“It is an iron law of history that what looks inevitable in hindsight was far from obvious at the time,” writes Yuval Noah Harari in his book Sapiens. History seems pretty clear when we look backwards. It is certainly complex, but whether it is our own lives, a sports season, or the rise and fall of an empire, we generally do a pretty good job of creating a compelling narrative to explain how history unfolded and why certain events took place. But these narratives create what we call the hindsight bias, where past events (in this case the course of human history) appear nearly deterministic. The reality is that small changes could shape the course of history in dramatic ways, and that the future is never clear at any point – as our current uncertainty about social media, climate change, and political polarization demonstrate. Harari continues, “in a few decades, people will look back and think that the answers to all of these questions were obvious,” but for us, the right answers are certainly far from obvious.
History, for human beings, is shaped by the innumerable decisions that we make every day. The course of history is not deterministic, but is instead chaotic. Harari argues that history is a level two chaotic system and writes, “chaotic systems come in two shapes. Level one chaos is chaos that does not react to predictions about it … level two chaos is chaos that reacts to predictions about it, and therefore can never be predicted accurately.”
The weather is a level one chaotic system because it doesn’t respond (on a day to day basis) to our predictions. Whether our computer models suggest a 1%, 45%, or 88% chance of rain on a given day doesn’t change what is going to happen in the atmosphere and whether it will or will not rain. Despite our sometimes magical thinking, scheduling a wedding or stating our hopes for or against certain weather patterns does not influence the actual weather.
History, is not a level one chaotic system. History is shaped by elections, the general beliefs within the public, the actions that people take, and how key actors understand risk and probability. Our predictions can greatly influence all of these areas. Predicting a landslide victory in an election can demotivate the losing side of a political divide, possibly turning what could have been a marginal victory into the predicted landslide as a sort of self-fulfilling prophecy. Reporting that general beliefs are becoming more or less prevalent among a population can influence the rate and direction of changing beliefs as people hear the predictions about belief trends (this seems like it may have happened as marijuana and gay marriage gained acceptance across the US). Our reactions to predictions can influence the final outcomes, contributing more uncertainty and chaos to the system.
We cannot predict exactly how people will react to predictions about the systems they participate in. It makes the predictions and forecasts more challenging since they have to incorporate different levels of response to various inputs. History cannot be thought of deterministically because so many small factors could have changed the outcomes, and those small changes in turn would have influenced exactly what predictions were made, in turn influencing the reactions of the people involved in the various actions of history. Our confidence in understanding history and why history played out as it did is not warranted, and is simply a fallacy.