To those of us who live in modern democratic societies, it can seem obvious that democracy is the right form of government. Democracy respects the equality of citizens and our freedom to govern ourselves.
But the superiority of democracy is not obvious to everyone. Even today, many societies are not democratic and these governments survive not merely by force of arms, but also because some people believe that democracy is not the best form of government.
In ancient Athens, democracy was a fleeting and tentative experiment with many detractors. By many accounts, Plato was no fan of democracy. Plato compared democracy to a ship of fools.
Imagine then a … ship in which there is a captain who is taller and stronger than any of the crew … [The sailors] throng about the captain, begging and praying him to commit the helm to them … and if at any time they do not prevail … they mutiny and take possession of the ship and make free with the stores; thus, eating and drinking, they proceed on their voyage in such a manner as might be expected of them.
Here Plato asks a natural question. Suppose that running a country is like running a ship: it is an art that requires years of practice, and an art which some people, like ship captains, are better suited for than others. We would not want to put everyone in charge of a ship. We think that the best qualified people should run the ship for the benefit of everyone else. Why, then, would we want everyone to be in charge of governing? Wouldn’t it be better to allow people to vote only on the topics they are well informed about?
Plato’s dim view of the wisdom of crowds was echoed by many later writers. Thoreau held that “The mass never comes up to the standard of its best member, but on the contrary degrades itself to a level with the lowest.” And Nietzsche quipped that “Madness is the exception in individuals but the rule in groups”.
There is emerging evidence that in many situations, crowds are in fact wiser than their members. The British scientist Francis Galton once observed farmers guessing the weight of an ox at the county fair. As usual, many guesses were far too low and others were quite high. But when Galton averaged their guesses together, he discovered something surprising. The average guess was that the ox weighted 1,197 pounds. The ox’s actual weight? 1,198 pounds.
This insight is at the core of the field of judgment aggregation. By collecting a number of opinions and combining them together, we can often produce an opinion which is more accurate than most or even all of its members.
This view of democracy is reflected in Plato’s student Aristotle, who took a sunnier view of the wisdom of crowds. Aristotle wrote:
There is this to be said for the many: each of them by himself may not be of a good quality, but when they all come together it is possible that they may surpass – collectively, and as a body, although not individually – the quality of the few best.
What does judgment aggregation have to do with democracy? One of the foundational results of judgment aggregation is the Condorcet Jury Theorem. Imagine a jury of members who make up their minds independently about some matter p, for example whether to convict John Doe or whether to elect Trump for a second term. Suppose that each of the members is at least slightly more likely to be correct than incorrect about p. Then as the group grows in size, the probability that the verdict chosen by majority vote among the jury members is correct grows rapidly towards 100%.
Judgment aggregation theory makes a strong case for the value of democracy: all of us together can often produce better judgments than even the smartest of us, acting alone. Perhaps we can even design new voting systems to help us make better decisions.
Another reason to think that democratic deliberation and voting produces good decisions comes from the study of reasoning and argumentation. There is emerging evidence that reasoning is not adapted for solitary use, but in fact emerged as a tool for constructing arguments to convince others of our views. On this view, reasoning functions well in group deliberation where arguments can be produced and evaluated by neutral parties. But when we reason by ourselves or in small, likeminded groups of experts, reasoning becomes maladaptive, leading to bias and error. With no adversary to contest our views, our reasonings are more extreme versions of the beliefs that we already hold.
Consider the infamous Bay of Pigs invasion. In 1961, the United States armed a small group of 1,400 Cuban exiles and sent them into Cuba to overthrow the Cuban government. The exiles found themselves badly outnumbered, and within 24 hours they had all been killed or captured. How did the United States government ever come to believe that 1,400 rebels could topple a government?
The answer is groupthink: the decision to invade was made by a very select group of likeminded policy officials who were extremely resistant to hearing their opinions questioned. Lacking any effective challenge to their position, these officials quickly argued themselves into a wildly optimistic view of the justice of their plan and the likelihood that it would succeed. If the decision had been taken democratically, it would have quickly become apparent that the arguments in favor of invasion were weak, and the decision to invade Cuba would never have been made.
There is a third advantage to democratic deliberation, and this is that it helps us to discover new ideas and plans for implementing them. Some of the best evidence for this fact comes from the Diversity Trumps Ability Theorem of Lu Hong and Scott Paige.
Suppose you are solving a problem and you can pick ten people to help you. Who should you choose? One thing you might do is to choose the ten best experts. They are experts, after all. Another thing you might do is to choose ten random people. Why would you do such a thing, you ask? Because, as Hong and Paige prove, under many conditions the randomly selected team will outperform the team of experts.
The explanation for this result is that diversity trumps ability in problem solving. Experts are often likeminded, so a team of ten experts may not do much better than one expert alone. By contrast, randomly selected groups are diverse, and each member of the group will have something new to contribute. Although one expert is surely better than one randomly selected person, ten experts may not be better than ten people.
This logic can be extended to argue for the importance of diversity in solving political problems. By allowing all of the many diverse groups in society to solve problems together, we pool our resources and discover new solutions that can be tested and implemented with the help of policy experts. If decisions were made by experts alone, they would miss many important solutions that could only be solved by the fresh thinking of a diverse group.
None of this is meant to suggest that democracy is a panacea. Democracies sometimes make poor choices, even terrible choices. But at the end of the day, democratic deliberation and voting is a good bet for societies looking to make sound policy decisions.
