Fairness comes in different varieties, which may work together:  



Natural selection is relative.  



Fairness motivates cooperation  

Fairness and cooperation reinforce each other.  Cooperation may be described as what you put in to a situation; fairness refers to what you get out of it.  If people are treated fairly (whatever that means in the context) then they are more motivated to cooperate.  

In modern “primitive” societies of hunter-gatherers, there is egalitarianism (a very flat power structure with all members of the group contributing to decisions) and distribution according to need, so that all members of the group are cared for.  

Our nearest relatives, the other great apes, do not share like humans do; typically, high-ranking individuals dominate the proceedings and eat first.  It is thought that egalitarian sharing in the human way evolved because we started scavenging and capturing large prey animals where there was a lot of meat to go around and cooperation was necessary to secure a carcass or kill the prey.  



Perfect Compassion, justice and rights


When you act, each person affected by your actions is to receive the maximum benefit and minimum harm available to them.  

Perfect Compassion  


Each person is valuable in themselves because they are a self-generating source of flourishing.  

Perfect Compassion dictates to respect the individual and is a formula for fairness, i.e. justice.  

Respecting the individual means to respect the dignity of the individual – to respect their right to be treated fairly.  

Rights are given by others and asserted by the individual.