The infamous manifesto Adolf Hitler wrote while in prison after a failed coup in 1923, Mein Kampf or My Struggle, in which the dictator outlined his idea of a global Jewish conspiracy, is a surprise hit on the ebook market. While the book’s print copy sales remain stagnant, the ebook is in the top 20 on iTunes’s Politics & Events chart, next to books by Sarah Palin and Glenn Beck, the number one Propaganda & Political Psychology book on Amazon, and the 17th bestseller in the company’s Nationalism list. How could that be?

Chris Faraone explains why in a fascinating essay that argues ebooks provide the perfect format for reading controversial material. “Mein Kampf could be following a similar trend to that of smut and romance novels,” Faraone writes. Customers may have not wanted to be seen reading the book or having it on their shelf at home, but the cheap digital copies “can be quietly perused then dropped into a folder or deleted.”...