David Knowlton wrote:
you have to explain to the police why there is a person lying in the ground in front of you. (At my wife's school BOTH parties are punished when there is a fight; this is also true where I work - immediate dismissal)
I tend to agree that the differences in Aikido and other arts have more to do with spiritual principles or - at least - attitude than any physical ideas.
Your comment above put me in mind of a situation that happened with one of my students that illustrates a very important point of Aikido to me - the ability to deal with a fight without fighting. More often than not, IME, Aikido works best when the Aikidoka doesn't fight back.
My student - probably about six at the time - came to class one night with a story to tell me. I think his mother was more excited than he was. Some kids attacked him on the playground, he just turned and bowed and they all fell down. They got in trouble, he didn't. Why not? Because he was never fighting and it was obvious to the teachers that this was so.
That "shrugging the attack off" kind of thing is an important idea in Aikido, IMO, and one of the hardest things to master. But there isn't anything special about the physical principles involved.