We had thought income effects are small because we were looking within
countries. The GDP differences between countries are enormous, and
highly predictive of differences in life satisfaction. In a sample of
over 130,000 people from 126 countries, the correlation between the
life satisfaction of individuals and the GDP of the country in which
they live was over .40 – an exceptionally high value in social science.
Humans everywhere, from Norway to Sierra Leone, apparently evaluate
their life by a common standard of material prosperity, which changes
as GDP increases. The implied conclusion, that citizens of different
countries do not adapt to their level of prosperity, flies against
everything we thought we knew ten years ago. We have been wrong and now
we know it. I suppose this means that there is a science of well-being,
even if we are not doing it very well.
Here are Kahneman’s full remarks. He also presents a more complete theory of happiness, namely that is determined by basic personality type and which activities you are able to do during the course of your day, the latter being a function of wealth. That excerpt is from this post by Arnold Kling, on how people have changed their minds, read this one too. Here is the core source, highly recommended, it is one of the best hour-wasters you will get this year.