Well, I'm not intentionally trying to work with anything like a mathematical system. My claim was just that if by 'in reality' we mean 'referring to basic material objects and their motions' then we loose the ability to claim any explanatory priority between facts like 'X carries Y' and 'Y is carried by X'. Y didn't just get itself carried, X had to come along and carry it. X is the cause of Y's being carried.

But all that hinges on convincing you that there is some such explanatory priority, which I haven't done. I think perhaps my argument isn't very good. Thanks for the discussion, at any rate.