Amazon has adopted a rule against books that contain anything the company labels as “hate speech.” It appears there was no announcement of the new rule. It was only noticed by media after the online retailer recently banned a book that criticizes transgender ideology. It’s not clear what Amazon means by “hate speech” or even if it used that label to drop that particular book. In general parlance, Americans hold widely diverging views on what constitutes hate speech, a 2017 Cato poll found. Some tech platforms describe it as speech that disparages people based on characteristics such as race, gender, and sexual proclivities. But insider evidence indicates the companies aren’t clear on where to draw the lines, perpetually redraw them, and at least in some instances ignore violations when politically convenient. “As a bookseller, we provide our customers with access to a variety of viewpoints, including books that some customers …