What the heck does that mean? “Understanding music”? I’m not a big fan of the phrase. Music is only music. Anything to “understand” about it is not musical. If I want to better understand an opera by Mozart, I learn about its creator, what he was doing at the time, what the rest of his country was doing, what the musical tastes and conventions were at the time, and probably some music theory (which is redundant because “music theory” is really just another way of saying “musical tastes and conventions of the time”). Though all these things affected the creation of the music, they are not the music. So basically, “understanding music” tends to mean “being aware of a piece’s origins”.
Understanding music can change a person’s opinion of a piece. For example, a person may hate Tim Burton’s Corpse Bride. Later on, that person may learn about all the labor that went into its stop-motion animation and may change his opinion, saying something like “it amazes me the dedication those animators had!” … but then his opinion is no longer based on the end product itself, but on its origins.
Do you have to know a musical piece’s origins before deciding whether or not you like it? If you heard a short waltz for piano and you were told it was written by Beethoven, would you like more than if it had been written by a six year old? Or some poor guy with some “rags-to-riches” story? Would you like it more if it had taken twenty years to write? What if it was written in less than an hour?
Unfortunately in the real world I think these outside factors do indeed influence opinions. Perhaps it’s because people don’t like to just be affected by music, they want to know the reason they’re being affected. Alas, it’s currently impossible to understand the way our chemical brains work, so many people just try to find reasons elsewhere and seek the fool’s gold of “understanding music”.
I’m not saying “understanding music” is bad; it can be extremely interesting and helpful, especially if you’re a composer. But one should be cautious that his opinions of a piece of music are not dictated by his opinions of its origins.
Likewise, one should be cautious not to say something like “you don’t like this music because you don’t understand it.” Those are the words of snobs who do let the origins of a piece dictate their opinions.
And this does not apply to all the arts, such as literature, for arts such as literature have much more objective concrete meanings. Music has no objective concrete meaning.