Haidt, Jonathan (2005). The Happiness Hypothesis: Finding Modern Truth in Ancient Wisdom. Basic Books. ISBN 0-465-02802-0.
Haidt, Jonathan (2012). The Righteous Mind: Why Good People Are Divided by Politics and Religion. Pantheon. ISBN 978-0-307-37790-6.
The six foundations
Care: cherishing and protecting others; opposite of harm.
Fairness or proportionality: rendering justice according to shared rules; opposite of cheating.
Liberty: the loathing of tyranny; opposite of oppression.
Loyalty or ingroup: standing with your group, family, nation; opposite of betrayal.
Authority or respect: obeying tradition and legitimate authority; opposite of subversion.
Sanctity or purity: abhorrence for disgusting things, foods, actions; opposite of degradation.
Researchers have found that people’s sensitivities to the six moral foundations correlate with their political ideologies.
While all three of the political camps studied by Haidt are sensitive to the Fairness foundation, progressives are particularly sensitive to the Care foundation, libertarians to the Liberty foundation, and conservatives roughly equally sensitive to all six foundations.
According to Haidt, this has significant implications for political discourse and relations.
Because members of two political camps are to a degree blind to one or more of the moral foundations of the others, they may perceive morally-driven words or behavior as having another basis—at best self-interested, at worst evil, and thus demonize one another.
Further research has shown that while members of all ideological camps have difficulty understanding others, conservatives are measurably better at understanding the point of view of progressives than vice versa, presumably because conservatives operate in a six-dimensional moral matrix that contains all of the progressives’ dimensions.
Researchers postulate that the six moral foundations arose as solutions to problems common in the ancestral hunter-gatherer environment, in particular inter-tribal and intra-tribal conflict.
The three foundations unique to conservatives (Loyalty, Authority, Sanctity) bind groups together for greater strength in inter-tribal competition; the other three foundations balance those tendencies with concern for individuals within the group.
With reduced sensitivity to the groupish moral foundations, progressives tend to promote a more universalist morality.
In attempting to show which moral matrix is "correct", progressives and libertarians may argue that the six moral foundations arose in a now non-existent tribal environment, and their evolution lags behind modern conditions, with larger-scale cities, countries, and supranational unions.
Conservatives may counter that human beings remain cognitively designed for life in groups whose size does not exceed Dunbar's number, and that it is wishful thinking to expect group competition and conflict to disappear in the foreseeable future.