finite volume of air containing nothing but the molecules that produce the smell. Furthermore, any actual smell partakes of that pre-eminence by imitating it only to a lesser degree in a straightforward way, such as a volume of air with just a few of the smell-causing molecules. But though it’s true that the maximum of truth or goodness or nobility is approached differently from the maximum of smelliness, the former have maxima nonetheless. And no matter which example we pick, the maximum is an archetype of everything less than that maximum and causes it, though we have to show how for every case in point.
Again, e.g., the temperature of wood can only be so high before the wood bursts into flame and later on ceases to be wood. Hence yellow fire is the maximum of the heat that can inhere in wood, and fire in wood is caused by exposing the wood to the temperature of fire.
Or, the maximum of interest can be defined as something which so holds your attention that you are not thinking or feeling anything else. Then a subject can be more or less interesting, depending on how much it occupies your thoughts. The ideal of interest, though abstract, causes less interesting things, as people try to produce works that absorb you more than works of other authors, so as to lure you to choose them.
Update. Three more examples: (3) the Internet paragon of the green color is #00FF00. Every greenish color participates in this pure greenness more or less, and the “FF” in the middle causes the green hue to influence every color. (4) Perfect justice is giving everyone his due. Deviations from this perfection qualify as justice more or less, but all receive their quality of justice by comparison with the ideal of justice. (5) The best form of government is local (city or county level) with public enforcement, mixed lawmaking, and private court industry. Any government is good to the extent that it approaches this ideal, and the ideal causes people to set up governments according to it.
Our super-stinker will not be God, however, because smelliness is not a metaphysical perfection. Unlike truth, say, a more intense smell is not inherently better than a less intense smell, again, self-evidently from “wisdom.”
Then there is no need to prove the actual infinity of God. That can be done later as we uncover His attributes. Whatever the actual properties of “something which is truest, something best, something noblest,” God, we must judge, is all those things.