Psychohistory is a fictional science in Isaac Asimov's Foundation universe which combines history, sociology, etc., and mathematical statistics to make general predictions about the future behavior of very large groups of people, such as the Galactic Empire. It was first introduced in the five short stories (1942–1944) which would later be collected as the 1951 novel Foundation.
Psychohistory depends on the idea that, while one cannot foresee the actions of a particular individual, the laws of statistics as applied to large groups of people could predict the general flow of future events. Asimov used the analogy of a gas: an observer has great difficulty in predicting the motion of a single molecule in a gas, but can predict the mass action of the gas to a high level of accuracy. (Physicists know this as the Kinetic theory.) Asimov applied this concept to the population of his fictional Galactic Empire, which numbered a quintillion. The character responsible for the science's creation, Hari Seldon, established two axioms:
- that the population whose behaviour was modeled should be sufficiently large
- that the population should remain in ignorance of the results of the application of psychohistorical analyses
There is a third underlying axiom of Psychohistory, which is trivial and thus not stated by Seldon in his Plan:
- that Human Beings are the only sentient intelligence in the Galaxy.
The Prime Radiant 
The Prime Radiant projects the equations onto walls in some unexplained manner, but it does not cast shadows, thus allowing workers easy interaction. Control operates through the power of the mind, allowing the user to zoom in to details of the equations, and to change them. One can make annotations, but by convention all amendments remain anonymous.
A student destined for speakerhood has to present an amendment to the plan. Five different boards then check the mathematics rigorously. Students have to defend their proposals against concerted and merciless attacks. After two years the change gets reviewed again. If after the second examination it still passes muster the contribution becomes part of the Seldon Plan.
The Radiant, as well as being interactive, employs a type of colour-coding to equations within itself for ready comprehension by Psychohistorians.
- Seldon Black are the original Seldon Plan equations developed by Seldon and Amaryl during the first four decades of Seldon's work at the University of Streeling, and define Seldon Crises, the Plan's duration, and the eventuation of the Second Galactic Empire.
- Speaker Red are additions to the plan by Speakers (Senior Mentalic Psychohistorians of the Second Foundation) since the time of Seldon.
- Deviation Blue are observed deviations away from Psychohistorical projections with a deviation in excess of 1.5 standard deviation of predicted outcomes (1.5 σ). The Era of Deviations, at the rise of the Mule, produced deviations in the Seldon Plan in excess of .5 through 10 sigmas, and the resolution of this period required a full century of labour on the part of the Second Foundation to return the Galaxy to the Plan.
Other colours have been imagined by fans, and mentioned by Asimov, such as:
- Notation Green - additions of pertinent scientific papers appended to findings (Forward the Foundation)
- Projection Purple - Useful for determining limits on future Speaker Red equations, using projections of events with regard to a very sketchy but still monumental Seldon Black scheme. A tool of the first three generations of Psychohistorians after Seldon, and by the 5th Century of the Plan a teaching tool at most. (Forward the Foundation)
In his later career, Asimov described some historical (pre-Seldon) origins of psychohistory. In The Robots of Dawn (1983), which takes place thousands of years before Foundation (1951), he describes roboticist Han Fastolfe's attempts to create the science based on careful observation of others, particularly of his daughter Vasilia. Prelude to Foundation (1988) suggests that one of Fastolfe's robots, R. Daneel Olivaw, manipulated Seldon into practical application of this science.
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The fact that Seldon established a Second Foundation of mental-science adepts to oversee his Seldon Plan might suggest that even Seldon himself had doubts about the ultimate ability of a purely mathematical approach to predicting historical processes, and that he recognized that the development of psychic skills, such as those used by the Mule, had the ability to invalidate the assumptions underlying his models, though he did not (and could not) predict the appearance of the Mule himself. The Seldon methodology might therefore only work at a certain level of species-development, and would over time become less useful.
Psychohistory has one basic, underlying limitation which Asimov postulated for the first time on literally the last page of the final book in the Foundation series: psychohistory only functions in a galaxy populated only by humans. In Asimov's Foundation series, humans form the only sentient race that developed in the entire Milky Way Galaxy. Seldon developed psychohistory to predict the actions of large groups of humans. Even robots technically fall under the umbrella of psychohistory, because humans built them, and they thus represent more or less a human "action", or at least, possess a thought-framework similar enough to that of their human creators that psychohistory can predict their actions. However, psychohistory cannot predict the actions of a sentient alien race; their psychology may differ so much from that of humans that normal psychohistory cannot understand or predict their actions.
The end of the series offered two possibilities:
- sentient races actually very rarely develop, such that only humans evolved in the Milky Way Galaxy, and in most other galaxies, it appears probable (given this assumption) that only one sentient race would develop. However, statistically two or more alien races might evolve in the same galaxy, leading them into inevitable conflict. The fighting in this other galaxy would only end when one race emerged the victor, and after the prolonged conflict with other races, would have developed an aggressive and expansionist mindset. In contrast, humans had never encountered another sentient species in the Milky Way Galaxy, so they never felt greatly compelled to expand to other galaxies, but instead to fight other humans over control of the Milky Way. Eventually, such an aggressive alien race would expand from galaxy to galaxy, and eventually try to invade the Milky Way Galaxy.
- through genetic engineering, subsets of humanity could alter themselves so significantly from baseline humans that they could for all intents and purposes be considered "aliens". Specifically exemplifying this theory we find Asimov's Solarians: humans evolved from an old Spacer world who had genetically modified themselves into hermaphrodites with telekinetic mental powers.
Asimov on psychohistory 
- Gross: "What did you have in mind when you coined the term and the concept?"
- Asimov: "Well, I wanted to write a short story about the fall of the Galactic Empire. I had just finished reading the Decline and Fall of the Roman Empire [for] the second time, and I thought I might as well adapt it on a much larger scale to the Galactic Empire and get a story out of it. And my editor John Campbell was much taken with the idea, and said he didn't want it wasted on a short story. He wanted an open-ended series so it lasts forever, perhaps. And so I started doing that. In order to keep the story going from story to story, I was essentially writing future history, and I had to make it sufficiently different from modern history to give it that science fictional touch. And so I assumed that the time would come when there would be a science in which things could be predicted on a probabilistic or statistical basis."
- Gross: "Do you think that would be good if there really was such a science?"
- Asimov: "Well, I can't help but think it would be good, except that in my stories, I always have opposing views. In other words, people argue all possible... all possible... ways of looking at psychohistory and deciding whether it is good or bad. So you can't really tell. I happen to feel sort of on the optimistic side. I think if we can somehow get across some of the problems that face us now, humanity has a glorious future, and that if we could use the tenets of psychohistory to guide ourselves we might avoid a great many troubles. But on the other hand, it might create troubles. It's impossible to tell in advance."
Asimovian psychohistory and similar concepts in other fiction 
- Asimov's ideas figure prominently in Donald Kingsbury's novel Psychohistorical Crisis, a re-imagining of the world of Isaac Asimov's Foundation trilogy, set after the establishment of the Second Empire.
- In Fantastic Four #542, Mister Fantastic, involved in the Marvel Universe's Civil War event, reveals his real reason for supporting the superhero registration act which prompted the Civil War — his development of a working version of Isaac Asimov's fictional psychohistory-concept. Mister Fantastic's application of this science indicates to him that billions will die in escalating conflicts unless the act becomes law.
- In Ghost Rider 2099 #1, a group of AIs predict that human society (and therefore the global network the AIs exist in) will crash in 2113. One of them mentions that Asimov conceived the idea of such a mathematical model.
- The concept of psychohistory also appears in the Legend of the Galactic Heroes (銀河英雄伝説, Ginga Eiyū Densetsu) by Yoshiki Tanaka.
- The Technocore, the AI civilisation in Dan Simmons's novel Hyperion, is capable of statistically predicting future events to a very high degree of accuracy.
- The novel House of Suns by Alastair Reynolds features a device called the "Universal Actuary", which aims to predict the future of civilisations in a manner very similar to psychohistory. As the limits of slower than light travel prevent any interstellar civilisations from lasting very long, one of its most important uses is to determine how much longer a given civilisation will last.
- In The Country of the Blind, Michael F. Flynn creates competing groups of psychohistorians.
- In the 'Shattered Glass' universe of 'Transformers: Timelines', Megatron uses math to predict the future in what is likely a reference to Asimov.
- In the episode Statistical Probabilities of Star Trek: Deep Space Nine where a think tank uses maths to predict the future in a manner likely to be a reference to Asimov.
- In the novel Preserver (Star Trek) by William Shatner the science of psychohistory is used, and mentioned by name, by scholars at outpost Memory Alpha. Memory Alpha was shown in the Star Trek: Original Series episode The Lights of Zetar, although psychohistory was never mentioned in the episode.
Beyond fiction 
Polymath Adolphe Quetelet developed in the 19th century what he called "social physics". Quetelet studied the statistical laws underlying the behaviour of what he called "average man".
Some individuals and groups, inspired by Asimov's psychohistory, seriously explore the possibility of a working psychohistory not unlike the one imagined by Asimov — a statistical study of history that could help in the formulation of some "theory of history" and perhaps become a tool of historical prediction.
Complexity theory, an offshoot of chaos mathematics theory, explored by Stuart Kauffman in his books "At Home in the Universe" and "Redefining the Sacred" cover the concept of statistical modeling of sociological evolutions. The concept was also explored in "Order Out of Chaos" by Ilya Prigogine.
Another theory that has similarities to Psychohistory is "Generational Dynamics" proposed by John J. Xenakis, where he proposes, "Generational Dynamics is a historical methodology that analyzes historical events through the flow of generations, and uses the analysis to forecast future events by comparing today's generational attitudes to those of the past". Essentially, generations immediately after a major crisis event (stock market crash, civil war, world war) will be unwilling to live through such events again and will be risk-averse. Generations after them may well be aware of previous crisis events, but will be more risk-tolerant, as they have not been exposed to the crisis themselves. Xenakis states that this allows one to predict future crisis events by analyzing the current generation's outlooks.
Nathan Eagle and Alex Pentland (among others) have developed useful techniques for predicting human behavior through statistical analysis of smartphone data.
At the 67th science-fiction world convention in Montreal, Paul Krugman, the Nobel laureate in Economics, mentioned Hari Seldon, a central character in Foundation who was a psychohistorian, as his inspiration to study Economics since it's the closest thing to Psychohistory, according to P. Krugman.
In role-playing games 
Psychohistory appears in the Traveller science-fiction role-playing game, released in 1977. The alien race known as the Hivers use extensive manipulation of other cultures based on psychohistorical data to achieve their own ends. Rumors ascribe the assassination of the Third Imperium's Emperor Strephon to a Hiver manipulation based on psychohistorical data indicating the eventual fall of the Third Imperium. Humans in the setting have also attempted to use psychohistory, but with less skill or success; the Psionic Suppressions (which turned public opinion within the human Imperium against those with paranormal mental abilities, forcing them to go into hiding) resulted, unknown to most, from an experiment in psychohistory that got out of control and went much farther than the experimenters intended.
Literary influences 
Some literary critics have described Asimov's psychohistory as a reformulation, either for better or worse, of Karl Marx's theory of history (historical materialism), though Asimov denied any direct influence. Arguably, Asimov's psychohistory departs significantly from Marx's general theory of history based on modes of production (as distinct from Marx's model of the capitalist economy, where "natural laws" work themselves out with "iron necessity") in that psychohistory is predictive (if only in the sense of involving precisely stated probabilities), and in that psychohistory is extrapolated from individual psychology and even from physics. Psychohistory also has echoes of modernization theory and of work in the social sciences that by the 1960s would lead to attempts at large-scale social prediction and control such as Project Camelot.
See also 
- Psychohistory, the real (non-fictional) study of the psychological motivation of groups in historical and current events
- Macroeconomics, the real economics sub-field that considers aggregate behavior
- Economic history, the real economics sub-field trying to discover long-run trends in human behaviour (the equations of the Prime Radiant)
- Praxeology, the study of human action
- Robopsychology, the fictional study of the personalities of intelligent machines
- Quantitative psychology, the real psychology sub-field that applies statistical mathematics to psychology
- Mathematical sociology, the real sociology sub-field that applies statistical mathematics and other quantitative approaches such as social network analysis to micro- and macro-social phenomena
- Social thermodynamics theory, which attempts to describe social phenomena using an approach with the mathematical structure of thermodynamics.
- Cliodynamics, the real area of research focused on mathematical modeling of historical dynamics
- Societics, the fictional study of "the interaction of individuals in a culture, the interaction of the group generated by these individuals, the equations derived therefrom, and the application of these equations to control one or more factors of this same culture"
- Survival analysis, a branch of statistics which deals with death in biological organisms and failure in mechanical systems. This topic is called reliability theory or reliability analysis in engineering, and duration analysis or duration modeling in economics or event history analysis in sociology.
Notes and references 
- "Sound Recordings", retrieved 2008-05-07
- "psychohistory : The psychohistory project". Retrieved 2011-02-05.
- "Eigenbehaviors: Identifying Structure in Routine" (PDF). Retrieved 2011-05-01.
- Booker, M. Keith. "Monsters, Mushroom Clouds, and the Cold War: American Science Fiction and the Roots of Postmodernism, 1946-1964". Westport, Connecticut: Greenwood Press, 2001. pp. 34-38. "Numerous critics have noticed the parallels between Marx's and Seldon's visions of history." Critics whom Booker discusses regarding the connection between Marxism and psychohistory include James Gunn, Donald Wollheim, and Charles Elkins.
- Angus Taylor. "Asimov, Popper, and the Fate of the Galaxy", Foundation: The Review of Science Fiction 42 (1988): 59-64.
- Harrison, Harry (2009). Toy Shop and Two Others. Wildside Press LLC. p. 27. ISBN 978-1-4344-5896-4. Retrieved 2011-10-14. "The applied study of the interaction of individuals in a culture, the interaction of the group generated by these individuals, the equations derived therefrom, and the application of these equations to control one or more factors of this same culture"
- Host: Terry Gross (September 25, 1987). "Interview with Issac Asimov" (MP3). Fresh Air. 12 minutes in. Archived from the original on June 3, 2011. http://web.archive.org/web/20110603231018/http://homepage.mac.com/pockyrevolution/asimov/Asimov_interview.mp3.