[regularfry]

I'm going to come back to this because I think it's an interesting point. Without "rules," how do you identify an example as belonging to a set? Rules for inclusion and/or exclusion must exist for the set to be defined. "I know it when I see it" is only really acceptable if you're a supreme court judge :-)

Specifically, we're talking not just about "music" here - which has an absurdly broad definition - but "metal," which falls under the category of western vocal-led performance. There are rules to this, and while breaking them might leave you with something that is ostensibly "music," it may well not leave you with "metal," "singing," a "song," or a "performance."