SOMETIMES books, for good or bad, define ages. Will Hutton's The State We're In captured the hopes many people had before New Labour was elected. George Orwell's 1984 tapped fears of the Cold War and totalitarianism.
And in the midst of the bubble, Malcolm Gladwell's lightweight The Tipping Point told people change was easy, simple and all about stories.
The Spirit Level by Richard Wilkinson and Kate Pickett has reached these levels, but is a serious book by two epidemiologists. Its central thesis is that inequality hurts and that more equal societies work better for everyone.
It has been cited by David Cameron on the election trail, by Sweden's Social Democrat leader Mona Sahlin, and this week by a fawning Guardian editorial which claimed that "to emerge from stricken times without breaking Britain, The Spirit Level's inconvenient truths must be faced."
The Spirit Level has aroused significant opposition and even a counter-thesis, including The Spirit Level Delusion by Christopher Snowdon. John McTernan, fellow Scotsman columnist, and other New Labour advocates detest what they see as the demonising of their Camelot: Anglo-American capitalism with all its dynamism, inclusiveness and the meek of the earth making their way to our shores from far flung lands.
After years of the Thatcherite free market rhetoric - of trickle down, tax cuts and the Laffer Curve being cited as gospel - has The Spirit Level turned things round? Not surprisingly things are a little less clear-cut than the thesis put forward by the authors.
First, the central argument of the book for all its huge claims is actually unclear. Are the authors arguing that in more equal societies everyone benefits, or that on average everyone does better? There is a profound world of difference between "almost everyone" and "on average everyone". It is not possible to make the claim that everyone gains from greater equality.
Secondly, The Spirit Level makes sweeping assumptions about the place and cause of inequality across different societies and gives huge importance to the outliers. For example, the US is the most unequal wealthy society in the world on most indicators, Japan one of the most equal, while the Nordic nations do well on economic and equity comparisons.
Yet, it is almost impossible to compare these countries on equality; they are very different in their cultures, values and histories. Williamson and Pickett claim that "more equal societies almost always do better" - a universal, sweeping statement - which cannot be substantiated by most of their data.
Thirdly, the authors discount the possibility that the poorest in unequal societies have become detached from the mainstream. Isn't it possible in the UK and US that the poorest 10-20 per cent of the population have become detached from economic prosperity? The US healthcare debate reflected this concern.
Fourthly, inequality produces winners whose lives flourish and are not negatively affected by inequality - something the authors try to contradict. These winners might be few and far-between, but they exist and matter - from Chelsea FC to Tiger Woods to Tony Hayward and Fred Goodwin.
The last two points illustrate something Wilkinson and Pickett ignore, namely, the unequal distribution of the cost of inequality. Winners gain rewards; the poor are left with the disproportionate consequences of inequality. The Spirit Level in its search for a message for the majority of the population tries to deny this.
One of the central weaknesses of the book is the absence of the importance of politics. How did inequality rise in the UK and US these last 30 years? Wilkinson and Pickett dismiss it in half a page. They let neo-liberalism and free market fundamentalism off the hook on the basis that rising crime, violence and ill-health was never part of their script; but offer no alternative reading.
The Spirit Level yearns for "evidence based policies", yet, fails to recognise that "evidence" is never neutral, always about ideas and values. The book's success, itself a tipping point, taps into deep psychological yearnings and liberal guilt about affluence, inequality and the direction of our society.
Carol Craig in her recent book on Glasgow's problems cites The Spirit Level as proof inequality hurts and attempts to use its thesis as a way of understanding the city's inequalities, but like the authors never clearly defines what she means.
What The Spirit Level does not recognise is that evidence and facts will not defeat or roll back inequality. What has dramatically changed British and American society the last 30 years has been an ideology and a dogma which has resulted in the state of affairs and mess we are in. Governments, policy makers, opinion formers and media have gone along with and acquiesced in its assumptions. This worldview is oblivious to evidence and facts.
The Spirit Level has done us a public service, bringing a debate about the merits of equality and inequality to the centre of public debate in the UK and elsewhere. It is now widely accepted that GDP does not automatically equal progress, but the complex causal relationships are never fully explored by Wilkinson and Pickett.
Yet the book has become a new, intolerant orthodoxy which its followers believe in like a faith, tapping into their sense that something is wrong and giving them a moral purpose and superiority. Such people don't want a debate, but something new to blindly believe in: a kind of quasi-religion.
At the heart of The Spirit Level for all its confidence there is an unsureness about what to do next. In answer to their question, "what can be done?", the authors answer "the good society" and how employee ownership can lead to a "better society". Missing in all of this is anything about politics, ideology, the economy and how we deal with the elites who have gained disproportionately.
The Spirit Level is a manifesto not for new times, but a symptom of the age we live in: dealing with the debris and chaos of the last 30 years, while only having a vague notion of how we get out of it. That requires moving beyond liberal guilt and unquestioningly following anything, and embracing ideas, ideology, and in particular, difficult choices.