Dawkins is an evolutionary biologist, but in reality his main focus is in advocating the philosophies of empiricism and naturalism, which is exactly what this book is about. He starts off talking about the question of “how do we know?” which really is the realm of experts in epistemology. On page 15 he states “the only good reason to believe that something exists is if there is real evidence that it does”. On page 18 he says “Ultimately, it always comes back to our senses, one way or another”. This is typical empiricism. What he fails to notice, is that he makes an absolutely emphatic statement of an abstract presupposition for which he can have no observational evidence, because it is an abstract presupposition. Thus empiricism merely a guess. He does not know that what he said is true.
He does admit on page 16 of scientific models, that they “increase our confidence that the model really does represent reality”. The truth is that the scientific method increases our confidence that something is true, but does not prove anything with absolute certainty. What Dawkins understands science to be isn’t science in the sense that science used to mean knowledge (from the Latin scientia). He is describing Empiricism and the Philosophical claim that knowledge only comes from the senses, and that reason alone is not valid.
Later, on page 21, he gets onto Naturalism or Materialism, the belief that there is no Supernatural, that everything is material. His argument is that mysticism stood in the way of scientific research, and therefore there cannot be a supernatural realm. No, all that means is that people should be open minded. To swing from a precommitment to mysticism to a precommitment to naturalism is irrational. This sweeping statement presumes that there aren’t other avenues for education, such as the use of reason alone. In fact Dawkins himself asserts on page 15 “We should always be open minded, but the only good reason to believe that something exists is if there is real evidence that it does”. Yet his precommitment to Naturalism contradicts this claim to being open minded.
Starting on page 244 he gets into Hume’s defense against the miraculous, which basically states that if it is easier to discredit a witness to a miracle, than it is for an atheist to believe in a miracle, then you discredit the witness. In other words, he is simply asserting that his precommitment to Naturalism and Empiricism do not allow him to believe in miracles, even though he has yet to establish the rationality of either of those philosophies.
It is also interesting watching how he attempts to justify creation from nothing on pages 164 and 165. “The predictions made on the basis of the big bang model keep turning out to be right, and so it has now been generally accepted by most scientists”. Yes it is true that it is popular, but popularity doesn’t imply truth, just like bad Presidents show that democracy doesn't always get it right. The fact is that there is valid scientific dissent of the big bang theory for a number of reasons, which is why Dawkins can only allege that “most scientists” are OK with it. There is also a philosophical problem with how one can argue the scientific creation of something from nothing, since science assumes preexisting material things which cause other material things to exist.
On page 165 “Some scientists will tell you that time itself began in the big bang, and we should no more ask what happened before the big bang than we should ask what is north of the North Pole.” Well, north is the direction to the North Pole, so yes that is an absurd question to ask once there. However, now he has stooped to appealing to just “some scientists”. Granted he does admit “You don’t understand that? Nor do I”. So are we to believe something that he himself doesn’t understand?
Dawkins writes well, and is obviously quite persuasive to some people, however, his use of reason is sloppy and he is clearly content with propositions that he cannot justify rationally. I don’t think anyone could to a better job of arguing the case of irrational philosophies like naturalism and empiricism.