Psychohistory

In Isaac Asimov's Foundation series, Hari Seldon, a mathematician, predicts that the mighty Galactic Empire, which ruled the galaxy for thousands of years, is on the verge of collapse and that the ensuing chaos will lead to a dark age lasting 30,000 years. However, Seldon also finds that "a carefully designed nudge can change that path". Therefore, Seldon plans to create a "Foundation" that will preserve human knowledge and culture through the dark age and eventually pave the way for a new era of enlightenment. The core concept of such Seldon Plan is Psychohistory: a mathematical and scientific approach to predicting the behavior of large populations of people over time. Before Hari Seldon, a group of mathematicians and scientists developed the psychohistory concept but failed due to individual human beings' unpredictable and chaotic nature. Hari Seldon developed a new approach to psychohistory: we can eradicate the chaoticity with certain preconditions:

1. Large populations. Psychohistory assumes that it can only make accurate predictions about large populations of people. The larger the population, the more accurate the forecast.
2. Limited information. Psychohistory assumes that the information available about individuals within the population cannot be predicted accurately. Due to this, only a few knowledgeable individuals know about the existence of Psychohistory. Furthermore, people think Psychohistory is an antiquated and obsolete field of study, just like how we feel about Alchemy.
3. Homogeneity. Psychohistory assumes that people are relatively homogeneous, with similar values, beliefs, and behaviors, far from unexpectedness. Later Foundation series describes that the Mule, a mutant who can manipulate emotions, invalidated the Seldon Plan.
4. Only humans can affect the course of history. Psychohistory assumes that only humans can affect the course of history. It does not consider the possibility of external factors, such as natural disasters or extraterrestrial beings, that could disrupt or alter the predicted course of events.
5. The speed of scientific progress should not outpace historical progress. Psychohistory assumes that technological progress could cause a "Singularity" that would disrupt the predicted course of events and lead to unintended consequences.

Not only this, but Seldon also recognized that Psychohistory observing the future also affects history in the long term (Just like Copenhagen Interpretation in Quantum Physics) and would become increasingly less reliable as the time horizon extended further into the future. So he devised a plan to create two complementary Foundations that would be separated by a significant distance, ensuring that they could operate independently and that unforeseen events would not influence them. This is known as the Second Foundation in the series.