- Why self-interest sustains conventions
- The rowboat example
- The difference between conventions and prisoner’s dilemmas
Here are some extras for fun. Feel free to ignore this if you have had enough.
Hobbes denies that there are any natural property rights: he thinks there are no property rights outside the state and that property rights are human creations. Locke believes there are natural property rights: there are property rights in the state of nature and they come from natural law, not rules that human beings create.
Hume agrees with Hobbes that property rights are artificial, human creations and he agrees with Locke that they can exist without political authority.
Hume’s chief theoretical innovation is his theory of conventions (see ¶10). The example of the rowboat is his primary illustration of this theory. He tries to show that the situation of people who lack property rights is structurally similar to that of the two people who want to get across the river and that the system of property rights will be sustained by the same incentives that lead each person to row the boat.
There are many points where Hume can be seen as updating Hobbes. For instance, Hobes’s harsh language about human selfishness is replaced with observations about the love that people have for their families. However, the truly fundamental difference between the two comes in their descriptions of the state of nature.
Hobbes thinks that situation faced by people in the state of nature is most accurately described as what is called a prisoner’s dilemma.
Take, for example, Hobbes’s analysis of anticipatory violence. People in the state of nature have to ask themselves whether to attack one another by surprise. When they ask that question, according to Hobbes, this is what they will see. (The payoffs are Row/Column).
There is only one stable set of choices here: the northwest box (Fight, Fight). Suppose they start in the southeast box (Wait, Wait). Row will move to the northeast box (Fight, Wait) because first is better than second. And Column will move to the southwest box (Wait, Fight) for the same reason. But, of course, if both Row and Column are choosing Fight, they will wind up in the northwest box (Fight, Fight). For similar reasons, neither the northeast nor the southwest boxes are stable. Whichever one is getting the fourth best outcome from waiting while the other is fighting will switch to fighting instead.
If this is the structure of life in the state of nature each person’s best option is to attack and that explains why the state of nature is a state of war.
As Hobbes sees it, this pattern is pervasive in the state of nature. For example, it describes the choice that people in the state of nature have to make when deciding whether to take one another’s material possessions or leave them alone. That is why he believes there is no property in the state of nature.
The obvious solution is a non-aggression pact; Hobbes would call this a covenant, meaning a contract in which at least one party is trusted to do its part in the future. Row and Column could agree not to attack one another and not to take one another’s things. But, according to Hobbes, that does not really solve their problem. If they were to make such an arrangement, they would have to decide whether to keep the deal or to break it by not doing what they had promised to do.
Hobbes believes that people in a situation like this need the state to change the incentives they face and lock them into the southeast (lower right) box: waiting to use violence against others, leaving others’ possessions alone, and keeping their agreements.
Hume has a different analysis of the situation. He thinks that interactions in the state of nature are structured like case of the two people who need to cooperate in order to row a boat across a river (3.2.2, ¶10). (Remember, it’s Row/Column.)
Here there are two stable sets of choices: the northwest and southeast boxes. If they are in the southeast (Row, Row), they will stay there because neither one does any better by choosing Sit. If they are in the northeast box (Sit, Row) Column will stop rowing and instead choose Sit; that will put them in the northwest box (Sit, Sit). Similarly, if they are in the southwest box (Row, Sit) Row will stop rowing and start sitting. That will put them in the northwest box (Sit, Sit).
The people who want to get to the other side of the river do not need the state to force them to row. They can form a convention of rowing and, once each one is doing their part in the convention, neither will have an incentive to stop.
Similarly, the obvious solution to the problem of maintaining the stability of material goods in the state of nature is to agree to rules establishing property rights. Once those rules are established, Hume thinks, no one will have any incentive to stop respecting them. (As always, it’s row/column)
People in the state of nature, as Hume sees it, do not have a dominant strategy. Rather, what it makes sense for one person to do depends on what others do. There is no sense in respecting property rights if others do not do the same; so the northwest box is one possible outcome. Column won’t try to move from the northwest (Take, Take) to the northeast (Take, Leave) because that would move from the second best outcome for Column to the third. The same is true for Row and moving from the northwest (Take, Take) to the southwest (Leave, Take).
But Hume, unlike Hobbes, thinks that the southeast box could be a stable outcome too, even without external coercion. Once people generally respect property rights, each individual will be better off respecting property rights also: first is best, so no one has any incentive to leave the southeast box. That is why it is a stable outcome. He calls the coordinated behavior that puts the players in the southeast box a convention. In this case, the convention is to leave one another’s possessions alone.
However note that the way I represented that was by leaving some of the payoffs in the northeast and southwest boxes as question marks. On the face of it, the question marks should be “1st.” In the northeast box, for example, Row is taking Column’s stuff and Column is not taking Row’s. If we wrote it up that way, however, we would also have to change the southeast box to 2nd/2nd and the northwest box to 3rd/3rd. Then we would have a prisoner’s dilemma.
Hume does not think that the northeast and southwest boxes are stable. So they are not genuinely available. As he sees it, the fact that either of those boxes is inferior to the northwest box for one player means that they would never exist: if one player starts taking, the other player will do the same. So he disregards the payoffs from Take in those boxes.
It is not obvious that he is correct to do so. Property is not the same as the rowboat case. If you stop rowing the boat, you stop getting what you want. If you take someone else’s stuff, you get what you want: the other person’s stuff! The sitting parties in the rowboat case are indifferent between sitting while the other player rows and sitting while the other party sits. But the player that takes someone else’s stuff is not indifferent between the box where the other player is taking too and the box where the other player is not taking. It’s far better to be the one who takes while the other one leaves.
I understand Hume’s thinking here. You wouldn’t really have someone else’s stuff and your own at the same time. If you break the property convention, so will everyone else and so the northeast and southwest boxes could not happen. But I think Hobbes might have a reasonable complaint that Hume has misrepresented what is really going on.
Suppose a group of people were in conditions of severe scarcity, meaning there is only enough of some resource for one person and everyone needs the resource to live: the only vial of the antidote, say, or the last canteen of water. Then there will be no benefits to coordination and there will be no convention about property rights. (I said the northwest box is second best because it gives each one a chance at getting the scarce good. But only one is actually going to get it, so this is a little misleading.)
There will also not be conventions in conditions of great abundance, such as the poets imagined in the Golden Age (see 3.2.2, ¶7 and ¶14–17). If everything is plentiful, there is nothing to be gained from a convention establishing property rights.
Here what either player does has no effect on the other. So there is no benefit to coordinating their behavior. Hume says this means that conventions require a moderate amount of scarcity. There has to be enough scarcity to make a convention worthwhile but not so much as to make it pointless.
How do we decide which analysis of the situation people face in the state of nature is more accurate than the other?
Hume has a lot going for him. First, property rights really are just about as obvious as rowing the boat. Second, we know that human beings existed in communities for thousands of years without the state. They must have had some way of getting along.
On the other hand, as we noted, the two cases are not exactly the same because the consequences are not as immediate in the case of property rights as they are with the rowboat case. The convention of property rights has to collapse immediately for the two cases to be the same.
Once societies reach a certain size, the connection between individual behavior and the continuation of the convention breaks down. In a large society, the rules governing property continue whether you are a thief or not. If they are going to break down, your respecting the rules will not prop them up. The more normal situation is that individual violations do not cause the rules to collapse: there is a theft happening right now, for instance, but our society’s conventions of property rights will chug along.
In these cases, the benefits of the convention of property rights are a public good (also known as a collective good; the terms are interchangeable). Public goods must be produced by some portion of a group but those who do nothing to produce the public goods cannot be excluded from enjoying them. Given the individual incentives involved, the provision of public goods poses a familiar problem. Here “cooperate” means do what is needed to produce the public good and “defect” means not doing what is needed. The row player is an individual, the column player is the group. Because the difference that an individual’s cooperation makes to the production of a public good is usually unnoticeable, I will only include payoffs for the individual (row) player.
|No public good||Public good is produced|
If the members of the group cooperate to produce the public good, the individual is better off defecting. After all, individuals get the public good whether they cooperate or not. If the members of the group do not cooperate to produce the public good, the individual is also better off defecting. There is no point in making a sacrifice for the sake of a non-existent public good. But, of course, there is no “group,” there are just lots of individuals. The obvious conclusion is that public goods will not be produced in the way that conventions arise, namely, by coordination among self-interested individuals.
So when the benefits of conventional rules become too “remote,” Hume thinks the state has to step in to do the thing Hobbes said it has to do: lock us in to the southeast box (see 3.2.7).
Locke believes that natural property rights are based on natural law and that natural law is discovered by reason. When Hume says that reason cannot be the source of the rules of property, he is attacking Locke.
Unfortunately, getting into Hume’s reasons for rejecting natural law would take us too far off course. But two points are clear enough.
First, Hume did not think it was necessary. His moral philosophy is dedicated to showing that morality can be explained as the product of human psychology and artificial conventions. If his explanation succeeds, there is no need to make assumptions about natural law, what God wants, or what rules can or cannot be discovered by reasoning about them.
Second, and more importantly, Hume thinks that there is no point to the rules of justice unless others are obeying them as well. This strongly suggests, without necessarily proving, that the rules of justice are conventional. Roughly, the only rules that do any good are the ones that everyone is obeying. The individual exercise of reason does not tell you what the rules of justice and property are. Only the conventional practices that other people are following tell you that.
Again, that does not prove that Locke is wrong. It could be that the exercise of individual reason and social convention arrive at the same solution; it could even be that reason leads the members of society to a particular solution, like the labor theory of property. But it does suggest that reason is superfluous. If conventions do all the work that is necessary, why think that reason plays any role?
Here are some extras for fun. Feel free to ignore this if you have had enough.
The name “prisoner’s dilemma” comes from a case used to illustrate it. A prosecutor offers two prisoners a deal. “If you give me enough evidence to convict the other guy, he will get an eight year sentence and you will go free. If neither of you give me any evidence, I will be able to convict both of you on a lesser charge that carries a two year sentence. But if both of you give me enough evidence to convict each other, you will each get five year sentences.” (The payoffs are Row/Column).
When people are in a prisoner’s dilemma, there is only one stable solution: the northwest (upper left) one. This reflects the fact that they each have a dominant strategy, namely, a choice that is better no matter what the other one does.
In this case, the dominant strategy is to talk. For instance, if Column decides to talk, Row will be better off talking too because a five year sentence (-5) is better than an eight year sentence (-8). And if Column decides to stay quiet, Row will be better off talking since no sentence (-0) is better than a two year sentence (-2). If we did the same thing with Column, we would get the same answer: it makes sense to talk no matter what Row does. Since both are better off talking than staying quiet, no matter what the other one does, they will wind up in the northwest box even though they would obviously be better off in the southeast box.
This is a wild strategy for beating the Prisoner’s Dilemma from the British game show Golden Balls. (My kind of game show!)
Here is the choice the players face. (The payoffs are row/column).
Strictly speaking, this is unlike the Prisoner’s Dilemma because there is no dominant strategy here. A dominant strategy is one that is rational to follow no matter what the other player does. In this case, it is better to Steal if the other player chooses Split. But if the other player chooses Steal, you will be indifferent between Stealing and Splitting yourself rather than having a rational preference for Stealing. That said, if the other player did choose to Steal, I bet you would prefer to Steal yourself rather than letting the other player get away with all the money. Just a guess.
After you watch it, listen to an interview with the participants. There is an interesting twist.
Hume refers to the poets’ description of a golden age in ¶15. His point is that in a world of great abundance, such as the golden age, there would be no conventions to create property rights because there would be no need for them. Hume was referring to classical sources, such as the Roman poets Virgil (70-19 BC) and Ovid (43 BC - 17/18 AD).
This is what David and Mary Norton say in the annotations to the edition of Hume’s Treatise that they edited.
The metaphor of a Golden Age is typically traced to Hesiod, whose golden race of men lived at a time when life on earth was idyllic. Later Roman poets recast Hesiod’s notion of a golden race into that of a Golden Age; see e.g. Virgil, Georgics 2.536; Ovid Metamorphoses 1.76–150. (Hume  2000, 544)
Here is Ovid’s Metamorphoses 1.68–150
Bk I:68-88 Humankind
He [the world’s maker -mjg] had barely separated out everything within fixed limits when the constellations that had been hidden for a long time in dark fog began to blaze out throughout the whole sky. And so that no region might lack its own animate beings, the stars and the forms of gods occupied the floor of heaven, the sea gave a home to the shining fish, earth took the wild animals, and the light air flying things.
As yet there was no animal capable of higher thought that could be ruler of all the rest. Then Humankind was born. …
Bk I:89-112 The Golden Age
This was the Golden Age that, without coercion, without laws, spontaneously nurtured the good and the true. There was no fear or punishment: there were no threatening words to be read, fixed in bronze, no crowd of suppliants fearing the judge’s face: they lived safely without protection. No pine tree felled in the mountains had yet reached the flowing waves to travel to other lands: human beings only knew their own shores. There were no steep ditches surrounding towns, no straight war-trumpets, no coiled horns, no swords and helmets. Without the use of armies, people passed their lives in gentle peace and security. The earth herself also, freely, without the scars of ploughs, untouched by hoes, produced everything from herself. Contented with food that grew without cultivation, they collected mountain strawberries and the fruit of the strawberry tree, wild cherries, blackberries clinging to the tough brambles, and acorns fallen from Jupiter’s spreading oak-tree. Spring was eternal, and gentle breezes caressed with warm air the flowers that grew without being seeded. Then the untilled earth gave of its produce and, without needing renewal, the fields whitened with heavy ears of corn. Sometimes rivers of milk flowed, sometimes streams of nectar, and golden honey trickled from the green holm oak.
Bk I:113-124 The Silver Age
When Saturn was banished to gloomy Tartarus, and Jupiter ruled the world, then came the people of the age of silver that is inferior to gold, more valuable than yellow bronze. Jupiter shortened spring’s first duration and made the year consist of four seasons, winter, summer, changeable autumn, and brief spring. Then parched air first glowed white scorched with the heat, and ice hung down frozen by the wind. Then houses were first made for shelter: before that homes had been made in caves, and dense thickets, or under branches fastened with bark. Then seeds of corn were first buried in the long furrows, and bullocks groaned, burdened under the yoke.
Bk I:125-150 The Bronze Age
Third came the people of the bronze age, with fiercer natures, readier to indulge in savage warfare, but not yet vicious. The harsh iron age was last. Immediately every kind of wickedness erupted into this age of baser natures: truth, shame and honour vanished; in their place were fraud, deceit, and trickery, violence and pernicious desires. They set sails to the wind, though as yet the seamen had poor knowledge of their use, and the ships’ keels that once were trees standing amongst high mountains, now leaped through uncharted waves. The land that was once common to all, as the light of the sun is, and the air, was marked out, to its furthest boundaries, by wary surveyors. Not only did they demand the crops and the food the rich soil owed them, but they entered the bowels of the earth, and excavating brought up the wealth it had concealed in Stygian shade, wealth that incites men to crime. And now harmful iron appeared, and gold more harmful than iron. War came, whose struggles employ both, waving clashing arms with bloodstained hands. They lived on plunder: friend was not safe with friend, relative with relative, kindness was rare between brothers. Husbands longed for the death of their wives, wives for the death of their husbands. Murderous stepmothers mixed deadly aconite, and sons inquired into their father’s years before their time. Piety was dead, and virgin Astraea, last of all the immortals to depart, herself abandoned the blood-drenched earth.
In short, Ovid is giving a story of the origins of humanity very much like you would find in Genesis: God gives us the top place in the world he has created and sets us up in a paradise of abundance. Then there is a story about humanity’s fall from paradise to what we see now. If you read on, you will see that Jupiter gets angry with humanity and floods the world. As I said, it’s very much like Genesis.
Hume, David. (1740) 1995. A Treatise of Human Nature. Edited by Mark C. Rooks. The Complete Works and Correspondence of David Hume. Charlottesville, VA: InteLex Corporation.
———. (1740) 2000. A Treatise of Human Nature. Edited by David Fate Norton and Mary Norton. Oxford: Oxford University Press.