PEI - thanks for your clarification regarding Post #34. Below is my attempt to address your question with regard to 737. As always, if there is something I have missed please let me know.
737 pitch control involves an all-moving horizontal tail (stabilizer), a pair of elevator surfaces mounted on the trailing edges of the stabilizer (left and right), and a pair of elevator tabs attached to the trailing edge of each of the elevators. On some airplanes control tabs are used to drive a trailing edge control surface with the tab driven but the larger surface floating. That is not the case with the 737. The 737 elevator tabs are directly geared to the elevators themselves. Geared tabs that move in the opposite direction as the larger surface are called "balanced" as they generate hinge moments that subtract from those of the larger surface thus the total force required to move the elevator and tab is less. Conversely, tabs that move in the same direction as the larger surface are called "unbalanced" as they increase the force required to move the surface against the airflow past the horizontal tail. Interestingly, the 737 across its run of derivatives and in response to flap configuration and hydraulic power availability uses its elevator tabs as either fixed (no motion relative to the stabilizer), balanced, or unbalanced. The details of when the tab behaves in these three different manners is beyond what I want to get into here.
The 737 (as with all of Boeing's commercial transports) uses pilot controller position based control to command the associated control surfaces when flying manually. (I acknowledge that the autopilot does provide a Control Wheel Steering mode, but let's leave that beast out of the picture here.) The 737 elevator (and thus its geared elevator tab as well) are driven by the position of the elevator aft quadrant. If one 737 column is jammed, no amount of force on that column will result in any elevator motion provided that jammed column remains stuck and does not move. Motion of the other column will result in limited motion of the elevator aft quadrant and thus some elevator control. A key element in providing this mitigating control path is that the mechanical cables connecting the elevator aft quadrant to the jammed column are not infinitely stiff such that when subject to force applied by the crew on the column that is not jammed the cables on the side with the jam will stretch allowing elevator aft quadrant motion.
The 737 is in pitch trim if the net pitching moment for the full airplane is zero with no force applied to either control column. There will be only one stabilizer position that achieves pitch trim at the current flight condition including thrust setting, flap position, and all other variations that generate pitching moment. If the stabilizer is not at this trim position, the airplane will experience a pitch acceleration / rate unless the elevator is positioned so as to provide the needed pitching moment balance. The pilot task is to position the column as needed to control pitch attitude and through that other response parameters such as altitude or speed. Stabilizer trim is to be used (when available of course) to relieve steady column forces to allow the pilot to reduce workload and to preserve available control power in both the nose up and down directions for subsequent maneuvers or disturbance rejection.
I must admit that I get a little lost trying to follow the thought process of the last couple of paragraphs of Post #34. I don't agree with the notion that the pilot has to form a new model of how the airplane responds depending on the trim setting. The incremental response to incremental pitch control inputs from the point of pitch equilibrium (be that trimmed with zero column force or holding a steady column force) is essentially constant. There will be variations in incremental response with weight, CG, flap, and speed, but not with changes in pitch trim.
Hoping this helps,
FCeng84