This article is an excerpt from the Shortform summary of "Sapiens: A Brief History of Humankind" by Yuval Noah Harari. Shortform has the world's best summaries of books you should be reading.
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What is hindsight bias? How does it influence how we think about not only the past, but also the present and the future?
Hindsight bias is the human tendency to believe that events that have already happened were more predictable than they actually were. Looking back, we think we could have predicted how history would unfold—it seems obvious in hindsight. But while today we can describe how history has unfolded so far, we can’t say why it’s turned out the way it has.
We’ll go in depth into the hindsight bias definition above and cover hindsight bias examples.
Hindsight Bias Example #1
History Isn’t Predictable (or Explainable)
For example, we can detail the events leading up to Christianity’s take-over of the Roman Empire, but we can’t determine the causal links between these events. We don’t know why Emperor Constantine chose to convert to Christianity when he could have continued to practice his own polytheistic religion. He also could have converted to Manichaeism, Zoroastrianism, Judaism, or Buddhism, all of which were available to him at the time. But he chose Christianity, which was actually an unlikely choice. This is a hindsight bias example (also known as the hindsight fallacy).
The less we know about a historical period, the more we tend to think that the events of that period were inevitable and the more we’re vulnerable to hindsight bias. The more we learn, the more we see all the roads untaken, some of which were more probable. History often takes unexpected turns—what seems inevitable now was seen as extremely unlikely at the time.
Hindsight Bias Example #2
For instance, if you were to suggest in AD 306 that Christianity, an obscure sect of Judaism, would become the religion of the Roman Empire, your contemporaries would laugh at you. Similarly, no one could have reasonably predicted that a tiny Russian faction called the Bolsheviks would take over their country in a matter of years. It’s not that anything is possible in history. It’s just that there are far more options than we realize. This is a hindsight bias example.
According to the hindsight bias definition, for the same reasons we can’t explain why history happened the way it did, we can’t predict the future. We can’t know if we’re out of the global economic crisis or if China will become the world’s leading superpower.
Why do we fall for the hindsight fallacy (hindsight bias)? We like to think that history is deterministic because it means that everything that has happened was supposed to happen. It’s comforting. Conversely, it’s unnerving to realize that all the events leading up to this moment could have easily turned out differently and that it’s only a coincidence that most of us today believe in collective fictions such as capitalism and human rights.
History Is a Level Two Chaotic System
One reason we’re vulnerable to the hindsight bias is that history is chaotic—it’s too complex to understand how all the variables interact. Not only is history chaotic, it’s a “level two” chaotic system.
A level one chaotic system is not affected by predictions we make about it. For example, the weather is a level one chaotic system. We can make predictions about the weather tomorrow, but those predictions don’t have the ability to change the weather tomorrow.
A level two chaotic system is affected by predictions we make about it. For example, the oil market is a level two chaotic system. If we predict that the price of oil will increase from $90 a barrel today to $100 a barrel tomorrow, traders will buy a bunch of oil today so they can benefit from the rise in price tomorrow. But this action increases oil prices today, which in turn changes the price of oil tomorrow.
Similarly, politics is a level two chaotic system. If someone were to have predicted the Arab Spring and told Egypt’s President Mubarak that a revolution was imminent, he would have taken actions to prevent it, perhaps lowering taxes and increasing government handouts. In doing so, he likely would have prevented the Arab Spring, nullifying the original prediction.
Level two chaotic systems, like history, are inherently unpredictable. These are hindsight bias examples.
Why We Study History
If there are so many unknowns, we all have a hindsight bias, and we can’t use our knowledge of history to predict the future, what’s the point of studying it?
Despite the hindsight bias, we study history to better understand what’s happening today. It’s important to realize that nothing in our lives or the world is inevitable. Just as the past had many variables, the present is full of possibilities, and we should never assume that a single path is natural or unavoidable.
For example, studying how Europeans came to have power over Africans reminds us that this power dynamic has nothing to do with racial inferiority and superiority. History could have easily turned out differently, perhaps with Africans enslaving Europeans. We study history, in part, to remind ourselves that our discriminatory hierarchies are based on random events and the fictions that spring from them. They aren’t natural and they weren’t inevitable.
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Here's what you'll find in our full Sapiens summary:
- How Sapiens outlived and outlasted the 8+ other human-like species on Earth
- The 3 critical revolutions in human existence that led to our domination of the planet
- How much of what powers our world today is really just a shared mass delusion
- What the future of humanity might look like
