Rob has an excellent, reasoned comment on my ongoing discussion of knife technique in aikido. he makes the point that he essentially wouldn't want to go empty handed to a knife fight. That he'd rather have a knife (a tool). Too true. But I think there is an underlying misunderstanding of the role of the knife in aikido training in general.
Tomiki, when he started teaching aikido, put a foam knife in the hand of the attacker. Why? Some people say it was to facilitate competition. That's nonsense. He could have just as easily devised a competition ruleset with the attacker doing lunge punches. Some say that it was to preserve the budo spirit. I find that shaky too. If he's wanted to develop a traditional samurai-type sport he could have had them wearing kendo armor and defending against bokken or at least swinging foam bats. So, what does the knife do for us?
The obvious answer is, "We learn to defend against a knife." Well, that's the biggest load of malarkey yet. The knife has evolved over the course of thousands of years as the best weapon around - even surpassing the firearm for general utility. Knives cause gruesome, debilitating wounds even when they are not fatal.
Now, I'm biased. I'm not a fan of the Tomiki tanto randori methodology. From what I can see from what little I've watched. About the only thing that anyone has ever learned from competing against a foam knife is that if you take two relatively equally trained aikidoka and give one a knife, he will almost always win (see the video below). The knife is simply that big an advantage. Sure, in tanto randori, someone is occasionally able to knock the knife guy down, but it is almost never via clean technique and it is almost always at the cost of being cut many, many times. So, how do they balance that huge advantage of the knife in randori? They only score the attacks in which uke stabs moving forward with decent balance and they specify that the knife must enter tori's torso at nearly a 90 degree angle. Basically you can only do zombie stabs (albeit fast ones). But this is NOT a rant against tanto randori players. If you want to practice that way it's no skin off my back. I'm trying to get at what is the role of the knife in aikido?
In my opinion, the only reason we practice against knife attacks is in order to learn to deal with being totally outclassed. It doesn't really provide much incentive to test yourself against those that are weaker than you - you never have an incentive to get better. But if you give even the most inexperienced player a knife then all of a sudden everyone gets the point that everyone is potentially dangerous. With the knife we can see how we stand up in the absolute worst of situations, and that is incentive to improve. We learn that we have to treat everyone the same - as if they are so awesomely dangerous that they totally outclass us.