If liberty means anything at all, it means the right to tell people what they don't want to hear." - George Orwell
The author, Kirsten Powers, although a liberal, strongly condemns what we called for a while political correctness and what she considers censorship and calls Silencing.
Her thesis is that it's easier for people "to demonize their opponents and sanctify themselves as higher moral beings than treat differences of opinion respectfully." This applies to the right as well as the left, but it's the left she's going after in this book. If people are punished for saying something that offends someone else (and they are) and if "offended" is undefined except by the person who takes offense, that is a critical loss of free speech.
Powers doesn't quote it but the point she makes is that power corrupts and when you give college students the power to have a septuagenarian professor suspended because of "micro-aggression," you need not be surprised if things escalate and they attempt to destroy others for less and less significant "offenses."
A good book, a little unorganized, filled with examples we have seen in the news in recent years.