It has become fashionable to look at Hitler and Stalin as the twin monsters of 20th-century history. Entire volumes (like Alan Bullock's "Hitler and Stalin: Parallel Lives" and Richard Overy's "The Dictators: Hitler's Germany, Stalin's Russia") have examined these two tyrants through the lens of the compare-and-contrast school of history writing, and much ink has been spilled debating which of them was worse - never mind that such debates seem beside the point, indeed offensive, given the fact that both men were responsible for the deaths of millions upon millions of people.

In their new book, "Mao: The Unknown Story," Jung Chang and Jon Halliday make an impassioned case for Mao as the most monstrous tyrant ever. They argue that he was responsible for "well over 70 million deaths in peacetime, more than any other 20th-century leader," and they argue that "he was more extreme than Hitler or Stalin" in that he envisioned a brain-dead, "completely arid society, devoid of civilization, deprived of representation of human feelings, inhabited by a herd with no sensibility, which would automatically obey his orders."