Ideally, the definition of hate will result from a complex negotiation between stakeholders in society, just as we draw a line on who counts as an "adult", what counts as "self defense", and what counts as "libel".
The definition will be less than ideal, open to abuse, and problematic, but having it is better than not, just as having a definition of "adult", "self defense", and "libel" are better than not having them.
The definition will be less than ideal, open to abuse, and problematic, but having it is better than not, just as having a definition of "adult", "self defense", and "libel" are better than not having them.