Well I don't actually need the Nas votes now sorry fellas. I'll make a new thread for him once we've established a working definition. Thanks to everyone for their contributions thus far.
I was positing the idea of 20-30 albums but I said elsewhere in the thread if I had to guess myself, based on my barometers,
there would be about 50-60 classics. I totally get what you mean with 36 Chambers and Cuban Linx or AMW and DC for example, but I would say all 4 are classics. But that's precisely why a definition has to be reached. Even if we all agree on a definition, our APPLICATION of said definition to various albums may still be different, but at least we're all working from the same starting point.
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At this point I want this thread, as
@mobbinfms advised, to be a place to discuss the definition of 'classic' and to reach an agreed definition so we can proceed to various artists in ensuing threads.