Political Correctness reveals its core of nihilism when expressing its lack of understanding of evil.
A staple of PC discourse is to depict some atrocity then to conclude with "I just don't understand it".
As Tolkien so memorably depicted in Lord of the Rings, it is characteristic of evil not to understand, in particular evil cannot understand good.
Good comprehends all, including evil (at a metaphysical level this is because Good is primary and evil a negation).
But PC cannot comprehend evil. Because PC is derived from, based-upon, an expression-of nihilism - that is upon the denial of reality, or the relativity of reality (same thing) - PC is so radically incomplete, truncated, self-refuting a moral system that it has lost the ability to understand evil.
For PC evil is merely random, an inexpicable atrocity - a disequilibrium; but soon explained-away soon forgotten, soon re-framed.
But never understood.