You can determine what objects can do because they are particular expressions of a single substance. Particular objects are known by the way they act in the group of interconnected objects that make up reality.

@Daniel Unuagbon

Harman's answer from a Spinozist perspective is consistent; however, there is the danger of 'overmining' from the standpoint of OOO (overmining: reducing objects to relations within a pre-given substance). To Harman, objects are never entirely exhausted by their interaction, nor exploited by a deeper substrate, as such there remains an irreducible core-the 'withdrawn' core. Hence, while we can witness objects interacting within networks, the fullest capacities of an object--what it 'can do'--cannot be exhaustively determined.

Ok thanks.