Niall Ferguson has written an old man’s book.

Not too many years ago, in “Colossus” (2004), Ferguson was advocating that the U.S. face up to its Imperial destiny. And in “Civilization: The West and the Rest” (2011) he described how “six killer apps” made the West great.

No more Churchill’s sunny uplands for us, apparently, as “The Great Degeneration: How Institutions Decay and Economies Die,” makes clear. Ferguson writes, “My over-arching question is: What exactly has gone wrong in the Western world in our time?”

Surely, “everything’s going to hell” is the old man’s lament. Ferguson, who once personified the Oxford history don as sex symbol, turned 49 this year, so “Degeneration” feels a bit rushed, premature. On the other hand, looking at the last five years would depress anyone.