Form and Function
The term 'kamae' is used in Yoshinkan dojos to refer to the basic standing position of Aikido, as it literally means 'basic stance' in Japanese. It is a fundamentally important concept in our Aikido, so much so that it is probably the single most common commentary or feedback received by students: "Come to kamae", "Make a strong kamae", "Maintain kamae", etc. Though it seems like a simple word, it actually embodies a set of deep principles and theories found at the heart of Aikido.
These are based on the physical properties of the shape that this body position makes, a deceptively challenging shape to maintain. In addition, its effective use by a focused mind is a complex task, not in the least because our own bodies and minds, and those of our partners, are complicated things. Only through continual training can we acquire natural and automatic positions that harness these physical properties embodied in the techniques, most central of which is this body position concept, 'kamae'.
The kamae position closely resembles an empty-handed version of some of the forward-projecting, sword-wielding postures found in many Japanese sword schools. The empty hands move in unison, often in curving arcs and cuts, a strong center line and point are maintained, and a powerful connection is created between where the imaginary sword is being held (or to the point of contact with uke or an attacker) and the ground. In fact, all Aikido techniques can be performed, virtually identically, regardless of whether you, your uke, both or neither, have swords: the kamae and body movements are the same.
Kamae is not simply a stance in the sense of making your body look a certain way, although this is how one initially develops the position: through copying, or feedback from, an instructor. What is important is how it feels, or more directly, the physical properties it embodies as it interacts with uke or a violent force. To be effective, it must be based on sound theory rather than aesthetics or dogma.
A theory of stances should be able to do two things: to identify the goals of a good stance, and then to describe how best to achieve these goals.
First of all, of course, a good stance must remain just that: standing; i.e. it must remain stable and in balance, and be able to move when and where you want it to. This is true of any standing position, of course, especially so when engaged in a violent altercation. Aikido is, however, both a martial art , as well as a philosophy, one that says that it is more important to end a fight with no losers, than to win a fight. An Aikido stance must therefore be effective for less aggressive, less strong and smaller people to successfully engage with and control bigger, stronger or more aggressive people.
In fact, the foremost practitioners of Aikido, at any given time, tend to be small, frail elderly people, who, while some may not be able to lift a large bag of groceries, on the mats are still able to send groups of sword-wielding, attacking black-belts flying around like bowling pins. This suggests that power in Aikido comes from somewhere other than size and brute, muscular strength. Understanding and practice of kamae will develop natural body positions that achieve those goals.
Obviously a good stance must be able to sustain large amounts of force: both to absorb a great deal of energy, as in when blocking attacks, and to deliver it when taking the attacker down to the ground. Though high-level Aikido practitioners can make an attacking person collapse with barely a touch, they can also make an attacker feel as if they have run into a brick wall.
So we can ask ourselves, "Where does strength come from?". The commonplace view is that it comes from the force we are able to generate with our muscles. Stronger muscles equals a harder punch, stronger block, etc. But imagine a situation where a person was standing on a super-slick surface of ice, say a polished frozen lake, and they were pushing someone else standing on the shore, on firm ground. Obviously when the first person pushes they are just going to send themselves sliding backwards. And if they push even harder, they are just going to slide that much further backwards. In the inverse, if they were having a tug-of-war with the person on firm ground, they would find it impossible to win, nearly regardless of the strength, size or weight of the person on firm ground.
Power through Physics
This suggests that the amount of force someone can apply is dependent not primarily on the strength of their muscles, but rather on the amount of friction that they can bring to bear on the ground. How strong is their connection to the surface they are standing on? This is the fundamental principle embodied in kamae: to maximize connection with the ground, and then to align the body so that it can be channeled into one point at a desired place and time. (The other side of Aikido, of course, is the concept of 'blending', wherein the focal point of kamae is brought in perfect timing to a place that unbalances and topples the attacker. But that is for another lesson.)
People naturally use this concept when necessary in everyday life, for example when bracing against a door, leaning their bodies when the bus or train comes to a sudden stop, the position someone adopts in a 'tug-of-war' contest, etc. This is also the physical principle embodied in the inclined plane, the same principle as at work in kamae. It can be seen in things like door-stops and braces: the more pressure that's applied to them, the more are they pushed down into the ground, the stronger the friction generated, and the less likely they are to budge.
A similar principle is at work in architectural features such as the arch or the flying buttress: the load is transmitted down into the ground. Kamae is a stance that first aligns the body so that force can be channeled through it. It then moves the center of gravity forward, using the same principle as an inclined plane. When force is applied to it, or it is used to apply force to another body, the entire form is used to connect to the ground, focusing the force of gravity on a desired application.
This takes only the muscular strength required to maintain a position, a good workout in itself initially, but one that becomes quite relaxed through training. Constant training develops the technique required to maintain proper kamae and to move around as necessary while still retaining the desired properties.
Kamae can be thought of as an idealized body position that would maximize the desired properties of connecting to the ground, and channeling force. It is an active process to maximize alignment and unification of the body, either while balancing on one's own or while moving with a partner, and to remain grounded throughout.
Kamae: Stance Training
Kamae can also be thought of as a training exercise to develop the above properties. The kamae principle has something to say about the positioning of every part of the body. Initially, the way of training for it is to emulate the "ideal shape" of kamae, for example as demonstrated by instructors in class, or as shown in texts or this guide.
The immediate challenge is getting it to hold together and in balance, through moving into kamae and basic movements. As you continue to practice Aikido in general, and kamae specifically, you will begin to develop sensitivity to the flow of force between the point of contact with your partner, through your own body, and into the ground.
This is done with repeated training with partners in basic movements and basic techniques. The physical 'logic of kamae' becomes apparent, and the student should endeavour to simplify and make consistent their basic form and movements. Often bad habits learned in kamae have a great impact on limiting aspects of all techniques. An Aikido student will do well to continually practice a basic and proper stance, and to maintain basic form in all their movements.
Eventually, the senior Aikido student will develop a form of kamae that is their own, suited to the particular features, strengths and weaknesses of their own bodies. They should still strive to study basic forms, however, and should maintain the ability to teach and exemplify basic positions.