A great deal of time these days in spent promoting or combatting Intelligent Design. The entire argument seems to me

a battleground quite peculiarly suited for those who desire to exercise themselves in mock combats, and in which no participant has ever yet succeeded in gaining even so much as an inch of territory, not at least in such manner as to secure him in its permanent possession.
--Kant, Critique of Pure Reason

The Argument from Design has never been good philosophy, and as such will never be good biology. Intelligent Design seeks to find a moment of special Creation, in which an intelligent power engineered life from non-living materials. How this creation is more probable than the gradual rise of self-replicating molecules from blind chance, and thence their complexification to higher forms of life, is quite beyond me; and how such probability may be demonstrated without begging the question seems to me impossible. But allow me to make one statement: whether Intelligent Design is a successful theory or not, it cannot provide the proof of God's existence that its promoters wish. Actually, allow me to make another: evolution's success as a theory doesn't provide proof that God does not exist, nor does it allow for a blithely materialistic philosophy. Anyone looking in this arena for such proofs is bound to be disappointed, which will stop very few people from doing so.

Philosophy was defined by Plato as the love of wisdom; the practice of philosophy was the acquisition of knowledge. Aristotle refined these definitions, splitting science into various branches (which branches are more clearly bounded today), and giving philosophy the task of expounding on first principles and causes. Whenever these definitions have been forgotten, bad thinking emerges. Philosophers who attempt to predict natural laws based on first principles (a charming example may be found in Kepler's attempt to force the planetary orbits into a relationship with the Platonic solids. He wished to have a punch-bowl made to demonstrate his theory. My flippancy is unfair to Kepler, who was a real empiricist and made incomparable advances in astronomy) are quite as absurd as scientists who attempt to draw metaphysical conclusions from the most recent theory about the origin of life.

Opponents of evolution tacitly accept much of materialist philosophy in debating the Argument from Design. It presumes, for example, that proof of God's existence must emerge from within the structure of biological science. Biological science is not opposed to the existence of God; it is indifferent. It is concerned solely with examining and explaining biological phenomena. If we accept that such an examination is the only means of gaining knowledge, or neglect to examine the causes which make such a study possible, naturally we will find that the existence of God is unnecessary.

Indeed, a successful proof of Intelligent Design would push the boundaries of the concept of a Creator (presuming always that it found such a Creator to be transcendent, rather than another limited agent, e.g. extra-terrestrial life with a love of farming) past those which philosophy has given us, and which are generally negative. If one accepts the philosophical arguments for the existence of God, God is unknowable (barring special revelation), and many of His attributes are simply negations: He is bodiless, He is not an accident, etc. While these negations can limit our mistakes, they do not allow us to make many positive statements about the attributes of God. They do not, for example, allow us to conclude that He is a Trinity.

Intelligent Design's success would establish God as an actor on a level with other actors in the physical universe. That is, this success would show that, rather than constantly existing as the fundamental Act-of-Being, God acts just as limited creatures do, in a way determined by various accidents. Such a discovery would not indicate miraculous doings, which are simply the expression of higher laws than are commonly understood. It would be an entering of God into creation as a limited being. Philosophically, this is nonsense; theologically, there has been precisely one such episode: the Incarnation.

St. Thomas Aquinas has something rather like the Argument from Design as his Proof from the Final Cause, but with such changes as demonstrate that he was all too aware of the difficulties of the common form of this argument.

It is impossible that contrary and disparate things should be in accord and reconciled within the same order, either always or very often, unless there exists a being governing them and causing them, collectively and individually, to tend towards one determined end. Now we observe that in the world things of different natures are reconciled within one and the same order, not merely from time to time and by chance, but always or practically always. There must then exist a being by whose providence the world is governed, and it is this being that we call God.
--Contra Gentiles

Note the important difference. God does not arrange the world as though He were playing Tetris. By governing it and causing it, He creates order. Evolution, to St. Thomas, would be a dramatic confirmation of his proof: disparate elements acting in accord. God, here, is not the object of an hypothesis; He is the reason that hypotheses may be made. The Argument from Design degrades the dignity of God by artificially limiting His methods of creation, and degrades the dignity of truly philosophical arguments when it is placed alongside them.