We humans know more truths than any species on earth. Yet we also believe the most falsehoods.
By Yuval Noah Harari 
Many people believe that truth conveys power. If some leaders, religions or ideologies misrepresent reality, they will eventually lose to more clearsighted rivals. Hence sticking with the truth is the best strategy for gaining power. Unfortunately, this is just a comforting myth. In fact, truth and power have a far more complicated relationship, because in human society, power means two very different things.
On the one hand, power means having the ability to manipulate objective realities: to hunt animals, to construct bridges, to cure diseases, to build atom bombs. This kind of power is closely tied to truth. If you believe a false physical theory, you won’t be able to build an atom bomb.
On the other hand, power also means having the ability to manipulate human beliefs, thereby getting lots of people to cooperate effectively. Building atom bombs requires not just a good understanding of physics, but also the coordinated labor of millions of humans. Planet Earth was conquered by Homo sapiens rather than by chimpanzees or elephants, because we are the only mammals that can cooperate in very large numbers. And large-scale cooperation depends on believing common stories. But these stories need not be true. You can unite millions of people by making them believe in completely fictional stories about God, about race or about economics.
The dual nature of power and truth results in the curious fact that we humans know many more truths than any other animal, but we also believe in much more nonsense. We are both the smartest and the most gullible inhabitants of planet Earth. Rabbits don’t know that E=MC² , that the universe is about 13.8 billion years old and that DNA is made of cytosine, guanine, adenine and thymine. On the other hand, rabbits don’t believe in the mythological fantasies and ideological absurdities that have mesmerized countless humans for thousands of years. No rabbit would have been willing to crash an airplane into the World Trade Center in the hope of being rewarded with 72 virgin rabbits in the afterlife.
When it comes to uniting people around a common story, fiction actually enjoys three inherent advantages over the truth. First, whereas the truth is universal, fictions tend to be local. Consequently if we want to distinguish our tribe from foreigners, a fictional story will serve as a far better identity marker than a true story. Suppose we teach our tribal members to believe that “the sun rises in the east and sets in the west.” That makes for a very poor tribal myth. For if I encounter somebody in the jungle and that person tells me that the sun rises in the east, it might indicate that she is a loyal member of our tribe, but it might just as well indicate that she is an intelligent foreigner who reached the same conclusion independently of our tribe. It is therefore better to teach tribe members that “the sun is the eye of a giant frog that each day leaps across the sky,” since few foreigners — however intelligent — are likely to hit upon this particular idea independently.
The second huge advantage of fiction over truth has to do with the handicap principle, which says that reliable signals must be costly to the signaler. Otherwise, they can easily be faked by cheaters. For example, male peacocks signal their fitness to female peahens by sporting an enormous colorful tail. This is a reliable signal of fitness, because the tail is heavy, cumbersome and attracts predators. Only a truly fit peacock can survive despite this handicap. Something similar happens with stories.
If political loyalty is signaled by believing a true story, anyone can fake it. But believing ridiculous and outlandish stories exacts greater cost, and is therefore a better signal of loyalty. If you believe your leader only when he or she tells the truth, what does that prove? In contrast, if you believe your leader even when he or she builds castles in the air, that’s loyalty! Shrewd leaders might sometimes deliberately say nonsensical things as a way to distinguish reliable devotees from fair-weather supporters.
Third, and most important, the truth is often painful and disturbing. Hence if you stick to unalloyed reality, few people will follow you. An American presidential candidate who tells the American public the truth, the whole truth and nothing but the truth about American history has a 100 percent guarantee of losing the elections. The same goes for candidates in all other countries. How many Israelis, Italians or Indians can stomach the unblemished truth about their nations? An uncompromising adherence to the truth is an admirable spiritual practice, but it is not a winning political strategy.
Some might argue that the long-term costs of believing fictional stories outweigh any short-term advantages in social cohesion. Once people get in the habit of believing absurd fictions and convenient falsehoods, this habit would spill into more and more areas, and they would consequently make bad economic decisions, adopt counterproductive military strategies and fail to develop effective technologies. While this occasionally happens, it is far from being a universal rule. Even the most extreme zealots and fanatics can often compartmentalize their irrationality so that they believe nonsense in some fields, while being eminently rational in others.
Think, for example, about the Nazis. Nazi racial theory was a bogus pseudoscience. Though they tried to buttress it with scientific evidence, the Nazis nevertheless had to silence their rational faculties in order to develop a belief strong enough to justify murdering millions of people. Yet when it came time to design gas chambers and prepare timetables for the Auschwitz trains, Nazi rationality emerged from its hiding place intact.
What’s true of the Nazis is true of many other fanatical groups in history. It is sobering to realize that the Scientific Revolution began in the most fanatical culture in the world. Europe in the days of Columbus, Copernicus and Newton had one of the highest concentrations of religious extremists in history, and the lowest level of tolerance.
Newton himself apparently spent more time looking for secret messages in the Bible than deciphering the laws of physics. The luminaries of the Scientific Revolution lived in a society that expelled Jews and Muslims, burned heretics wholesale, saw a witch in every cat-loving elderly lady and started a new religious war every full moon.
If you had traveled to Cairo or Istanbul around 400 years ago, you would have found a multicultural and tolerant metropolis where Sunnis, Shiites, Orthodox Christians, Catholics, Armenians, Copts, Jews and even the occasional Hindu lived side by side in relative harmony. Though they had their share of disagreements and riots — and though the Ottoman Empire routinely discriminated against people on religious grounds — it was a liberal paradise compared with Western Europe. If you had then sailed on to contemporary Paris or London, you would have found cities awash with religious bigotry, in which only those belonging to the dominant sect could live. In London they killed Catholics; in Paris they killed Protestants; the Jews had long been driven out; and nobody even entertained the thought of letting any Muslims in. And yet the Scientific Revolution began in London and Paris rather than in Cairo or Istanbul.
The ability to compartmentalize rationality probably has a lot to do with the structure of our brain. Different parts of the brain are responsible for different modes of thinking. Humans can subconsciously deactivate and reactivate those parts of the brain that are crucial for skeptical thinking. Thus Adolf Eichmann could have shut down his prefrontal cortex while listening to Hitler give an impassioned speech, and then reboot it while poring over the Auschwitz train schedule.
Even if we need to pay some price for deactivating our rational faculties, the advantages of increased social cohesion are often so big that fictional stories routinely triumph over the truth in human history. Scholars have known this for thousands of years, which is why scholars often had to decide whether they served the truth or social harmony. Should they aim to unite people by making sure everyone believes in the same fiction, or should they let people know the truth even at the price of disunity? Socrates chose the truth and was executed. The most powerful scholarly establishments in history — whether of Christian priests, Confucian mandarins or Communist ideologues — placed unity above truth. That’s why they were so powerful.