Is there a name for skepticism about the existence of categories (or properties) and objects that the mind may create to classify the "real world"? In other words thoughts, concepts, and so forth may conveniently classify the real world and help us predict things but they are only representations of the real world constructed from any sense data that we receive. It may correspond to objects in the real world but it is one step removed. So in this sense they do not exist (or rather, this position defines what exists to be everything outside the mind).
For example, the object tree only exists because human minds are calling some entity in the real world a tree. But if there were no human minds at all there would still be the thing we call a tree, it just would not have an actual name or identity at all. It would exist independent of human thought. Extending this, mathematical objects do not exist either but may be considered a model for the real world insofar as it reliably predicts our interactions with it.
Is there a version of this kind of position (more well-formed than my description) that describes this kind of view? The closest I can think of is perhaps a form of Platonism and sort of physicalism which acknowledges that we cannot know things-in-themselves ("real world"). It is opposed to solipsism or subjective idealism.