Principals of aiki will assist an individual in fighting off an attacker while on the ground
one is being physically attacked on the ground -in an attempted rape, no less - the only solution if one chooses to fight, is to devastatingly injure the other person.
One can go too far in the idea of non-resistance, restraint without brutality, etc. Osensei had a daughter. what she should do if being sexually assaulted, he would have suggested, pulling out long 4 inch pins that held a traditional hairstyle, and ramming it in the man's ear into his brain. (a traditional woman's self-defense tactic in Japan - not a product of my imagination).
Oh oh...! Another MMA/BJJ vs. Aikido immortal monster of a thread thing. Gotta love 'em
I think this unresolvable question will live on for ever until:
1. Someone bastardizes* Aikido successfully for MMA fights (*don't know if the word is not exceptable, no insult intended. I am not intending to be profane. But the word works well with being without parent connection. Pls. excuse it, if it's seen as profane
2. All those who take both MMA and Aikido, and lean more to MMA than Aikido realize the two are worlds apart. That each came into its own at different points in time and culture. One is an art and the other is a combative sport. MMA train for a sport fighting competition, Aikido was never intended to do that. The composite Aikido that does compete wasn't intended for an Aikido venue and not MMA. MMA wasn't around when that style of Aikido was created. Therefore, those who want to make a living fighting or enjoy fighting as done accordingly to MMA rules, do MMA. Those who are looking for something else who isn't about becoming a fighter, but other things go to Aikido. Not everyone wants to do a Hell's Kitchen because they enjoy cooking.
Now shifting gears. If in a real self-defense situation on the street there is a possibility the situation will go to the ground. But keep in mind where Aikido came from. It came from real combat tested martial applications that where effective in killing the other guy. Not from a sport where the loser walks away from a ring with rules, ref, and judges that has to be commissioned to take place, without a medical staff at hand. Aikido techniques designed from that to be use in a time and place when there was a shift in Japanese society, long before MMA. This means that Aikido does have validity in a self-defense situation both like Ellis and William has said. More than likely, depending on your training in either MMA or Aikido you are attacked on the street you are likely to have the advantage. And that is what it all comes down to anyway, where you take them to the ground, or it goes to the ground, or it can't
go to the ground or it doesn't go to the ground. The advantage I see Aikido has over MMA in a situation where you are standing is control, like using a come-a-long on a drunk.
The other thing I see like Ellis pointed out is the intensity of the situation being faced and using what ever you have because you are fighting for your life. I doubt very highly that if an Aikidoka happened to found him or herself on top of an attacker their instincts wouldn't kick in to "ground and pound." That is the natural instinct to punch viciously at the face of the guy on the bottom who was trying to kill you. In an intense life or death situation you don't what your going to do, or how you will react. Regardless of your MMA or Aikido training if you have a gun pointed at your head you might freeze, and lose blatter control.
MMA so specific doesn't train to deal with the high-pressure life or death victim situations. Aikido doesn't generally, but it is more adaptable to do so. There are a variety of techniques, and Aikido's techniques are combat life and death stuff. It is those techniques are not taught that way.
So there you go. If your an MMA and interested in proving MMA better than Aikido, in the house of MMA. If your an Aikidoka you probably don't care, cause that is not what your about. What really beyond the talk either is ever faced in a high-pressure life or death situation where your targeted as the victim. What really matters is you don't lose at any cost no matter what you do, whether it be Aikido, or MMA or what ever you need to do to get the job done . Isn't that what really matters instead of all the goating and posturing.