The Spirit Level is a book that has had as great an impact as any on recent political discourse. Its thesis, that inequality in society is bad for everyone, is backed up by a storm of statistics. And in turn has provoked a storm of rebuttals, which say the evidence presented proves no such thing.

All credit to the RSA for bringing together the book's two authors and two of its biggest critics. So who won the hour long debate? It was a stalemate, if the audience is anything to go by: at the end, Matthew Taylor asks whether anyone's mind has been changed, and one person alone admits as much.

I'm not surprised, as the authors and the opponents present exactly the same defence/critique to make their opposing cases. Regression analysis, removal of outliers, the small samples - standard statistical methods. To one side, that's the strength of the case. To the other, its weakness.

So what to make of it? Well, I sided with the critics, not really because of their evidence, but because they seemed to me to make the important, bigger point. You just can't derive policy from evidence when it comes to systems as complex as human societies. Instead, you must make the ethical case for what you want to do. That's hard. But that's, presumably, only because politics is hard, and any shortcuts are a delusion.

Darian Leader was very fascinating about mourning, yesterday at the Edinburgh book festival. He noted that mourning changed from having a big public dimension to being personal and private with the First World War: there were simply too many deaths for the Victorian rituals of mourning to cope with. But, he mused, has this made mourning more difficult for us or just different?

That it might have become more difficult is supported by considering the nature of mourning. It seems to require a public dimension, as the sadness of death is not just an inner trouble, but is about re-establishing your relationship with the world. As Lacan observed, when someone dies, you don’t just lose them, but you lose yourself as you were with them. Finding yourself again, then, is a social act – which perhaps explains why many cultures have professional mourners, though not our own, unless you count undertakers dressed in black. It’s their very artificiality, or symbolic role – like dressing in black – which announces that something foundational is taking place, and that all are involved.

Similarly, there’s the ancient thought that ‘nature mourns with you’: the mourner’s world has to be remade and that requires a remaking of the world too. Or, in Hamlet, the Danish prince can only mourn when he sees Laertes ostentatiously mourning: then, Hamlet's loss is externalised, and only in ceasing to be a self-obsessed inner concern can the mourning really begin.

Leader reflected that the shopping streets of Victorian Edinburgh would not have known the brands of today, though they would have had ‘mourning shops’, places to buy the paraphernalia of mourning - clothes and the like. It seems morbid to us. But perhaps there was a lost wisdom in it.

Why is Sherlock Holmes such an engaging character, proven so again in the BBC mini-series? He is as a sun to poor Dr bag-carrying Watson's moon (whom they tried to make interesting though his character spun off in all directions), or even Moriarty (who was played as hideous camp, which is surely too easy.)

After all, he's a self-absorbed narcissist, addicted to distractions, so evidence obsessed as to be blind to human values - in short, a 'high-functioning sociopath', as he describes himself. But isn't that it? Is it too harsh to think he's modern man distilled? Hence we find him fascinating.

Week after week after week. The Secret is persistently amongst the top ten non-fiction (I use the word advisedly) bestsellers. Why? What's with this small tome of esoteric self-help advice? I stole a look in a bookshop. And William James provided the key to unlock the secret of The Secret.

It's an example of what he called a 'mind cure', and he'd noticed a variety of mind cure movements growing in the quarter century before he gave his lectures on The Varieties of Religious Experience - which is to say that they emerged in the nineteenth century. The essential doctrine that links an otherwise diverse philosophy is that thoughts are things. So to change your thoughts is to change things as they are in the world.

That is linked to a dominant optimism - and it attracts individuals with an optimistic temperament, particularly those to whom doctrines like Christianity's original sin, or psychoanalysis's dark unconscious, seem ugly and pessimistic. That, it turns out, is a lot of people, hence the success of the various forms of mind cure - which range from the power of positive thinking, through Christian Science, to more scientifically informed versions like CBT.

The Secret appears to be just a simplified form of this mental hygiene: if your thoughts are of health or insight or wealth then before you know it, you will receive health or insight or wealth. (Similarly, to think you are ill or ill-fated is simply not to be thinking right: you are well, and will know it.) It's believed this happens because of a universal law that like attracts like. And, if you align yourself to the benign flux of life, then things can only go well.

Vasari said of it: 'The whole world came running when the vault was revealed, and the sight of it was enough to reduce them to stunned silence.' Michelangelo's ceiling of the Sistine Chapel. Thanks to Guy for sending this stunning online tool for viewing every detail, without the crowds.

Just been writing a piece on Philip Pullman's new novel, The Good Man Jesus and the Scoundrel Christ (watch this space). Brilliantly done, as you'd expect.

The new book came after a conversation Pullman had with Rowan Williams, and having a copy of that, I read what they'd said again. It's fascinating, but I wanted to record what Pullman said about education.

'...whether you think that the true end and purpose of education is to help children to grow up, compete and face the economic challenges of the global environment we're going to face in the 21st century, or whether you think it's to do with helping them see that they are the true heirs and inheritors of the riches - the philosophical, the artistic, the scientific, the literary riches - of the whole world. Do you believe in setting children's minds alive and ablaze with excitement and passion or is it a matter of filling them with facts and testing them on them? It depends on your vision of education - and I know which one I'd go for.'

A little blasphemy: I didn't like A Single Man, Tom Ford's rendition of Christopher Isherwood's novel. Colin Firth is brilliant: he portrays George's quiet agony very movingly. It seemed that some of Isherwood's best lines are kept in. But the filming was all too self-consciously artful for me.

The colour saturation went up every time a beautiful boy appeared on screen, who of course had rose bud lips. The camera lingered on Firth mostly to enjoy the cut of his clothes. The attention to sixties styling meant we didn't see an era but a catalogue. The policing of taste; aesthetics smothering reality; the claustrophobia because no object is allowed simply to be. Isherwood wrote, 'I am a camera with its shutter open, quite passive, recording, not thinking.' If only.

Julian Baggini has managed to elicit a fairly clear statement of Jerry Fodor's objections to the theory of evolution in The Philosophers' Magazine:

The idea that there may in fact be no general account of how evolution works is one of the more intriguing of Fodor's suggestions. The idea is that natural history may be just like ordinary history, and that Darwin's attempt to provide an overarching theory of natural history is as misguided as Marx's attempt to have a one-size-fits-all theory of human history.

'It's a very typical nineteenth century phenomenon, to try to get theories of history,' says Fodor. But real history is fine-grained, with much scattering of detail. 'One possibility is that all these fine-grained historical sequences that we know about, sequences of cause and effect, have something in common; the other is that no general theory can deal with this, that the stories you can tell are indeed these very fine-grained stories. That's a possibility. Darwin... started out by saying, look, there must be some common principles at work here. My impression is that if you try to find the common principles, you have to extract so much from the detailed grain of the causal history that you end up with truisms, like there must be something in the environment, there must be something in the organism, or both.'

The assumption that Fodor is challenging is that natural history or biology must be more like physics than history. 'But suppose it's more like history than it is like physics?'

UPDATE: Blogging heads now has a commendably measured conversation between Fodor and Elliott Sober. The action is in the last 30 mins or so, and their debate turns on whether you think the probabilistic predictions from evolutionary theory (about, say, the spread of certain traits in populations) comes from the theory of natural selection, as Sober does, or rather is tagged onto the theory by smart evolutionary theorists, as Fodor argues.

In the same issue, the magazine also has lots on philosophy's efforts to offer practical wisdom. Julian is rather sceptical about this, resisting the attempt to judge philosophy instrumentally.

What I think he doesn't quite see is an alternative to philosophy as pure rational enquiry and philosophy as tips and tricks, namely philosophy as wisdom. This is a deeper understanding of an aspect of life - and even more interesting, a deeper understanding about what you don't understand about an aspect of life - both of which provide reflection on the art of living. It's what Aristotle called practical intelligence, and it's what I try to suggest Plato offers with respect to friendship, in my contribution in the magazine. A taster:

(Plato's) dialogue enacts the dynamics of friendship. A reader can’t help but examine the friendships they know too – learning about it in the process, not in abstract but from life. Moreover the elusiveness of a definition is a reminder that friendship is an I-Thou relationship, as it would later be described, one in which I encounter another. That can’t be tied down because it is a relationship that lives.

The meaning of a word is not what it refers to but how it refers to things. This is a relatively common distinction amongst philosophers, particularly since Wittgenstein, but is one often overlooked, and whose ramifications are extensive.

It's overlooked because it can seem unnecessary. When I say 'cat', I might point at her by way of denotion, and so it seems that the meaning of the word 'cat' is given by what I am pointing at. However, pointing itself is an action that presupposes much - that the extended forefinger indicates something in a particular direction, and then that what I am pointing to is my cat and not her brownness, furriness or purr. You must share those suppositions with me to share the meaning of the word.

So, when I say 'cat', it's how I am referring to something that conveys the significance of the word.

That words have howness, not whatness, might be at the heart of the reason why neurosceptics argue science will never explain consciousness. The thought would be that science yields explanations as whatnesses. The brain scan shows what neurons are firing, from which the neuroscientist infers what correlations can be drawn.

Consciousness, though, has howness. It does not know what red is - about 650 nm to science - but rather how red is as redness. Like words, which are its creation or discovery, consciousness is always about aboutness.

Seen Avatar? It is outstanding and astonishing. That's the first and last thing to say about it.

As to the politics, it's clearly about the environment, though I wouldn't be cheering if I was an environmentalist. The film offers catharsis for the ruining of the rain forest. It almost certainly says to viewers, 'you were moved, you've shown remorse - and now you can carry on as before, as it's only a fantasy movie.'

I felt that the 3D was a limited success. There is this strange layering effect it induces, which looks like a variety of hyperreality rather than the real world. My guess is it'll work well for fantasies, but not for other genres, where it'll be a distraction. Also, it's a strain on the eyes.

The thing that anyone interested in philosophy is bound to contemplate is the number of different, and incompatible, philosophies of mind the film incorporates. Cartesianism abounds, in the avatar bodies that must be animated by external minds. Computer, brain-centric models do too, in the 'plug and play' firewire with which Pandora's lifeforms come equipped. There're clear moments of panpsychism, via the comments about the energy that flows through all things. And there are hints of externalism, as contrary to the computer model, Jake Sully can't just be uploaded with knowledge of how to excel as a warrior, but he must learn it by being in the world. Others you spotted?