Re: causing no (serious) harm
basically, the attacker gets the same amount of "harm" as he/she invests into it.
the harder they come, the harder they fall.
aiki is just letting the attacker deal with his own stregnth.
having aiki is to remain a neutral factor in the situation.
its obvious the attacker wants to inflict harm.
so, aikidoka make it obvious he/she isn't going to fight.
i consider it an act of compassion to be able to damage an opponent, and not do it,while essentially showing the attackers that they are really attacking themselves. (literally and figuretivly).