Tag: Gregory Mankiw

The Fairness Principle: How the Veil of Ignorance Helps Test Fairness

“But the nature of man is sufficiently revealed for him to know something of himself and sufficiently veiled to leave much impenetrable darkness, a darkness in which he ever gropes, forever in vain, trying to understand himself.”

— Alexis de Tocqueville, Democracy in America

The Basics

If you could redesign society from scratch, what would it look like?

How would you distribute wealth and power?

Would you make everyone equal or not? How would you define fairness and equality?

And — here’s the kicker — what if you had to make those decisions without knowing who you would be in this new society?

Philosopher John Rawls asked just that in a thought experiment known as “the Veil of Ignorance” in his 1971 book, Theory of Justice.

Like many thought experiments, the Veil of Ignorance could never be carried out in the literal sense, nor should it be. Its purpose is to explore ideas about justice, morality, equality, and social status in a structured manner.

The Veil of Ignorance, a component of social contract theory, allows us to test ideas for fairness.

Behind the Veil of Ignorance, no one knows who they are. They lack clues as to their class, their privileges, their disadvantages, or even their personality. They exist as an impartial group, tasked with designing a new society with its own conception of justice.

As a thought experiment, the Veil of Ignorance is powerful because our usual opinions regarding what is just and unjust are informed by our own experiences. We are shaped by our race, gender, class, education, appearance, sexuality, career, family, and so on. On the other side of the Veil of Ignorance, none of that exists. Technically, the resulting society should be a fair one.

In Ethical School Leadership, Spencer J. Maxcy writes:

Imagine that you have set for yourself the task of developing a totally new social contract for today's society. How could you do so fairly? Although you could never actually eliminate all of your personal biases and prejudices, you would need to take steps at least to minimize them. Rawls suggests that you imagine yourself in an original position behind a veil of ignorance. Behind this veil, you know nothing of yourself and your natural abilities, or your position in society. You know nothing of your sex, race, nationality, or individual tastes. Behind such a veil of ignorance all individuals are simply specified as rational, free, and morally equal beings. You do know that in the “real world,” however, there will be a wide variety in the natural distribution of natural assets and abilities, and that there will be differences of sex, race, and culture that will distinguish groups of people from each other.

“The Fairness Principle: When contemplating a moral action, imagine that you do not know if you will be the moral doer or receiver, and when in doubt err on the side of the other person.”

— Michael Shermer, The Moral Arc: How Science and Reason Lead Humanity Toward Truth, Justice, and Freedom

The Purpose of the Veil of Ignorance

Because people behind the Veil of Ignorance do not know who they will be in this new society, any choice they make in structuring that society could either harm them or benefit them.

If they decide men will be superior, for example, they must face the risk that they will be women. If they decide that 10% of the population will be slaves to the others, they cannot be surprised if they find themselves to be slaves. No one wants to be part of a disadvantaged group, so the logical belief is that the Veil of Ignorance would produce a fair, egalitarian society.

Behind the Veil of Ignorance, cognitive biases melt away. The hypothetical people are rational thinkers. They use probabilistic thinking to assess the likelihood of their being affected by any chosen measure. They possess no opinions for which to seek confirmation. Nor do they have any recently learned information to pay undue attention to. The sole incentive they are biased towards is their own self-preservation, which is equivalent to the preservation of the entire group. They cannot stereotype any particular group as they could be members of it. They lack commitment to their prior selves as they do not know who they are.

So, what would these people decide on? According to Rawls, in a fair society all individuals must possess the following:

  • Rights and liberties (including the right to vote, the right to hold public office, free speech, free thought, and fair legal treatment)
  • Power and opportunities
  • Income and wealth sufficient for a good quality of life (Not everyone needs to be rich, but everyone must have enough money to live a comfortable life.)
  • The conditions necessary for self-respect

For these conditions to occur, the people behind the Veil of Ignorance must figure out how to achieve what Rawls regards as the two key components of justice:

  • Everyone must have the best possible life which does not cause harm to others.
  • Everyone must be able to improve their position, and any inequalities must be present solely if they benefit everyone.

However, the people behind the Veil of Ignorance cannot be completely blank slates or it would be impossible for them to make rational decisions. They understand general principles of science, psychology, politics, and economics. Human behavior is no mystery to them. Neither are key economic concepts, such as comparative advantage and supply and demand. Likewise, they comprehend the deleterious impact of social entropy, and they have a desire to create a stable, ordered society. Knowledge of human psychology leads them to be cognizant of the universal desire for happiness and fulfillment. Rawls considered all of this to be the minimum viable knowledge for rational decision-making.

Ways of Understanding the Veil of Ignorance

One way to understand the Veil of Ignorance is to imagine that you are tasked with cutting up a pizza to share with friends. You will be the last person to take a slice. Being of sound mind, you want to get the largest possible share, and the only way to ensure this is to make all the slices the same size. You could cut one huge slice for yourself and a few tiny ones for your friends, but one of them might take the large slice and leave you with a meager share. (Not to mention, your friends won’t think very highly of you.)

Another means of appreciating the implications of the Veil of Ignorance is by considering the social structures of certain species of ants. Even though queen ants are able to form colonies alone, they will band together to form stronger, more productive colonies. Once the first group of worker ants reaches maturity, the queens fight to the death until one remains. When they first form a colony, the queen ants are behind a Veil of Ignorance. They do not know if they will be the sole survivor or not. All they know, on an instinctual level, is that cooperation is beneficial for their species. Like the people behind the Veil of Ignorance, the ants make a decision which, by necessity, is selfless.

The Veil of Ignorance, as a thought experiment, shows us that ignorance is not always detrimental to a society. In some situations, it can create robust social structures. In the animal kingdom, we see many examples of creatures that cooperate even though they do not know if they will suffer or benefit as a result. In a paper entitled “The Many Selves of Social Insects,” Queller and Strassmann write of bees:

…social insect colonies are so tightly integrated that they seem to function as single organisms, as a new level of self. The honeybees' celebrated dance about food location is just one instance of how their colonies integrate and act on information that no single individual possesses. Their unity of purpose is underscored by the heroism of workers, whose suicidal stinging attacks protect the single reproducing queen.

We can also consider the Tragedy of the Commons. Introduced by ecologist Garrett Hardin, this mental model states that shared resources will be exploited if no system for fair distribution is implemented. Individuals have no incentive to leave a share of free resources for others. Hardin’s classic example is an area of land which everyone in a village is free to use for their cattle. Each person wants to maximize the usefulness of the land, so they put more and more cattle out to graze. Yet the land is finite and at some point will become too depleted to support livestock. If the people behind the Veil of Ignorance had to choose how the common land should be shared, the logical decision would be to give each person an equal part and forbid them from introducing too many cattle.

As N. Gregory Mankiw writes in Principles of Microeconomics:

The Tragedy of the Commons is a story with a general lesson: when one person uses a common resource, he diminishes other people's enjoyment of it. Because of this negative externality, common resources tend to be used excessively. The government can solve the problem by reducing use of the common resource through regulation or taxes. Alternatively, the government can sometimes turn the common resource into a private good.

This lesson has been known for thousands of years. The ancient Greek philosopher Aristotle pointed out the problem with common resources: “What is common to many is taken least care of, for all men have greater regard for what is their own than for what they possess in common with others.”

In The Case for Meritocracy, Michael Faust uses other thought experiments to support the Veil of Ignorance:

Let’s imagine another version of the thought experiment. If inheritance is so inherently wonderful — such an intrinsic good — then let’s collect together all of the inheritable money in the world. We shall now distribute this money in exactly the same way it would be distributed in today’s world… but with one radical difference. We are going to distribute it by lottery rather than by family inheritance, i.e, anyone in the world can receive it. So, in these circumstances, how many people who support inheritance would go on supporting it? Note that the government wouldn’t be getting the money… just lucky strangers. Would the advocates of inheritance remain as fiercely committed to their cherished principle? Or would the entire concept instantly be exposed for the nonsense it is?

If inheritance were treated as the lottery it is, no one would stand by it.


In the world of the 1% versus the 99%, no one in the 1% would ever accept a lottery to decide inheritance because there would be a 99% chance they would end up as schmucks, exactly like the rest of us.

And a further surrealistic thought experiment:

Imagine that on a certain day of the year, each person in the world randomly swaps bodies with another person, living anywhere on earth. Well, for the 1%, there’s a 99% chance that they will be swapped from heaven to hell. For the 99%, 1% might be swapped from hell to heaven, while the other 98% will stay the same as before. What kind of constitution would the human race adopt if annual body swapping were a compulsory event?! They would of course choose a fair one.

“In the immutability of their surroundings the foreign shores, the foreign faces, the changing immensity of life, glide past, veiled not by a sense of mystery but by a slightly disdainful ignorance.”

— Joseph Conrad, Heart of Darkness

The History of Social Contract Theory

Although the Veil of Ignorance was first described by Rawls in 1971, many other philosophers and writers have discussed similar concepts in the past. Philosophers discussed social contract theory as far back as ancient Greece.

In Crito, Plato describes a conversation in which Socrates discusses the laws of Athens and how they are responsible for his existence. Finding himself in prison and facing the death penalty, Socrates rejects Crito’s suggestion that he should escape. He states that further injustice is not an appropriate response to prior injustice. Crito believes that by refusing to escape, Socrates is aiding his enemies, as well as failing to fulfil his role as a father. But Socrates views the laws of Athens as a single entity that has always protected him. He describes breaking any of the laws as being like injuring a parent. Having lived a long, fulfilling life as a result of the social contract he entered at birth, he has no interest in now turning away from Athenian law. Accepting death is essentially a symbolic act that Socrates intends to use to illustrate rationality and reason to his followers. If he were to escape, he would be acting out of accord with the rest of his life, during which he was always concerned with justice.

Social contract theory is concerned with the laws and norms a society decides on and the obligation individuals have to follow them. Socrates’ dialogue with Plato has similarities with the final scene of Arthur Miller’s The Crucible. At the end of the play, John Proctor is hung for witchcraft despite having the option to confess and avoid death. In continuing to follow the social contract of Salem and not confessing to a crime he obviously did not commit, Proctor believes that his death will redeem his earlier mistakes. We see this in the final dialogue between Reverend Hale and Elizabeth (Proctor's wife):

HALE: Woman, plead with him! […] Woman! It is pride, it is vanity. […] Be his helper! What profit him to bleed? Shall the dust praise him? Shall the worms declare his truth? Go to him, take his shame away!


ELIZABETH: […] He have his goodness now. God forbid I take it from him!

In these two situations, individuals allow themselves to be put to death in the interest of following the social contract they agreed upon by living in their respective societies. Earlier in their lives, neither person knew what their ultimate fate would be. They were essentially behind the Veil of Ignorance when they chose (consciously or unconsciously) to follow the laws enforced by the people around them. Just as the people behind the Veil of Ignorance must accept whatever roles they receive in the new society, Socrates and Proctor followed social contracts. To modern eyes, the decision both men make to abandon their children in the interest of proving a point is not easily defensible.

Immanuel Kant wrote about justice and freedom in the late 1700s. Kant believed that fair laws should not be based on making people happy or reflecting the desire of individual policymakers, but should be based on universal moral principles:

Is it not of the utmost necessity to construct a pure moral philosophy which is completely freed from everything that may be only empirical and thus belong to anthropology? That there must be such a philosophy is self-evident from the common idea of duty and moral laws. Everyone must admit that a law, if it is to hold morally, i.e., as a ground of obligation, must imply absolute necessity; he must admit that the command, “Then shalt not lie,” does not apply to men only, as if other rational beings had no need to observe it. The same is true for all other moral laws properly so called. He must concede that the ground of obligation here must not be sought in the nature of man or in the circumstances in which he is placed, but sought a priori solely in the concepts of pure reason, and that every other precept which is in certain respects universal, so far as it leans in the least on empirical grounds (perhaps only in regard to the motive involved), may be called a practical rule but never a moral law.

How We Can Apply This Concept

We can use the Veil of Ignorance to test whether a certain issue is fair.

When my kids are fighting over the last cookie, which happens more often than you'd imagine, I ask them to determine who will spilt the cookie. The other person picks. This is the old playground rule, “you split, I pick.” Without this rule, one of them would surely give the other a smaller portion. With it, the halves are as equal as they would be with sensible adults.

When considering whether we should endorse a proposed law or policy, we can ask: if I did not know if this would affect me or not, would I still support it? Those who make big decisions that shape the lives of large numbers of people are almost always those in positions of power. And those in positions of power are almost always members of privileged groups. As Benjamin Franklin once wrote: “Justice will not be served until those who are unaffected are as outraged as those who are.”

Laws allowing or prohibiting abortion have typically been made by men, for example. As the issue lacks real significance in their personal lives, they are free to base decisions on their own ideological views, rather than consider what is fair and sane. However, behind the Veil of Ignorance, no one knows their sex. Anyone deciding on abortion laws would have to face the possibility that they themselves will end up as a woman with an unwanted pregnancy.

In Justice as Fairness: A Restatement, Rawls writes:

So what better alternative is there than an agreement between citizens themselves reached under conditions that are fair for all?


[T]hreats of force and coercion, deception and fraud, and so on must be ruled out.


Deep religious and moral conflicts characterize the subjective circumstances of justice. Those engaged in these conflicts are surely not in general self-interested, but rather, see themselves as defending their basic rights and liberties which secure their legitimate and fundamental interests. Moreover, these conflicts can be the most intractable and deeply divisive, often more so than social and economic ones.


In Ethics: Studying the Art of Moral Appraisal, Ronnie Littlejohn explains:

We must have a mechanism by which we can eliminate the arbitrariness and bias of our “situation in life” and insure that our moral standards are justified by the one thing all people share in common: reason. It is the function of the veil of ignorance to remove such bias.

When we have to make decisions that will affect other people, especially disadvantaged groups (such as when a politician decides to cut benefits or a CEO decides to outsource manufacturing to a low-income country), we can use the Veil of Ignorance as a tool for making fair choices.

As Robert F. Kennedy (the younger brother of John F. Kennedy) said in the 1960s:

Few will have the greatness to bend history itself, but each of us can work to change a small portion of events. It is from numberless diverse acts of courage and belief that human history is shaped. Each time a man stands up for an ideal, or acts to improve the lot of others, or strikes out against injustice, he sends forth a tiny ripple of hope, and crossing each other from a million different centers of energy and daring, those ripples build a current which can sweep down the mightiest walls of oppression and resistance.

When we choose to position ourselves behind the Veil of Ignorance, we have a better chance of creating one of those all-important ripples.

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How (Supposedly) Rational People Make Decisions

There are four principles that Gregory Mankiw outlines in his multi-disciplinary economics textbook Principles of Economics.

I got the idea for reading an Economics textbook from Charlie Munger, the billionaire business partner of Warren Buffett. He said:

Economics was always more multidisciplinary than the rest of soft science. It just reached out and grabbed things as it needed to. And that tendency to just grab whatever you need from the rest of knowledge if you’re an economist has reached a fairly high point in Mankiw’s new textbook Principles of Economics. I checked out that textbook. I must have been one of the few businessmen in America that bought it immediately when it came out because it had gotten such a big advance. I wanted to figure out what the guy was doing where he could get an advance that great. So this is how I happened to riffle through Mankiw’s freshman textbook. And there I found laid out as principles of economics: opportunity cost is a superpower, to be used by all people who have any hope of getting the right answer. Also, incentives are superpowers.

So we know that we can add Opportunity cost and incentives to our list of Mental Models.

Let's dig in.

Principle 1: People Face Trade-offs

You have likely heard the old saying, “There is no such thing as a free lunch.” There is much to this old adage and it's one we often forget when making decisions. To get more of something we like we almost always have to give up something else we like. A good heuristic in life is that if someone offers you something for nothing, turn it down.

Making decisions requires trading off one goal against another.

Consider a student who must decide how to allocate her most valuable resource—her time. She can spend all of her time studying economics, spend all of it studying psychology, or divide it between the two fields. For every hour she studies one subject, she gives up an hour she could have used studying the other. And for every hour she spends studying, she gives up an hour that she could have spent napping, bike riding, watching TV, or working at her part-time job for some extra spending money.

Or consider parents deciding how to spend their family income. They can buy food, clothing, or a family vacation. Or they can save some of the family income for retirement or for children’s college education. When they choose to spend an extra dollar on one of these goods, they have one less dollar to spend on some other good.

These are rather simple examples but Mankiw offers some more complicated ones. Consider the trade-off that society faces between efficiency and equality.

Efficiency means that society is getting the maximum benefits from its scarce resources. Equality means that those benefits are distributed uniformly among society’s members. In other words, efficiency refers to the size of the economic pie, and equality refers to how the pie is divided into individual slices.

When government policies are designed, these two goals often conflict. Consider, for instance, policies aimed at equalizing the distribution of economic well-being. Some of these policies, such as the welfare system or unemployment insurance, try to help the members of society who are most in need. Others, such as the individual income tax, ask the financially successful to contribute more than others to support the government. Though they achieve greater equality, these policies reduce efficiency. When the government redistributes income from the rich to the poor, it reduces the reward for working hard; as a result, people work less and produce fewer goods and services. In other words, when the government tries to cut the economic pie into more equal slices, the pie gets smaller.

Principle 2: The Cost of Something Is What You Give Up to Get It

Because of trade-offs, people face decisions between the costs and benefits of one course of action and the cost and benefits of another course. But costs are not as obvious as they might first appear — we need to apply some second-level thinking:

Consider the decision to go to college. The main benefits are intellectual enrichment and a lifetime of better job opportunities. But what are the costs? To answer this question, you might be tempted to add up the money you spend on tuition, books, room, and board. Yet this total does not truly represent what you give up to spend a year in college.

There are two problems with this calculation. First, it includes some things that are not really costs of going to college. Even if you quit school, you need a place to sleep and food to eat. Room and board are costs of going to college only to the extent that they are more expensive at college than elsewhere. Second, this calculation ignores the largest cost of going to college—your time. When you spend a year listening to lectures, reading textbooks, and writing papers, you cannot spend that time working at a job. For most students, the earnings they give up to attend school are the single largest cost of their education.

The opportunity cost of an item is what you give up to get that item. When making any decision, decision makers should be aware of the opportunity costs that accompany each possible action. In fact, they usually are. College athletes who can earn millions if they drop out of school and play professional sports are well aware that the opportunity cost of their attending college is very high. It is not surprising that they often decide that the benefit of a college education is not worth the cost.

Principle 3: Rational People Think at the Margin

For the sake of simplicity economists normally assume that people are rational. While this causes many problems, there is an undercurrent of truth to the fact that people systematically and purposefully “do the best they can to achieve their objectives, given opportunities.” There are two parts to rationality. The first is that your understanding of the world is correct. Second you maximize the use of your resources toward your goals.

Rational people know that decisions in life are rarely black and white but usually involve shades of gray. At dinnertime, the question you face is not “Should I fast or eat like a pig?” More likely, you will be asking yourself “Should I take that extra spoonful of mashed potatoes?” When exams roll around, your decision is not between blowing them off and studying twenty-four hours a day but whether to spend an extra hour reviewing your notes instead of watching TV. Economists use the term marginal change to describe a small incremental adjustment to an existing plan of action. Keep in mind that margin means “edge,” so marginal changes are adjustments around the edges of what you are doing. Rational people often make decisions by comparing marginal benefits and marginal costs.

Thinking at the margin works for business decisions.

Consider an airline deciding how much to charge passengers who fly standby. Suppose that flying a 200-seat plane across the United States costs the airline $100,000. In this case, the average cost of each seat is $100,000/200, which is $500. One might be tempted to conclude that the airline should never sell a ticket for less than $500. But a rational airline can increase its profits by thinking at the margin. Imagine that a plane is about to take off with 10 empty seats and a standby passenger waiting at the gate is willing to pay $300 for a seat. Should the airline sell the ticket? Of course, it should. If the plane has empty seats, the cost of adding one more passenger is tiny. The average cost of flying a passenger is $500, but the marginal cost is merely the cost of the bag of peanuts and can of soda that the extra passenger will consume. As long as the standby passenger pays more than the marginal cost, selling the ticket is profitable.

This also helps answer the question of why diamonds are so expensive and water is so cheap.

Humans need water to survive, while diamonds are unnecessary; but for some reason, people are willing to pay much more for a diamond than for a cup of water. The reason is that a person’s willingness to pay for a good is based on the marginal benefit that an extra unit of the good would yield. The marginal benefit, in turn, depends on how many units a person already has. Water is essential, but the marginal benefit of an extra cup is small because water is plentiful. By contrast, no one needs diamonds to survive, but because diamonds are so rare, people consider the marginal benefit of an extra diamond to be large.

A rational decision maker takes an action if and only if the marginal benefit of the action exceeds the marginal cost.

Principle 4: People Respond to Incentives

Incentives induce people to act. If you use a rational approach to decision making that involves trade offs and comparing costs and benefits, you respond to incentives. Charlie Munger once said: “Never, ever, think about something else when you should be thinking about the power of incentives.”

Incentives are crucial to analyzing how markets work. For example, when the price of an apple rises, people decide to eat fewer apples. At the same time, apple orchards decide to hire more workers and harvest more apples. In other words, a higher price in a market provides an incentive for buyers to consume less and an incentive for sellers to produce more. As we will see, the influence of prices on the behavior of consumers and producers is crucial for how a market economy allocates scarce resources.

Public policymakers should never forget about incentives: Many policies change the costs or benefits that people face and, as a result, alter their behavior. A tax on gasoline, for instance, encourages people to drive smaller, more fuel-efficient cars. That is one reason people drive smaller cars in Europe, where gasoline taxes are high, than in the United States, where gasoline taxes are low. A higher gasoline tax also encourages people to carpool, take public transportation, and live closer to where they work. If the tax were larger, more people would be driving hybrid cars, and if it were large enough, they would switch to electric cars.

Failing to consider how policies and decisions affect incentives often results in unforeseen results.