Defines objects by what they do, not what they are made of. For instance, a corpse is no longer a human because they seized all human functions already! And it also describes a specific software user, for instance ones that prefer no beautiful "modern" aesthetics (what it looks to be made of) in exchange for speed (what it does) because it is less laggy and energy-intensive for their computer! It is also a form of pragmatism, essentially.