Chapter 4, the longest chapter in The God Delusion (about 53 pages), is titled "Why there almost certainly is no God" (137-189). It is safe to say that this is where Dawkins sees his strength, but I found this chapter to be among the weakest in terms of argumentation. Here are some examples:
1. Dawkins says that "Darwinian natural selection is the only known solution to the otherwise unanswerable riddle of where the information comes from" (138). But this is certainly too broad a statement. Even if Darwinian natural selection is as explanatory as Dawkins thinks it is, it still doesn't explain where information ultimately comes from.
2. He hints that even though there's no evidence, a darwinian principle may actually have application to origins/cosmology (139, 141, 143). To me, this is direct evidence that Dawkins is working more from a worldview than from actual observation (as he claims).
3. He makes a repeated (and good) point that Darwinian evolution really isn't a 'chance' ordeal (145). I think it is too easy for non-Darwinians to dismiss the theory as one of (statistically impossible) chance. The kind of evolution that we all agree about is not a matter of 'chance' at all. It happens for a reason.
4. Dawkins insists that the design argument is flawed in that the designer's origin, too, would need to be explained (being a complex being and all, 146-147). But again, the argument only states that things that have a beginning (like the cosmos) have a cause. "Who made God" simply isn't a legitimate question b/c God is, by definition, a being without a cause.
5. Dawkins writes as if creationists don't understand the principle of accumulation. I respond by saying that I probably believe in it even more than Dawkins does. After all, I believe that the variety that we see came about in a (relatively) short period of time via evolution.
6. In my opinion, Dawkins has an epistemology that makes his conversion (to theism or something like it) practically impossible. He states that it doesn't even make sense to search for evidence of design (151, 153). Instead, one should always assume that anything with the appearance of design is just an area of current human ignorance. How can irreducible complexity EVERY be shown if it is ALWAYS better to wait for more science (155)?
7. In this same context, he states, "It is utterly illogical to demand complete documentation of every step of the narrative" (153). But his discussion of God in the Old Testament is evidence that he does not extend that sort of grace to theists.
8. From the opening quote of Jefferson to the end of the chapter, Dawkins is attempting to ignite the supposed flaming gulf that exists b/w religion and science. But no such gulf exists. Good theism doesn't wish science would go away, nor do good theists shy from it.
I'll stop at 8 (it's a long chapter). Next I'll look at what Dawkins says about the Anthropic Principle (and probably be able to finish the chapter).