Some definitions can be justified - for example, cats seem to be a discreet category in the real world, and thus a definition of the word cat must adequately describe this category and how its members differ from other things in the world. But when it comes to things like love, justice, government or art, these things are human constructs, and not some discreet entity in the world; so how do we create justified definitions of these terms? How do we decide what true love is, or what true art is, or what true justice or government is? We all have intuitions, but these intuitions change with time and culture, and people tend to bicker about the details. So how are definitions that do not apply to physical phenomena justified?