To suggest that these relationships are causal does not involve a major departure from what we know already.  Within countries we know that all the components of our Index of Health and Social Problems are strongly related to social status: the further down the social ladder the more common they become.  The new part of the picture is simply that if you stretch out the social status differences all the problems related to social status become more common. Rather than postulating entirely new causal processes we are therefore only providing a bit more information about the relationships that have always been recognised.

People who have studied the graphs on this web site and in The Spirit Level carefully will have noticed that there is a clear tendency for countries which do badly on one outcome to do badly on others.  We show evidence that 10 or 12 different problems tend to move together. That implies that they share an underlying cause.  The association between inequality and our Index of Health and Social Problems is very close and no one has yet suggested an alternative. 

Lastly, as the different chapters in our book show, many of the causal processes leading from inequality to the various health and social problems are already known. For example, the effects of social status on health have been demonstrated among monkeys in experiments which kept diet and material conditions the same while altering social status by moving animals into new groups and the effects of chronic stress on the immune and cardiovascular systems are increasingly well understood.  Similarly, violence is more common in more unequal societies (where status competition is intensified) because it is so often triggered by people feeling looked down on, disrespected and humiliated. 

From time to time changes on income distribution may be triggered by new governments with different philosophies or economic theories.  This happened in a number of countries when monetarism and neo-liberal ideas became common during the 1980s.  Legislation was introduced to weaken trade union powers and changes in taxes and benefits were introduced which contributed to a widening in income differences.  However, although it can be said that a change in political and economic ideology contributed to widening income differences, there is no doubt that governments did not intend to weaken community life or to increase levels of violence, teenage birth rates, drug abuse or any of the other problems which go with greater inequality.  These were all unintended consequences of widening income differences. 

Nor can an increase in health and social problems be the cause of widening income differences.  As we have seen, a wide range of health and social problems tend to move together – countries which do badly (or well) on one outcome tend to do badly (or well) on others. If they were not all results of inequality but were instead separate causes of inequality, that would not explain why they move together.  Indeed it is not plausible to think that problems such as homicide, obesity and low standards of child wellbeing – which are all associated with inequality – could be a cause of it.

No. If you look at the graph in which all the separate outcomes are combined into one Index of Health and Social Problems (Figure 2.2 in The Spirit Level),  you will see that even if all the English speaking countries were excluded, there is still a powerful relationship between inequality and the index among the remaining countries.  The same is true of the UNICEF Index of Child Wellbeing.  A statistically significant relationship also remains between inequality and the Index of Health and Social Problems if you instead remove all the Nordic countries.  Indeed, the relationship is still statistically significant if countries at each end of the distribution – Sweden, Norway, Finland, USA and UK – are removed.  The association between inequality and social dysfunction cannot be explained simply by cultural differences.

People sometimes wonder whether the countries which do well are more homogenous and have fewer ethnic divisions than ones which do badly.  There are several points to keep in mind when considering this.  

First, an international study, which collected data on the ethnic mix in each country found that it did not explain the association between health and equality.  Interestingly, a very similar proportion of the population of Sweden and the USA are foreign born, and Spain is more equal and does better than its neighbour, Portugal, despite having a larger migrant population.

Among the US states income distribution tends to be more unequal in states in which a higher proportion of the population are African-American. One paper suggested this explained the relation between inequality and health.  Since then other papers have been published showing this is not so and a computational error was found in the paper which first made that suggestion.  In addition, in the more unequal states health is worse among both the black and white populations.  But migrant groups sometimes have unexpectedly good health.  In the USA, the largest group of migrants are Hispanic, predominantly from Mexico.  Although their levels of education and income are much like those of African Americans, for most outcomes their health is as good as that of the non-Hispanic white population.  That they do not seem to suffer the effects of their low social status is sometimes referred to as the ‘Hispanic paradox’.

However, insofar as ethnic divisions are related to inequality and may contribute to the effects of inequality, it is not of course skin colour itself – or for that matter religious or linguistic differences in themselves – which affect health.  Instead, they become important when they serve as markers of social status attracting stigmatisation, prejudice and discrimination. This means that rather than ethnic divisions involving quite separate processes from those through which inequality has its effects, they involve very much the same processes.  Whether the markers of social status differences are attributes of class alone or whether they include issues of language, religion or ethnicity, the underlying processes are basically the same. 

Rather than stimulating innovation and progress, great inequality wastes the talents of a large proportion of the population.  The evidence shows that it reduces children’s educational performance as well as reducing social mobility.  Economic studies of the relationship between the extent of inequality and economic growth rates have mixed results: most suggest that greater equality is beneficial to growth but a few suggest the opposite. As a check on how inequality might affect creativeness and innovation, we have now looked at the relationship between inequality and the number of patents granted per head of population. There is no tendency whatsoever for more unequal societies to gain more patent's per head than more equal ones. (N.B. This is a correction. Using published patents data that turned out to be inaccurate, we had previously stated that more equal societies actually had significantly higher patents per head).

The evidence suggests that the wellbeing of the poor is more closely tied to income levels than is the wellbeing of the better off. When parking fines or a washing machine repair make a major difference to a whole month’s budgeting and sometimes  lead people to borrow from loan sharks or fall behind with the rent, there can be little doubt that higher incomes would decrease the sense of desperation and hopelessness that are particularly common among the least well off.  

Not having a sense of being in control of things has been shown to be an important source of stress and harmful to health.  Inadequate incomes mean people face one crisis after another. As a result, family life suffers as financial issues become a frequent source of conflict.

No. The scale of income inequality is very different in different countries – and even in different states of the USA.  The more unequal of the rich developed countries (Singapore, USA, Portugal and the UK) are about twice as unequal as countries like Japan, Norway, Sweden and Finland.  There are also big differences in the levels of inequality in poorer countries.  Not only does the extent of inequality vary from country to country, it also varies over time.  Income inequality grew rapidly in Britain, particularly from the mid 1980s to the early 1990s.  The USA had an almost continuous increase in inequality from the mid 1970s to the early 1990s.  Graphs showing the trends can be found in the last chapter of  The Spirit Level.  Although income differences widened in many countries, they did not do so in all countries.  In the 20 years from the mid 1980s onwards, countries such as France, Belgium, Spain and Greece were among those which managed to avoid increasing inequality.

Governments in all rich countries control close to 40 percent of economic activity: they cannot avoid affecting income differences.  The increase in inequality in both Britain and the USA almost certainly reflects the neo-liberal economic policies of the governments in power. Differences in “market incomes” – that is income before taxes and benefits – can be reduced by strong trade unions, by minimum pay policies, by employee representatives on the board, by a public ethic intolerant of the “bonus culture” and so on.  They can also be reduced by taxes and benefits, particularly if more stringent action is taken to prevent tax avoidance. Other less direct influence on income differences include education policies and the management of the national economy.