The later Mohists taught that knowledge came from three sources: (1) hearsay, (2) personal experience, and (3) explanation (by inference or reasoning).
They also named four “objects (applications) of knowledge”: names, things, matching name with thing, and acting (responding appropriately to a thing according to its name).
The later Mohists felt that one needed to know how to use names in this way (matching names to things and actions) to make distinctions between those things.