scarius from shafted says this in his most recent post:

However, I suspect that with enough thought I could come up with a definition of what makes a Lego-Block a Lego-Block and not a Lego-Gear or even a Lego-Beam. It’d take a while, but I think it could be done. It’d probably involve having lots of rules regarding various facets of the piece including function, shape, and connections. Similarly, most definitions are probably composites, for example you could define Love as some combination of chemical imbalances, behaviors, and mental processes. You’d probably also need some model representing the interplay of strictness and relevance of different facets as pertaining to the classification of a particular object. However, given enough time to think upon the matter, you could probably in this fashion define Love as opposed to Lust or Like just as you could define Lego-Block as opposed to Lego-Beam or Lego-Gear.