This is the kind of book that is either going to inspire or infuriate you, but it should provoke valuable discussion and thought in either case. Johnson's thesis is quite simple: the revolutionary thinkers whose ideas have shaped intellectual history over the past 250 years were, for the most part, lousy human beings. These were not not common or garden variety jerks but personalities whose flaws were so manifest that they must call into question the value of the theories they generated.
This is an interesting proposition. Does it matter that Peter Sellers, the world's greatest comedic actor, was a vile neurotic, that Marilyn Monroe was a goddess on screen but a drug-addled manipulator in everyday life, that Winston Churchill, who saved civilization during World War II, was also an alcoholic egomaniac? Probably not. But Johnson asks a deeper question: if a thinker cannot live out his own principles, can these ideas have any real merit? His book convinces us that there is a real connection between the rancid lives lived by intellectuals and the disasters their ideas produced.
For example, Jean-Jacques Rousseau is adored by educational theorists and his ideas are entrenched in the curricula of teachers' colleges, despite the fact that he serially abandoned every one of his children. Karl Marx was bourgeois to the core and seems to have exploited the only working-class woman he ever knew: paying her starvation wages, impregnating her and forcing her to abandon their child. Johnson lacerates the behaviour of these prominent figures but more importantly shows how their shabby personal values foreshadow the social harm their works engendered.