Quora Answer : How can you objectively quantify how good music is without being biased against newer music?
There are facts which can be objectively true but are also relational.
For example, it's objectively true that the moon is the satellite of the Earth. But it can't do that by itself. It needs the Earth's collaboration.
Without the Earth, the moon isn't a satellite of anything.
Similarly, it's an objective truth that London is the capital of the UK. But only because people in other parts of the country agree.
Being "good" in music (or any art) is the same kind of thing. It's an objective property which is nevertheless partly due to a relation with the audience.
How your music has affected listeners throughout history is one of the constituents of how good it is.
That isn't to say that goodness is a synonym for mere popularity. There's more to goodness than that. But if a piece of music doesn't impact musical history in some sense, when it gets the opportunity, then I don't think it can be said to be good.
How the audience responds, matters.
However, that audience response is over a longer period of time. It's not enough to be hugely popular in a short burst of modishness, because you have copied all the fashionable tropes of the time. Music also has to attract and hold attention after the moment of its creation has passed. When people are no longer caught up with a particular bunch of surface details.
For example, back in 1979 I suspect it was more or less impossible to separate which Disco records were great pieces of music vs. which were ephemeral fluff. Today, it's obvious that there's a bunch of records which have "stood the test of time". These are pieces that are loved, that get a party exited, that have musical flair and imagination and touch and uplift listeners from every generation.
We now know these records are "good".
But obviously, very new music has the problem that it hasn't been sufficiently tested for us to be sure. We have some good hunches now about disco records. But come back in 100 years for a really reliable opinion. Today's music, probably very few people except a few DJs who play a lot of records at clubs have much intuition about.