Liu Xinwu wrote in the 1980s in protest against Maoism, a political theory coined by Mao Zedong, founding father of China's communist regime. Mao Zedong, as a devoted nationalist who opposed both capitalism and imperialism, felt the only way to bring the weak and divided country of China together was through conformity through communism (Encyclopaedia Britannica, "Maoism: Ideology"). Author Xinwu uses his short story "Black Walls" to protest against the idea of conformity, to show the absurdity underlying the idea that the individual can truly conform to a greater society. Hence, we can say that the main conflict in "Black Walls" is self vs. society.
Xinwu's conflict of self vs. the conformity of society is portrayed through the character Zhou, who paints the walls of his tenement completely black. His neighbors criticize his actions, calling him insane. Zhou's choice to paint his walls black of course represents his own individuality, while the collective judgement of his neighbors represents society's conformity under Maoism. The influence of conformity under Maoism is best expressed in Mrs. Li's comment:
Maybe [her son] could make Zhou stop this silliness. Then they could repaint his wall white together. White was such a lovely colour. How could the walls of a house be anything but white?
The reference to being "together" of course represents the Maoist philosophy of society working in conformity together. Plus, the reference to the color white symbolizes brainwashing under Maoism. In terms of the artist's perspective, white is actually not a color; it's the absence of color ("Are Black & White Colors?"). Therefore, Mrs. Li's preference for the non-color white as such a "lovely colour" symbolizes how she has been brainwashed under Maoism to appreciate that which is actually valueless, to appreciate conformity rather than individuality.