I'll have to read through this again. Something makes me uncomfortable with the logic of the author. And this also applies to many that try to should down the philosophical arguments for the existence of God.
The historical arguments of interest are precisely the potentially problematic ones—inferences beginning with some empirical features of nature taken as (or argued to be) design-indicative, and concluding with the designedness of, and a designer of, the phenomena in question. A standard but separable second step—the natural theology step—involves identifying the designer as God, often via particular properties and powers required by the designing in question. Although the argument wielded its greatest intellectual influence during the 18th and early 19th centuries, it goes back at least to the Greeks and in extremely clipped form comprises one of Aquinas's Five Ways. It was given a fuller and quite nice early statement by Hume's interlocutor Cleanthes:
Look round the world; contemplate the whole and every part of it: You will find it to be nothing but one great machine, subdivided into an infinite number of lesser machines, which again admit of subdivisions to a degree beyond what human senses and faculties can trace and explain. All these various machines, and even their most minute parts, are adjusted to each other with an accuracy which ravishes into admiration all men who have ever contemplated them. The curious adapting of means to ends, throughout all nature, resembles exactly, though it much exceeds, the productions of human contrivance; of human design, thought, wisdom, and intelligence. Since, therefore, the effects resemble each other, we are led to infer, by all the rules of analogy, that the causes also resemble; and that the Author of Nature is somewhat similar to the mind of man, though possessed of much larger faculties, proportioned to the grandeur of the work which he has executed. By this argument a posteriori, and by this argument alone, do we prove at once the existence of a Deity, and his similarity to human mind and intelligence. (Hume 1779 , 15).
That statement captures much of popular, informal design intuitions, but exactly how ought we to construe the formal structure of such arguments? What sort of logic is being employed? As it turns out, that question does not have just a single answer. Several distinct answers are canvassed in the following sections.
I also feel that he's a bit biased concerning intelligent design, but still I'd say he's trying to give a fair account. At least he admits that the anti-ID pro-evolution proponents are emotional to fallacious in their arguments as well.
4.3 The “Intelligent Design” (ID) Movement
A high-profile development in design arguments over the past decade or so involves what has come to be known as the “Intelligent Design” (ID) movement. Although there are variants and unclarities, the movement involves efforts to construct design arguments taking cognizance of various contemporary scientific developments (primarily in biology, biochemistry, mathematics and cosmology)—developments which, as most ID advocates see it, both reveal the inadequacy of mainstream (naturalistic Darwinian) explanatory accounts (condition (a)) and offer compelling evidence for design in nature at some level (condition (e) again). ID advocates have tried to establish not only the rational cogency of design cases but have pushed ID as legitimately scientific by trying both to define relevant Rs with adequate empirical precision and to construct design arguments with suitable scientific/mathematical rigor.
ID advocates propose three specialized Rs—irreducible complexity, specified complexity and information. Although distinctions are sometimes blurred here, while ID arguments involving each of those Rs tend to be gap arguments, an additional focus on mind-reflective aspects of nature is typically more visible in ID arguments citing specified complexity and information than in arguments citing irreducible complexity. Gaps are also a defining feature of the “explanatory filter” frequently endorsed by ID advocates.
The movement has elicited vociferous criticism and opposition. Opponents have pressed a number of objections against ID including, inter alia contentions that ID advocates have simply gotten the relevant science wrong, that even where the science is right the empirical evidences cited by design advocates do not, in fact, constitute substantive grounds for design conclusions, that the existence of demonstrably superior alternative explanations for the phenomena cited (Darwinian, many-universes, etc.) undercuts the cogency of ID cases, and that design theories are not legitimate science, but are just disguised creationism, God-of-the-gaps arguments, religiously motivated, etc.
I will not pursue that dispute here except to note that even if the case is made that ID arguments could not count as proper science (and arguments for that more general claim are controversial), that would not in itself demonstrate some deeper rational or inferential defect in design arguments as such. Science need not be seen as exhausting the space of legitimate conclusions from empirical data.
But the floods of vitriol in the current ID discussion suggest that much more than the propriety of selected inferences from particular empirical evidences is at issue. Although there is indeed much more that energizes the squabble on both sides (political, cultural, philosophical and, in some instances, religious) there is one further aspect of the ID attempt which ties in here, but which is also relevant to one final larger question.
Anyway, I'd like to look through the whole argument from design concerning the existence of God. Note that this is about philosophical proofs for the existence of God. This is separate from divine revelations, while one could actually also construe the general prevalence as evidence, too.