The back-story of Psychohistorical Crisis seems oddly familiar. Long ago the unnamed Founder used "psychohistory" mathematics to predict the Galactic Empire's collapse into a 30,000-year interregnum of anarchy. Working from the central Imperial world Splendid Wisdom, he tried to save the future by establishing a colony of technocrats on remote Faraway: the Overt Arm of the Plan, nucleus for a greater Second Empire. When events were derailed by an unpredictable hazard – the warlord Cloun-the-Stubborn, armed with techniques of emotional control – the Covert Arm took action....
Yes, Kingsbury's novel is a sequel to Isaac Asimov's original "Foundation" trilogy, but unauthorized by the Asimov estate. Hence the above subtle transformations of Hari Seldon, Trantor, Terminus, the Foundation, the Mule (that "clownish" conqueror) and the Second Foundation.
Being unauthorized provides freedom to discard all the dreadful tat which Asimov later added to his rough-hewn, jerkily told but memorable trilogy. Crisis has no links to the robot series, beyond the joke appearance of a nonsentient robot called Danny-Boy whose many undocumented skills include "detective". Thus, no millennial conspiracies of telepathic robots overseeing events. Just as Asimov first imagined it, psychohistory had to be invented and operated without external tinkering. Good.
Kingsbury goes further, and rationalizes all those mutant mental powers. With the unfair advantage of half a century's hindsight, his solution is ingeniously Asimovian. One established Galactic Empire prop, the dread psychic probe, is already a wireless mind-machine interface ... needing only slight extrapolation to account for Cloun/Mule-style emotional control.
Many centuries later, this technology leads to the mindlinked computer familiar or "fam" used to expand human intelligence and memory throughout the Second Empire – which is ruled as expected by fanatically secretive masters of prediction, here called the Pscholars. Psychohistorical Crisis begins with unfortunate Eron Osa being punished for unstated high crimes by the destruction of his fam and thus much of his memory and mind. We flash back twenty years ...
What follows is both a story – wide-ranging, full of engaging characters – and a gradually assembled argument against the stated principles of psychohistory. For one thing, doesn't control of the future by a self-perpetuating elite tend towards the deadening stasis of safe choices which Asimov himself considered and rejected in The End of Eternity?
Real-world systems contain instabilities. Despite the Pscholars' absolute rule, there are still enclaves of rebel mathematicians hoping to compute alternative futures. Would-be conspirators are allured by the notion of a short life and a merry one. Promising young Eron is manipulated in hope that one day he'll become a sleeper among the Pscholars. Nothing works quite as intended, but Eron's erratic education, including a wonderfully silly visit to the planet-wide heritage industry of Earth, steers him towards the Kingsbury argument that psychohistory's ultimate defence is also its worst flaw.
Meanwhile we tangle with history, archaeology, the theory of weights and measures, galactic astrology – adapted as the conspirators' stalking-horse – and, in lectures by the Founder himself, information theory. Psychohistorical Crisis wears its erudition lightly, though, and entertains throughout. Arguably it's the best Foundation (sorry, Overt Arm) novel likely to be written this side of Star's End.