These opposites--literally polar opposites in the case of the latter--are fodder for novelists. Writers frequently explore the areas between those opposites. Maybe we should call them, in the case of black and white, especially, “gray” areas.
Melville, famously, turned convention on its head in Moby Dick by making white an evil. I, less famously, did something of the the same thing in my Wizards Trilogy. At first, it was clear that the evil wizard was black. My editor at the time was very uncomfortable with that because she thought I was reinforcing racial stereotypes. Even when I pointed out that later in the book we would learn that the wizard was not a black man, but one who painted himself black, the topic made her queasy. Even later, we learn that the white wizard is not so good after all, and that she also paints herself white, I don’t think my editor was completely appeased. Both were actually pink, and neither the black nor white wizard was all good or bad. Still, the way we think about those two terms is so culturally hard wired that it was difficult for her to get around it. It was probably difficult for some readers, too, which was the point I was trying to make.
I’m currently reading Drunk Tank Pink, by Adam Altar. Among other things, it explores our cultural, biological and psychological reactions to things that would not logically make a difference. The pink color of the title physically weakens people exposed to it. People named Ken are more likely to support relief efforts for hurricanes named Katrina because their names share that initial letter. Job applicants named Bob are more likely to be selected than applicants name Trayvon, even when their resumes are identical.
And which way is up? North, of course. We even expect rivers to flow from north to south, rather than the other way around. This is reinforced in the United States by that big sucking drain, the Mississippi.
In my current draft, up and down make only the slightest difference to anjels, until one of them discovers the ability to fall. It is at times like that, when our world views are challenged, that things really get interesting.