Why Shizentai?

Why Nihon Goshin Aikido Practices its Katas in a Shizentai (Neutral Stance) instead of in a Hamni Stance Like Other Associations

Professor Tomiki (the Founder of Tomiki Aikido of the Americas) once expressed the ideal state of mind and body in aikido as "Mushin Mugamae."

Generally, "Mushin" is the state of mind that can perceive everything around you; a condition of enhanced awareness. You are ready for any possibility. Sometimes, "mushin" is narrowly translated as "no mind" but that does not convey its meaning well.

The term "Mugamae" literary means "no posture" or "no stance" ~ the shezentai. Unlike in Nihon Goshin Aikido, Aikido of the Americas, United States Aikido Federation, Schools of Ueshiba, etc. (those organizations who trace their lineage to Daito-ryu Aikijujutsu through Morihei Ueshiba) assume that it will take years of dedicated practice before a student can hope to attain this enlightened state ("Mushin Mugamae") in which you can operate out of no stance. This assumption in place, the Ueshiba Aikido organizations believe it is therefore proper to enter the practice of aikido through a hamni stance (or other basic defensive posture). Then from this humble, set stage beginning, the student can endeavor to graduate, through years of training, to "shizentai" (natural posture), or "mugamae."

It is apparent that Shodo Morita completely disagreed with the notion of "advancing" to the point of operating in shizentai. In fact, all Nihon Goshin Aikido students are taught to defend themselves from a Mushin Mugamae, natural posture (no stance), from day one.

This is a major difference in philosophy, and becomes readily apparent in any cross training venue. If you plan to cross train, I believe it makes sense to understand the background of the stance debate.

Source: http://www.aikidoamerica.com/html/principles.html