My perspective is the optimistic religious rationalist one.
We are utilizing what understanding has accrued over the course of many human worlds to bring about a Global Reconciliation.
The gurgling cultural certainty is one of "Conflict Theory", with our current status as the oh-so-traditional canary in the coalmine showing the outcome of this (frankly Aryan) Theory.
It is that there is only so much to go around (from lebensraum to status) and so whichsoever side on whichsoever day has the more popular argument, or more powerful guns, can/may/shall vanquish the other and drive them unto destruction.
My own presumption is called, "Mistake Theory", in the sense that I believe that humankind in general, and individuals in particular just... make mistakes.
Either because we are after all, just clumsy humans, or because we inherited some massive misunderstandings from the past.
More plainly phrased: It is nearly always the case that both people, and peoples, are simply mistaken.
I believe that 99.99% of human beings just want to live as long and as happily as possible and that through the use of friendly discussion and reason we can get over nearly all of our primary misunderstandings large and small.