As my acquaintances may guess, I am broadly sympathetic to these sorts of ideas. I'll come right out and say that I think the world would be a better place, on balance, without religion, and I too resent the privileged status granted to religious beliefs such that they are considered to be above criticism. Believing something to be true in the absence of supporting evidence is, to put it mildly, silly, and when the evidence is in opposition to your belief, well, then, you're just being willfully stupid.
When it comes to matters of faith, though, a great many people are willfully stupid, and a great many of the criticisms of The God Delusion are predictably unintelligent. There is the fair charge that the book is poorly edited and contemptuous, but none of that speaks to the merits of its argumentation. I'd like to have read a clearer, more disciplined book, but that sort of quibble is a distraction. It's also true that Dawkins could have been more polite in his delivery but, again, the most this gets you as a criticism is that the book is likely to offend people it could otherwise persuade.
To date, I've read only one insightful criticism of this book, and it comes from Thomas Nagel. I'd known that Nagel had written a review , but prior to reading the book I didn't see why I should particularly care what he had to say about it since it wasn't obviously his field. Dawkins, though, makes some dismissive comments about moral absolutism and ontological dualism. After reading the book, I can see why Nagel would be interested, since Nagel is among the world's foremost advocates of both moral absolutism and ontological dualism. And besides, Nagel's a genuinely brilliant guy - a fact I can testify to not just as a result of reading his work but also from personal experience - so, I signed up for a trial subscription to the otherwise-lame New Republic just to read what he had to say.
Nagel's objection boils down to this:
The fear of religion leads too many scientifically minded atheists to cling to a defensive, world-flattening reductionism. Dawkins, like many of his contemporaries, is hobbled by the assumption that the only alternative to religion is to insist that the ultimate explanation of everything must lie in particle physics, string theory, or whatever purely extensional laws govern the elements of which the material world is composed.In other words, Dawkins has succumbed to the temptation to think that everything that exists has to be explained exclusively and ultimately in physical terms. Initially, Nagel dismissively refers to this as "amateur philosophy". Eventually he concedes in an off-hand way that there are actually a lot of questions left unanswered by "[a]ny anti-reductionist view", but the gist of the complaint seems to be that if Dawkins had just read "What is it Like to be a Bat?", his book would be very different (and, presumably, better.)
This reductionist dream is nourished by the extraordinary success of the physical sciences in our time, not least in their recent application to the understanding of life through molecular biology. It is natural to try to take any successful intellectual method as far as it will go. Yet the impulse to find an explanation of everything in physics has over the last fifty years gotten out of control. The concepts of physical science provide a very special, and partial, description of the world that experience reveals to us. It is the world with all subjective consciousness, sensory appearances, thought, value, purpose, and will left out. What remains is the mathematically describable order of things and events in space and time.
Now, I think Nagel is right that Dawkins is too dismissive of dualism in general, probably because his exposure to philosophy is limited. You can file a similar complaint against Dawkins's contempt of moral absolutism, best captured by this bit from pg. 232:
Moral philosophers are the professionals when it comes to thinking about right and wrong. As Robert Hinde succinctly put it, they agree that 'moral precepts, while not necessarily constructed by reason, should be defensible by reason'. They classify themselves in many ways, but in modern terminology the major divide is between 'deontologists' (such as Kant) and 'consequentialists' (including 'utilitarians' such as Jeremy Bentham, 1748-1832). Deontology is a fancy name for the belief that morality consists in the obeying of rules. It is literally the science of duty, from the Greek for 'that which is binding'. Deontology is not quite the same thing as moral absolutism, but for most purposes in a book about religion there is no need to dwell on the distinction. Absolutists believe there are absolutes of right and wrong, imperatives whose rightness makes no reference to their consequences. Consequentialists more pragmatically hold that the morality of an action should be judged by its consequences.Since Dawkins himself had pointed out only a few pages earlier that there are very plausible arguments that Kant was himself an atheist, it's not clear why he now dismisses deontologists out of hand as religious nuts. Certainly today there are no shortage of non-religious deontologists among the ranks of those moral philosophers who "are the professionals when it comes to thinking about right and wrong." (Nagel is one, as a matter of fact.)
Not all absolutism is derived from religion. Nevertheless, it is pretty hard to defend absolutist morals on grounds other than religious ones.
One is forced to conclude that Dawkins isn't actually very familiar with the ins-and-outs of contemporary philosophy, since he seems oblivious to the widely-respected arguments for both ontological dualism and ethical absolutism. In both cases he just assumes - without any evident reason - that the position he disfavors is necessarily bound up with religion, and must therefore be summarily tossed out.
Plainly put, Dawkins is wrong to reject dualism and absolutism on the basis of the arguments he offers. At the same time, those technical philosophical criticisms have almost no practical impact on the arguments of the book. One need not reject ontological dualism to point out that religious people ascribe all sorts of ridiculous characteristics to the non-physical world and tend to assume that if non-physical phenomena exist, they must be the sort of phenomena that are described in, for instance, the Bible. Similarly, one need not reject moral absolutism to acknowledge that religious groups tend to come up with really lousy moral absolutes.
In other words, Dawkins assumes in multiple instances that when the content of religious beliefs is absurd, the underlying ethics or metaphysics must be equally absurd. That's a baby-with-the-bathwater mistake, and Dawkins of all people probably has friends who could have helped him clarify his thinking. Instead, he gets the philosophy wrong even though it's got no significance to his central thesis: namely, that we'd do well to get rid of religion altogether.
Update: Because Tom asked, and because I felt like this post wasn't quite long enough, I thought I'd expand on my thoughts on dualism a little bit.
I personally don't know that I subscribe to dualism. But I don't think I'm really committed to monism, either. My issue with Dawkins is that he just acts like dualism is obviously wrong, but in fact that is one of the central and most contentious questions in contemporary metaphysics.
I think dualism's got problems - most notably, a dualist has got to give some account of how it is that an essentially non-physical thing can interact causally with a physical thing (without running into conservation of energy problems, no less!) But dualism also has some very powerful arguments going for it.
The gist of the problem was formulated with force by Nagel, in that "Bat" article I linked to.
I have said that the essence of the belief that bats have experience is that there is something that it is like to be a bat. Now we know that most bats (the microchiroptera, to be precise) perceive the external world primarily by sonar, or echolocation, detecting the reflections, from objects within range, of their own rapid, subtly modulated, high-frequency shrieks. Their brains are designed to correlate the outgoing impulses with the subsequent echoes, and the information thus acquired enables bats to make precise discriminations of distance, size, shape, motion, and texture comparable to those we make by vision. But bat sonar, though clearly a form of perception, is not similar in its operation to any sense that we possess, and there is no reason to suppose that it is subjectively like anything we can experience or imagine. This appears to create difficulties for the notion of what it is like to be a bat. We must consider whether any method will permit us to extrapolate to the inner life of the bat from our own case, and if not, what alternative methods there may be for understanding the notion.
Our own experience provides the basic material for our imagination, whose range is therefore limited. It will not help to try to imagine that one has webbing on one's arms, which enables one to fly around at dusk and dawn catching insects in one's mouth; that one has very poor vision, and perceives the surrounding world by a system of reflected high-frequency sound signals; and that one spends the day hanging upside down by one's feet in an attic. In so far as I can imagine this (which is not very far), it tells me only what it would be like for me to behave as a bat behaves. But that is not the question. I want to know what it is like for a bat to be a bat. Yet if I try to imagine this, I am restricted to the resources of my own mind, and those resources are inadequate to the task. I cannot perform it either by imagining additions to my present experience, or by imagining segments gradually subtracted from it, or by imagining some combination of additions, subtractions, and modifications.
It is difficult to understand what could be meant by the objective character of an experience, apart from the particular point of view from which its subject apprehends it. After all, what would be left of what it was like to be a bat if one removed the viewpoint of the bat?
Reducing the mind down to physical facts about the body isn't like, say, reducing proteins down to individual amino acids, he thinks, because mental phenomena are necessarily subjective, while the physicalist project is aimed at moving toward ever-increasing objectivity. I can imagine, at best, what it would be like for me to be a bat, but no amount of physical knowledge could possibly let me know what it's like for the bat. This isn't a problem about being able to reproduce neurological states; it's a problem about being able to actually occupy a point of view that's not your own.
I think Nagel identifies a very real problem here, but Frank Jackson probably did it more clearly in "What Mary Didn't Know", the central argument of which is this:
Mary is a girl who is locked up in a black and white room without windows, where she is taught every physical fact about the world (using, of course, only black and white materials.) If it is actually possible to explain everything in the world in terms of physical facts, Mary knows everything there is to know.
Presumably, though, if Mary is then let out of the room, she will learn something new: namely, what it is like to see, for instance, red.
The underlying concern in both cases is that mental phenomena seem to have these subjective properties - "qualia", in the jargon - that you just can't get at with any quantity of physical knowledge. It's difficult to see how any set of physical facts could possibly lead to knowledge about what a mental phenomenon is like.
Of course, the way that philosophy works is that a lot of very smart people - Dawkins's buddy Daniel Dennett, for instance - have come up with really brilliant reasons why we shouldn't think that Mary learns anything new at all when she leaves her room. But it's not like the case has been closed, and my only real problem was with Dawkins acting like it was.
For my own part, I have physicalist sympathies, and I get the impression that monism generally is on the rise these days. But I am by no means confident that I could ever know what being a bat is like for a bat, and I think that's a real dilemma.