The question is purely theoretical as I'm not aware of a solution to do this, but I have been thinking about what really need to be at a societal/cognitive level to tackle humanity issues such as conflicts/war.
I reckon many problems rise for the lack of tolerance due to a lack unerstanding of each other experiences and thinking (somewhat related to
the Theory of mind and Mirror neuron).
What will be the result of:
Increasing people's empathy?
bonus: Decreasing said empathy?
Backing your answer with sources and articles is a plus.
Increasing empathy would lead to a slow down in technological advancement as conflict is a major driver of new tech. With increased empathy conflict would occur less often due to being able to "Put ones self in another's shoes". Obviously this would depend on whether mankind is more motivated by empathy or greed.
Decrease in empathy would lead would lead to the rise of greed and violence to an unheard of level. The strong are the victors would become the norm in this type of world.