Situation A) Sandpaper Y and sandpaper Z are rubbing against each other, producing heat. Both A and B are moving equally fast and forcibly as is possible.
Point 1) It would be absurd side with Sandpaper Y and say Sandpaper Z is the sole, or greater contributor to the heat.
Point 2) The opposite, naturally, is equally absurd. To side with Sandpaper Z and say Sandpaper Y is the sole, or greater contributor to the heat.
Situation B) Sandpaper Y and sandpaper Z are rubbing against each other producing heat. This time, Y is moving as fast and forcibly as possible, while Z remains completely still.
Point 3) Point 1 and 2 still apply. But also to say that Sandpaper Y is contributing more to heat production, is equally absurd. This applies to all possible the situations between Situation A and B (meaning the opposite situation B, and situations where Sandpaper A and B move all the different possibilities between they two extremes). More or less heat can be produced in all these varying degrees and possibilities of force and move, but never could it be said one piece was more responsible for any observable difference.
I think most of us see that this is absurd, by a kind of a natural intuition. Explaining why is less obvious, but here’s how I see it. Perhaps a starting point is the fact that both pieces of Sandpaper are required to produce the heat. Even if one of the pieces does not move, despite its stillness its is responsive by virtue of being there. By being responsive as a surface to all the varying speeds and forces the other piece is moving with. More or less movement from each side doesn’t mean one side is involved more or less. The more one moves, the more the other is relatively still? It kind of contributes in its stillness.
Further despite there being different pieces of paper logically it wouldn’t make sense to choose a side in a phenomenon that necessarily requires the two. In a sense there are not really two in the sense of producing heat, there is one, they go together always.
Few final points;
I don’t know if the use to speed and force are the correct words for what is happening, it’s just to say they move in a certain measurable way.
I don’t know but maybe there is a way, probably not in this example, but how one side counters the other to produce less heat. Negative feedback?