The Spirit Level authors have given an answer to the critique (in Swedish). It is extraordinarily dishonest:
1. They still stubbornly maintain that their book demonstrates a relationship between inequality and life expectancy. Most of their text consists of attempts to confuse readers by pretending it has to do with the choice of country or the choice of inequality measure.
This is simply a lie. Regardless of the choice of measure (UN gini data, OECD gini after tax and transfers, UN 10/10 ratio) or the choice of country (28 OECD, 21 OECD, 21 OECD plus Singapore and Israel) there is no relationship between life expectancy and inequality that is statistically significant at the 5% level.
End of story.
Writing "Vi har ingen anledning att anta att en dataserie är att föredra framför en annan." (we have no reason to believe one data-series is better than another) is irrelevant, since both data-series show that you don't have a statistically significant relationship!
Who are you trying to fool with this silly game?
The refusal to simply admit that they have no robust evidence, despite the fact that they don't have a statistically significant relationship in any(!) of their specifications shows these people are not following academic standards.
2. They try to get around the fact that they have made claims they did not have scientific support for ("inequality kills") by saying that other variables in their book are statistically significant. This is just childish. If you make 5 claims, 1 of which people object to, it is not an answer to defend the other 4. This is not how serious debate is done.
3. They still claim their book demonstrated that inequality leads to lower mental health and lower innovation, even though it has been demonstrated that these two variables have no statistically significant relationship with Gini. I assume their silence means they have no answer.
4. They repeat the claim about US states, even though Deaton and Lubotsky (2002) have demonstrated that these results disappear when controlled for the demography of the states.
5. They constantly refer to two studies, as external evidence for their claims. They do not mention that one of these two studies (the meta-study with almost 200 studies) is done by themselves(!), and has very little credibility for the story they are trying to sell. Another sign of dishonestly. The readers of SVD have no way of knowing this. The other study is of 28 papers, not all of whom are significant.
More importantly, these are not the gold-standard surveys of the literature. They are not chosen because they have more scientific weight, they are chosen because they confirm their story.
The most reliable survey-article of this field is written by Princeton professor Agnus Deaton, one of the leading health economists in the world, in the Journal of Economic Literature, the most prestigious journal for surveys.
Deaton concludes that "it is not true that income inequality itself is a major determinant of public health. There is no robust relationship between life expectancy and income inequality among the rich countries, and the correlation across the states and cities of the United States is almost certainly the result of something that is correlated with income inequality, but is not income inequality itself".
To simply ignore the prevailing view in health economics about the relationship between income inequality and health is dishonest. Pickett and Wilkinson are betting that their audience are unsophisticated, and unaware about the scientific debate. They are trying to deceive the public, to give their political beliefs about inequality and health the aura of agreed upon science .
Pickett and Wilkinson are abusing their positions as academics. They should spend more time doing empirical research and convincing health economists of their claims, instead of trying to deceive a trusting Swedish public to sell books and gain fame and acclaim.