You must accept that your adversary is rational if you aim to avoid nuclear war because if you believe that they're mad and can't behave rationally then you have only one logically-consistent option remaining.
> You must accept that your adversary is rational if you aim to avoid nuclear war
In practice, humans are neither entirely rational nor entirely irrational. Humans occupy different positions on this spectrum according to genetics, culture and circumstance.
If we want to avoid triggering escalation events that may lead to an eventual nuclear episode it seems sensible to avoid certain emotionally-charged and chaotic situations such as having the armed forces of nuclear-armed states or their close allies in direct combat with each other.
