Nash think about it like this, for a moment:
Rational thought, and irrational thought.
Logic, causality etc for the first, poetry, emotion and all derivatives in the second.
If you take two systems and give each different operating systems, you most likely won't get indentical outputs from them, and if you did, it wouldn't prove they are the same ( we know this, we defined them as such).
So if any two people are not the same down to each atom, they can't have the same lives or points of view or taste etc. This lets you deduce they won't have anything further up the fundamental scale in common. So if you are from one tribe and meet someone from another that's across the planet in a completely different climate, you most likely won't "get" what the other is saying.
Like in almost every conflict so far, Irak-US, Ireland/UK, Christianity/Islam, Koreans/Japanese, your neighbour/you, alpha male/subordinate male, whatever.
None of this is new and is probably taught in any introductory philosphy class, but it's the basis for IRRATIONALITY not being a viable system of civility.
Which doesn't mean it must be erradicated. It's flawed for the purposes in question and shouldn't be ignored as such, depending on the level of tolerance for error/conflict/whatever.
