Those who oppose scientism usually operate under the misapprehension that science is some kind of intellectual subculture or institution, which some hope to promote above other subcultures and institutions. Rosenberg cuts through this pernicious nonsense by pointing out that the word ‘science’, used properly, only refers to common sense rigorously applied. It is ‘just common sense continually improving itself, rebuilding itself, correcting itself, until it is no longer recognizable as common sense’ (167). For example, at first common sense told us that bodies in motion naturally slow down over time. Galileo refuted this intuitive conclusion by using better common sense, in the form of his thought experiment about incline planes. To be scientific is just to apply common sense relentlessly and inventively until reasonable doubts have been eliminated, and making new discoveries along the way. It is hard to see that any method based entirely on common sense can get you to quantum physics. But it does.

Science – i.e. common sense – tells us that atheism is pretty much a certainty. The reason is quite straightforward. The second law of thermodynamics tells us that disorder and homogeneity steadily increase everywhere in the universe. Whatever physics has left to tell us, it almost certainly won’t contradict this fundamental law. But a purposeful agent, arranging things according to a conscious plan, would be transforming disorder to order. And this is never possible according to the second law (strictly speaking, it is possible, but so improbable as to be ruled out). This rules out most conceptions of God straight away.

Science can also explain why so many things appear to have been consciously designed. They appear this way because they have been produced by a process of natural selection: blind variation, combined with environmental filtration. The latter refers to the process by which types of things that lose out in a competition for survival are eliminated. This latter point is crucial and not dwelt upon enough by most popularisers of the theory of natural selection. What it explains, as Rosenberg makes vivid, is why natural selection doesn’t constitute a violation of the second law. It makes things appear to progress from disorder to order, since the surviving types are increasingly complex and well-adapted. But it achieves this by creating a huge amount of waste. Everyone remembers how nature, according to Darwin’s theory, produces an incredible diversity of orderly creatures. Most people forget that its primary product is a mountain of formless rubbish – all that remains of the types that didn’t make it (‘From scarped cliff and quarried stone…’) Even today’s species will eventually end up in the dustbin of natural history. Natural selection’s primary product, like that of any natural process, is disorder, not order. That’s why the theory of natural selection, unlike any theory of conscious design, is compatible with the second law. In fact it is an application of it.

The scientific argument for atheism is, then, much stronger than even Richard Dawkins seems to have realised. But what keeps most people besides Rosenberg from stressing this point is perhaps that the conclusion of the above argument seems much too strong. It doesn’t just rule out God; it rules out conscious design in general. This contradicts an intuition people hold to much more strongly than to any religious faith. Divine purpose there may not be, but surely we are capable of bringing about order through conscious design. If Rosenberg is right about the second law, shouldn’t it rule us out?

This is where the book gets onto a topic far more interesting than the atheism celebrated in its title. Vividly and painstakingly, Rosenberg undermines our fundamental belief that we consciously direct our actions. He argues that it is impossible that any of the processes occurring in our brain can have representative content. They can’t be about anything at all. The failure of contemporary philosophers of mind to come up with a remotely plausible naturalistic theory of representation counts very strongly in favour of his argument. But science compels us to believe that brain processes are the only causes of our voluntary actions. They are the only identifiable physical causes of our actions, and the supposition that our actions have non-physical causes is scientifically indefensible. This means that our actions can’t, however much they seem to, be caused by thoughts about intended results, or indeed thoughts about anything at all. Nothing is more natural than believing that part of what caused me to buy bread today was a thought about the absence of bread in my house and my intention to have toast in the morning. But this can’t be right; what caused my action was a group of brain processes that were not about bread, nor about tomorrow morning, nor about my house, nor about anything at all.

Despite appearances, then, we aren’t capable of ordering the world by conscious design. In fact, our actions are never caused by conscious intentions. This is a lot to swallow, but, again, it is worth stressing that Rosenberg is simply embracing a conclusion that naturalistic philosophers have struggled unsuccessfully to avoid for a long time.

Of course explaining human actions in terms of conscious intentions is not something we’re going to give up doing. Practically speaking, it is indispensible. Try driving your car or having an ordinary conversation without predicting and interpreting people’s actions in terms of their likely intentions. According to Rosenberg, natural selection implanted us with the illusory notion of intentional agency because it was the simplest way of making us capable of coordinating actions with our conspecifics. At the same time, although this illusion is practically indispensible, its practical applications are seriously limited. We can’t use it to predict people’s actions with any respectable degree of precision; if we could, everyday life would be easier and more boring. Our intention-driven explanations of human action are, Rosenberg claims, ‘not even approximations. They are at best rough indicators’ (245).

Once Rosenberg has this claim in place he can go on to debunk history, biography, literature, and the social sciences. All of these explain human actions as if they are caused by conscious intentions. Their explanations are, therefore, no more accurate than the ‘rough indicators’ of ordinary folk psychology.

It is worth dwelling on what this entails. Human life as a whole has no meaning, no goal, and no purpose. Neither our individual lives nor human history in general are governed by purposes – not our own, and not anybody else’s. Absolutely everything is governed by the second law and by the careless and blind process of variation and filtration. Your inspiring story of recovery from alcoholism becomes meaningless. All that happened is that the control mechanisms in your brain hit on some chance adaptation that gave them the upper hand over the addiction mechanisms. It might last, but it might not – the addiction mechanisms might hit on some chance adaptation of their own. You have no say over any of this. Indeed, there is no ‘you’; the self is another one of those convenient fictions we use to roughly indicate blind processes that have no subjective centre.

The same goes for human history. All apparent progress – the spread of democracy or the global progression towards prosperity – are just local equilibria in a blind arms-race driven by blind selection. Sooner or later the forces countervailing against these trends will chance upon some adaptation that will tip the balance right over to the other side. Again, the crucial point is that we have no say. Life is a walking shadow. History is one damn thing after another. This is not a worldview or a belief system; it is a mere reading off of the scientific facts as they apply to human life and history. Freedom from illusions of progress and purpose should, Rosenberg says, allow us to enjoy life. Hence the subtitle of the book. Strut and fret your hour upon the stage, then out brief candle. No worries.

This is the part of the book I’m surprised fewer people have commented on. These claims about the consequences of taking science seriously are, one might say, rather bold. Rosenberg’s arguments also make them far too compelling for comfort. When Rosenberg put forward some of his views in The New York Times, he received responses from William Eggington, who didn’t understand the argument, and from Tim Williamson, who didn’t really address it. But Rosenberg hasn’t made his full case until now. His ideas about representation and intentionality have been developed throughout his career. But it is only in The Atheist’s Guide that he puts forward the bold view that science proves both folk psychology and the humanities wrong, not on some point of detail, but on the fundamental idea that human lives can be guided by purposes of some kind or other. Here I would have thought plenty of people would have liked to take issue.  But they have remained quiet.

Again, this might be down to a mistake in marketing. The Atheist’s Guide is perhaps too popular in its tone for serious philosophers to respond to, while its most interesting arguments are far too complex for non-philosophers to engage with in a productive way, as the exchanges with Eggington amply demonstrate.

There are other parts of Rosenberg’s book that might attract some attention – his defence of ‘nice nihilism’ in metaethics, for example. There are also some interesting points concerning how scientism might affect one’s attitude towards abortion and income redistribution, addressed largely to an American audience. But I think the attack on folk psychology and the notion of purpose is by far the most interesting part of the book. And I think there is room for serious debate, even if Rosenberg turns out to be right about the impossibility of consciously purposive agency (as I, probably more than most philosophers, suspect he is).

After all, even if conscious purposes are never the causes of our actions, explanations that deal in conscious purposes might be useful to varying degrees. They may be only rough indicators of the real causes of our actions. But how rough is rough? A model that deals in fictional causes might still be quite reliable as a system of prediction, and, at some level, of explanation. Here Rosenberg asserts that the unreliability of folk psychology is plain for all to see. But this rides over a number of important distinctions. For example, some people seem to be better at propounding such explanations than others. Flaubert and Dr. Johnson explained human actions in terms of conscious intentions, and so do politicians and evangelists in the tawdry claptrap they spout. Folk psychology seems to accommodate levels of insightfulness from the ingenious down to the idiotic.

Moreover, there are more and less interesting facts to be roughly indicated. Philip Larkin roughly indicates something when he writes that ‘death is no different whined at than withstood.’ Pastor Rick Warren roughly indicates something else when he writes that ‘the most damaging aspect of contemporary living is short-term thinking.’ But there is a difference in the freshness and the profundity of the facts indicated.

Of course Rosenberg’s point is that all rough indication, the brilliant and the dull, the profound and the inane, will be outmoded when neuroscience progresses to the point of being able to explain and predict human actions without any recourse to the useful fiction of conscious purpose. But this day is far off, if it will ever come. For the moment we’re stuck with the rough indicators, and we might as well learn who uses them well and, if possible, how they do it. This seems to comprise a great deal of what the humanities are about.

Rosenberg sometimes speaks as if works of history and fiction can hope to do no better than being fun or stirring (social science does a little better, but not much). But this doesn’t follow from the premise that such works ascribe unreal causes to human actions. What Proust revealed about human life he revealed by writing about characters who were mostly fictional, involved in events that for the most part did not occur. Should we give up on believing in his insightfulness just because we learn that the causal mechanisms he invoked are fictional as well? And Faulkner was perhaps right to remind us that even if life is a tale told by an idiot, there remains some interest beyond mere entertainment in commenting upon the sound and the fury.

At any rate, The Atheist’s Guide is a book that deserves more attention than I believe it has gotten. I am fairly certain this post won’t do anything to help. But at least now I can feel like I’ve tried. Not, of course, that I did, if Rosenberg is right.