In the illustration below
Panel A ,The man on the left ,without provocation attacks the other man and kills him.Ethically this is the lowest level of the four levels.
Panel B, the man on the left has not directly attacked the other man,but has provoked the other man to attack him.When the other man attacks he is killed.While the first man is not guilty of launching the actual attack he is responsible for inciting the other man to attack.
Panel C, the man on the left neither attacks nor provokes the other to attack.But,when attacked he defends himself in a subjective manner,i.e.,he takes care of only "number one," and the other man is killed or at least seriously injured .The man still standing is neither directly or indirectly responsible for the attack.However his manner of protecting himself resulted in the destruction of the other man.
In panels A ,B, and C- the results are identical a man is killed.
Panel D, we have the ultimate in ethical self defense.Neither attacking nor provoking an attack,the man on the left defends himself in such a way,with such skill and control that the attacker is not killed,not even seriously injured.
Panel D,This is the goal of Aikido,this requires skill: the result of training in the technical art of Aikido and requires ethical intention,the desire to defend ones self without hurting others.