The following post by John Driscoll is excerpted from a thread currently in progress in the Aikido Journal forums titled “Ushiro waza”:
Why is it that uke starts attacking in front of nage when uke’s intention is to grab from behind?
“I would argue that starting from a static position with uke behind tori (shite) is the simplest way to teach ushiro waza, not having someone deal with the complexities of closing maai, trapping hands, etc.
“Consider the environment and times from which Aikido evolved for a probable explanation for the attack scenario of uke initiating a rear double hand grab from the front.
“I don’t normally like to go into these areas on a public forum, but have you considered the basic script of an assassination involving two attackers and edged weapons? Attacker #1′s mission is to take away the victims ability to defend himself, while attacker #2 delivers to the fatal attack. The simplest and most efficient is two attackers approach from the front, probably somewhat staggered. As attacker #1 comes even with the victim on the same side as victim’s dominant hand, the attacker grabs the dominant hand and pivots behind the victim, drawing the victim’s dominant hand and arm behind his back, and securing the victim’s non-dominant hand and arm. The victim is now virtually defenseless, with his entire front torso exposed. All that remains is for attacker #2 to deliver the fatal attack. I’ll leave the details for that to your imagination.
“If you analyze the sequence in the initiation of a rear double hand grasp from in front, you’ll notice it tracks with the assassination scenario. You’ll also notice that in Aikido most of the responses to a rear double hand grasp attack results in the attacker positioned between tori and a second attacker. Let’s face it, in a knife fight someone is going to get cut and it is much preferred to use one of your attackers as a shield to absorb the slashes and thrusts, rather than trying to evade the attacks, and to create an opportunity to run like hell!
“To answer in advance comments regarding attacker #1 lying in wait in some alcove, doorway, between two automobiles, etc., and grabbing the victim directly from the rear – it doesn’t work in the real world with anyone who has any training. Lying in wait works well with someone preoccupied or otherwise not alert, but not with anyone who is alert and/or trained. Because, as an alert individual begins to pass attacker #1 wherever he is lurking, he’ll pick the attacker up in his peripheral vision. At which point the potential victim’s fight or flight kicks in.
“I throw this out for discussion.”