This has been my number one demon-question that has haunted me throughout my martial arts experience:
How far forward should we be in a front stance? So the knee is still behind your toes? Your knee is just over your toes? Or past your toes?
In the early stages of Hawaiian kenpo, I was told that in a bowstance, your knee should be over your toes so that if you look down, you can't see your toes (if I'm remembering correctly). I didn't question it much, and I think this would make for the knee being just over the toe.
Then, in tai chi chuan, is where I really ran into trouble. At first, I couldn't find a clear answer, and so began asking my teachers and training partners, and looking at pictures of tai chi chuan masters to see what they were doing. From pictures, I got a wide variety of answers, basically finding enough to conform to each of the three choices. The stances that were far over the knee looked a little too dependent on muscle strength and more committed than I thought fit with the ideals of internal Chinese martial arts I was aiming for. The forward stances that were far behind the knee looked a little too empty to me, as if the person is just standing there instead of being "involved" in their tai chi chuan. (However, this perception is potentially flawed in many ways when considering true tai chi chuan. Nonetheless, it's what I thought and felt.) But then the stances with the knee lined up with the edge of the toes looked balanced and strong enough for me. I began experimenting with my training partners and teachers, and we quickly noticed that if our knees were past the toes at all, we could be easily pulled over while practicing fixed-step push hands.
So there it was, the Golden Answer! You should always have your knee be lined up with your toes in a front stance all the time, because if you were over you were susceptible to being pulled over, and if you were behind your toes, you weren't in as strong of a stance you could be.
But then I started doing aikido in Japan. In one of the very first movements I learned where you do tenkan (tenkan undou?), a movement where you start in a front stance, step forward with your back foot and pivot to swing your other leg back, and back and forth thus alternating your front leg stance with each swing. I was mindful of my earlier found knowledge, and always had my knee perfectly in line with my toes. But from the very first second sensei saw this, he told me to lean forward. I hated it, and ignored it while practicing when sensei wasn't looking. The problem is being in a front stance is a regular thing in aikido, and we practice the tenkan undou every single night with pairs. For months and months, actually probably a whole year, every single fricken time, sensei kept saying, "Motto mae! Motto mae! More forward! More forward!"
Actually, the really frustrating part seems to be that there always seems to be a differing degree of leaning forward depending on the movement. When in your initial ready stance, hanmi, your posture, or kamae, seems that your knee should be behind your toe. When doing the tenkan undou, you should be past your knee. When practicing with a ken (wooden sword) or jo (short staff), you should be far forward(?) It seems to be different in every posture, and different every time I look and ask. The other night, I asked one of the senior ranking students about how far forward the knee should be, and he said forward enough so you cannot see your toes. Well, I go that far, and then everyone tells me to go farther. So that answer didn't help me much, except that it doesn't seem to have such a specific answer, and must be felt and adjusted appropriately to each situation. You may be wondering now, haven't I gone straight to sensei and asked this question? The answer is no, actually I haven't. I've thought about it a few times, but I just haven't had the perfect chance yet. Perhaps its something I need to keep working out for myself. Honestly, I envision being frustrated with another ambiguous answer.
Anyway, so what do I do now? Always motto mae. Nanto naku, I've changed, and now if I'm committed to action with an opponent, I love being more forward in a front stance.
Why have I made this change? Well ...
Perhaps we need to look at some misnomers I've had with my bias against the front stance:
First, I thought that it made me susceptible to being pulled over. Perhaps that is true, but if someone is really giving me a good pull, I'm not going to be able to nullify it just because my weight is back a bit. So, if I'm really being pulled, I should go with it, and go forward with a movement that can put me in the advantage and the opponent in a disadvantage. Perhaps this is one thing to consider: My earlier decision made in tai chi chuan was largely based on fixed-step push hands scenarios were one has to protect against the threat of small pulls to get you off balance, but this scenario does not mirror all movements in the martial arts, and cannot define all-applicable perfect stance.
Second, I thought being forward made it hard to evade to the rear. This may also be true. If you are in a rear stance, you can certainly move easier to the rear; but that's not the direction I usually want to go. After years of practicing, I've finally realized that by going backwards, you may have nullified an attack, but you haven't given yourself much of an advantage. Instead, I would rather move directly towards an opponent if he is waiting, or counter to the side while still moving forward if the opponent is initiating the attack. This is actually a misnomer I've had about aikido. I've thought that it is a reactionary, passive, evasive, and confrontation-avoiding art. Perhaps these adjectives can be used from time to time to describe motions in aikido, but so can action-initiating, aggressive, and invasive to a certain extent. There are moments of contact and times when you are pushing against an opponent in aikido, but only done so if you have the advantage; be it leverage, momentum, or a particular angle.
My third point is connected with the second, which is, leaning too far over the knee makes you only able to move forward effectively. Actually, though it isn't the best stance for moving back, I think it allows enough movement back for me considering it's forward advantage, which started being mentioned in the paragraph above. I want to move forward, take my opponents space, and deal with it however is most necessary. I can't help but think of Bruce Lee's philosophy in this question. Bruce Lee certainly favored a forward stance, and even advocated having is back heel off the ground so that his leg acted as a spring to further enhance his forward mobility. Certainly, Bruce Lee used techniques that were not only forward strikes, and did so sufficiently in his forward stance.
This question has haunted me ever since I stepped in the dojo here in Japan, but I've finally acquired enough legitimizations to convincingly practice the forward stance sensei wants me to. I think the largest motivation that has turned my opinion, is more of a "monkey-see, monkey-do" phenomenon. My sensei is the same height as me, and may be a few pounds heavier (due to a small pony keg he's working on thanks to a love of sake), and I would bet money I could outlift him in any excercise in the weight room, but he has a strength and power that absolutley dwarfs me. He practices with a great ferocity as well as softness, that is utterly dominating. When he does a technique on me, I go exactly where he plans for me to go. When I do a technique on him that isn't perfectly in line, I cannot go further without excerting all of the muscle strength I have to try and out-muscle him. This is not due to his muscle power, but the powerful stances and balance he has and uses in his techniques.
I may not have The Golden Answer to the knee question, but I have a shiny one that's keeping my attention now.