Moral Foundations Theory is pioneered by psychologists Jonathan Haidt and Craig Joseph.  At its core is the idea that there are a set of distinct and fundamental building blocks that can be used to describe moral behaviour.

There are 6 distinct moral foundations that influence moral behaviour :

1. Care/harm for others (think – parental care)
2. Fairness/cheating (think – mating strategy -> Maynard-Smith’s ‘sneaky fuckers’)
3. Liberty/oppression (along the lines of appetite for change, for the new)
4. Loyalty/betrayal (along the lines of group altruism)
5. Authority/subversion (think – eusocial tendencies)
6. Sanctity/degradation (think – cleanliness as a virtue)

Contrary to expectations, weightings for each of these 6 building blocks across large groups of people are not randomly distributed. When the presence of these moral building blocks is tested through questionnaires people tend to fall into a small number of distinct groups.  The major liberal & conservative political groups show distinct differences in the weightings they attribute to each moral foundation.  People with strongly liberal views heavily weight the 1st three of Care, Fairness & Liberty while those with conservative views tend to weight all equally.

That individuals attribute different weightings to each of the moral foundations also means that their reasoning in evaluating moral questions will be different leading to different expectations and outcomes.  The implication being that for individuals within the same group understanding the reasoning behind a moral decision will be straightforward. While for individuals from other groups with different weightings will find the decision confusing and indeed irrational.  Where society is made up of large heterogeneous groups with distinct differences in moral foundations and reasoning there is the potential for polarization and serious conflict.

The question then becomes: why do we see this level of heterogeneity of moral decision making type in societies rather than a random distribution?  Haidt et al. take the view that it is evidence of evolutionary ‘group selection’.  However different moral foundations in decision making is more likely to be an example of a behavioural polymorphism similar to blood-type biological polymorphism. The reason for different blood types has to do with the contagion dynamics of infectious diseases. It doesn’t pay for any one particular blood-type to become outright dominant as this would increase the risk to these individuals by increasing the frequency of contagion.  The result is that each blood-type is more susceptible to a particular type of disease while the other blood-types are more resistant to that disease.  The resulting evolutionary dynamic is balancing frequency-dependent selection where the ultimate cause is a reduction in extinction risk due to disease pressure .

Similar to blood-types, moral decision making types may cluster due to heritability and display histology-like incompatibility.  The existence of these different moral decision making types, from an evolutionary perspective, may also be due to a similar balancing frequency-dependent selection dynamic.  A society that is too conservative becomes stale, while a society too liberal descends into chaos.

This raises a new set of questions: What is the selection pressure driving this dynamic? Can the selection pressure be measured?  What are the proximate and ultimate causes?