OK I want to get to the bottom of this 'spiralling' issue but I have yet to even be convinced that there is a true disagreement in the first place:
Two people could argue about the color of a cloudless noon sky-- not because of any difference of experience, but because of word choice. How am I supposed to know if one of you is wrong about the color of the sky? (Of course, go look at it with you, but I don't think we've really hit the limits of a net forum yet).
Case in point, "linear." Dan and Mike both disagree with the idea of a foot, belly, and hand needing to be colinear. But still there's arguing.
Generally, the power from the ground goes up the legs to hips and dantien and then the shortest path to the point of application.
So Mike, you have described (in this very simple example) 2 line segments, (possibly 3 if we count a segment between hip and dantain) which are not necessarily colinear with each other. In fact those segments are anchored to certain points of the body in this description, meaning one could really put severe angles between them by moving into a certain shape. So for all this "linear" talk, you have in fact described:
-a series of connected line segments
-segments having end positions that are contingent on body shape
In essence: a force percept that can project linearly through the air while also being constrained (in some locations) to follow the shape of the body. The shape of the body is agreed to be curvy: we all agree that the human body wants to express spirals, as revealed in either relaxed movement:
[quote isn't working-- in the "what kind of spiraling does aikido have" thread, Mike points out that Ueshiba emphasized relaxation, a condition in which the qi naturally spirals]
Or in high-stakes sports:
[quote isn't working-- in the "what kind of spiraling does aikido have" thread, it was pointed out that in tennis, it is advised to pay attention to the spirals of the body's movement]
So even if this has nothing to do with chansijin, we have curves that describe movement of the body, and a force percept that tends to follow the body. In other words I can see how "linear" can sound wrong and in essence be pretty reasonable. If the human body moves in spirals when used most efficiently, and the body is made to cleanly express the ground's push continuously throughout
a movement.. I am not sure what the argument is anymore. Of course a force has only one magnitude and one direction. So it is "linear." But how you use it is constrained by the way the body moves (in a spiralling shape).
I think the basis for the disagreement is not coming through in the words here.