To have an sensible world-view through which I can act, predict and communicate to live even the most mundane life, I have to look at the world as somewhat stable and regular, with regular and predictable connections between different situations, And as a perceiver and communicator I have to be able to distinguish between different things in shared experience, to identify those items, and to generally refer to them and describing them.
Any perceptual judgment is inside this system and assumes it. In saying 'This is a table', I am implicitly claiming that here in my perceptual environment is a spatio-temoral continuant, with all that that implies, and that I have perceptual access to it.
I am explicitly claiming that this object is to be classified according to the everyday procedures for sorting objects based on my interest. And this would be impossible without assuming the system.