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Friday, February 16, 2018

The Promise of Smart Contracts

Blockchain technology and other advances help expand our ability to make enforceable agreements without the state.

Jerry, we’re not just going to
give you seven hundred and fifty
thousand dollars.

What the heck were you thinkin’?
Heck, if I’m only gettin’ bank
interest, I’d look for complete
security. Heck, FDIC. I don’t
see nothin’ like that here.

Yah, but I — okay, I would, I’d
guarantee ya your money back.

I’m not talkin’ about your damn
word, Jerry.

                                             Fargo (1996)

Fargo is primarily a movie about promises, implicit and explicit. It asks whether we will keep our promises to others, even against our own self-interest. What makes the movie fascinating is that many of the promises aren’t backed by the court system, for very good reason — the deals are illegal. Fargo asks if we can trust each other even if there is no government force making us comply. In other words, can we make contracts in the state of nature? In 1651, Hobbes argued that we couldn’t:

“If a covenant be made wherein neither of the parties perform presently, but trust one another, in the condition of mere nature (which is a condition of war of every man against every man) upon any reasonable suspicion, it is void: but if there be a common power set over them both, with right and force sufficient to compel performance, it is not void. For he that performeth first has no assurance the other will perform after, because the bonds of words are too weak to bridle men’s ambition, avarice, anger, and other passions, without the fear of some coercive power…”

In other words, we need some external mechanism to enforce our promises, to make it so that other people can depend on our commitment. Making credible commitments is the foundation of business and society in general. Like Hobbes, we tend to assume that the government’s coercive power is the only way to create contracts. Nobel Prize-winning economist Oliver Williamson called this view legal centralism, the assumption that “the legal system enforces promises in a knowledgeable, sophisticated, and low-cost way” (Williamson, 1996, 121).

Williamson and other Nobel laureates, such as Elinor Ostrom, built their careers on proving this assumption wrong. In many instances, the court system is costly and time-consuming, and sometimes corrupt. Moreover, people are often surprisingly able to enforce promises and maintain order in their own communities without government.

Promises, Promises

Reputation is extremely useful in small communities with repeated transactions. Trust is the bedrock of society. Without it, life would look a lot like Hobbes’ state of nature — constant suspicion, backstabbing, and insecurity. A person might make a promise, but given the opportunity, they might break it and pursue their own self-interest, a scenario which Williamson calls opportunism. However, business deals depend on being able to trust that a promise will be kept, otherwise our society would be limited to instantaneous exchanges. Fortunately, there are a number of mechanisms that can be used to secure a promise, all of which have advantages and disadvantages [1].

For instance, we might depend on personal ethics and only make promises with people who have a strict moral code. The advantage of relying on personal ethics is that they don’t require institutions or outside coercion, but ethics also have a severe limitation: it’s difficult to know very many people well enough to trust them to do the right thing, and even the best people might break their promises.

Another enforcement mechanism is reputation. Before making a contract with someone, we can ask around and find out how their previous interactions went. Reputation is extremely useful in small communities with repeated transactions since, if someone breaks their promise, they will be labeled untrustworthy and will be excluded from future interactions. However, reputation is more difficult to apply when interacting with strangers.

Other enforcement mechanisms for promises include strategies like vertical integration in business (where opportunism is curbed through the alignment of incentives) and the use of collateral.

The Internet Problem

But the Internet, currently a state of nature if there ever was one, presents new difficulties. Personal ethics, of course, are always helpful, but there is no guarantee that a random stranger will be ethical. Reputation is more difficult because pseudonyms like email addresses and usernames are often used instead of true names. When a person breaks their promise, they can simply erase their history by creating a new pseudonym with a clean reputation.

It’s clear that many of the enforcement mechanisms are hard to apply to the Internet. Being able to cheaply create a new pseudonym in order to dodge a bad reputation is called whitewashing (Nisan 2007, 682). There are various ways to handle the problem of whitewashing. One is to distrust all newcomers since they could have a new identity to hide a bad reputation. Another possibility is to ensure that any pseudonym is tied to a real person or business so that a bad reputation can’t be escaped.

So why don’t we just create a global reputation system connected to our real-life identities? China is doing just that. As Wired explains, people with low ratings (including those who speak out against the government) will be punished in nearly every aspect of their lives: slower internet speeds, restricted access to restaurants, and the removal of the right to travel. They will have extreme difficulty being hired, renting apartments, and getting loans. In other words, a global reputation system can become less about trustworthiness and more about allegiance to authority.

It’s clear that many of the enforcement mechanisms are hard to apply to the Internet. Personal ethics are ideal but unreliable. Reputation systems that attempt to enforce societal or organizational norms must be carefully designed lest they turn into “basically a big data gamified version of the Communist Party’s surveillance methods” (Botsman 2017).

Lastly, laws cannot be easily applied to people in different countries, since each geographic jurisdiction has its own separate legal system, and there’s little chance of forcing a person from the Internet (especially if they are anonymous) to appear in court in a different country.

A Tool Is Only Good if It’s Useful

We tend to forget that there is such a thing as technological progress in contracts. It is important to realize that all of our enforcement mechanisms are merely tools to be used when helpful. Like a hammer or a screwdriver, each tool might apply in a different situation. Moreover, like tools, our enforcement mechanisms are subject to innovation. For hundreds of years, since Hobbes, we’ve tended to think of contracts as legal agreements that must be enforced by the court system. However, court enforcement is only one of many ways to enforce promises, and we need to hold open the possibility that we can improve on it.

As public choice economist Gordon Tullock pointed out, “We tend to forget that there is such a thing as technological progress in contracts. People discover new ways of making agreements, and over a period of time we obtain considerable benefit from this sort of technological progress” (Tullock 1970).

One such example of technological progress is the invention of smart contracts. Smart contracts are a new mechanism for enforcing promises, allowing us to make credible commitments with each other on a blockchain, including commitments with strangers in other countries. To be clear, smart contracts are not legally enforceable, but that’s part of their unique advantage. Smart contract commitments are enforced outside of the law, outside of legal jurisdictions, without government enforcement.

Given that our legal jurisdictions are primarily tied to our geographic location, and many countries have frail or unreliable legal institutions, this is a huge societal advance. It means that given an Internet connection, someone from one of the poorest countries in the world can make business deals and credible commitments with someone in the US as easily as if they were American. By creating trust where there was none, the world will be opened like never before.

Smart Contracts

Smart contracts are immutable, meaning that the code by default cannot be changed. The idea of smart contracts originated in the mid-90s when programmer and legal scholar Nick Szabo published a series of articles explaining their potential [2]. Like a vending machine, smart contracts rely on machinery for enforcement. However, instead of using physical machinery, smart contracts are literally code that runs on a blockchain, a kind of open, distributed ledger that runs on the computers of thousands of users, and which has no central authority.

Contrary to their name, smart contracts have nothing to do with artificial intelligence. “Smart” refers to their self-enforcing quality. Smart contracts are immutable, meaning that the code by default cannot be changed. For the purposes of the contract, this is a good thing, since it’s impossible to break a promise if you have no opportunity to do so.

However, for programmers, immutability presents a special challenge. All code has bugs, and code that cannot be altered needs to be written carefully to try to minimize the number of mistakes since the bugs can’t be fixed after the fact. Thus, writing a smart contract is like trying to write code for NASA — correctness matters a great deal, and the consequences of bad code can be dire.

Smart contracts cannot access outside information unless it is written to the blockchain. A smart contract might be as simple as a transfer of money from one account to another after a certain time, or it might be very complicated. However, one major limitation is that smart contracts can only transfer digital assets that are defined on a blockchain, such as cryptocurrencies. This might seem like a show-stopper given that cryptocurrencies aren’t yet widely accepted, but transferring money subject to certain conditions is all that many contracts do. Also, even contracts that include actions with physical objects can potentially be enforced by putting up bonds that will be lost if the promise isn’t kept.

Another limitation is that smart contracts cannot access outside information unless it is written to the blockchain. For instance, a smart contract by itself has no access to weather data. To condition a contract on the temperature, for example, there must be a third party that takes the data from a weather API and writes it to the blockchain in a way that is accessible to other users. This trusted data source is called an oracle.

There Are Advantages and Drawbacks

Smart contracts have many limitations. However, we tend to forget that the courts have limitations as well. We shouldn’t compare smart contracts to an idealized version of court-enforced contracts. When we view both critically, it becomes clear that court-enforced contracts have intrinsic flaws. First, access to the court system is rationed, and there are many people waiting for their turn simply to use the service. This means that cases may take years or even decades. Because of the slowness of the courts, businesses often use private arbitration clauses in their contracts that allow them to settle out of court.

Another often-overlooked limitation of the court system is that because the court is an external third party, it can only guess at the true damages if the contract is breached. This is problematic because the court system determines what will be given to the aggrieved party.

Even in countries with the best institutions, court-enforced contracts have intrinsic limitations and paternalistic aims. Unfortunately, simply asking the aggrieved party how much the performance of the contract was worth to them isn’t going to work — they have no incentive to be honest in reporting their damages. Therefore, the court system tries to use its best judgment to determine what the damages are, but as Georgetown Law professor Randy Barnett points out, “Any assessment of legal damages attempts to quantity or objectify that which is actually subjective and essentially unmeasurable…” (Barnett 2010).  

The solution is for the parties to write their valuations explicitly in the contract, as liquidated damages. However, the courts may decide not to enforce these if they think they are unfair. Thus, even in countries with the best institutions, court-enforced contracts have intrinsic limitations and paternalistic aims.

Smart contracts are not legal contracts, and in many cases may not be a good replacement for legal contracts. However, they are a valuable new tool in our limited toolbox. They allow us to make commitments — even with strangers — without government enforcement, something many, for hundreds of years, have assumed was impossible. In the next few decades, smart contracts will give people around the world the power to make agreements with each other despite corrupt and broken institutions, and so transform the lives of millions.


  1. In Order Without Law: How Neighbors Settle Disputes (Ellickson 1991), Yale Law Professor Robert C. Ellickson studied how cattle ranchers in rural Shasta County, California enforced their promises, and categorizes some of the constraints on behavior thusly: personal ethics, contracts, norms, organization rules, and law. Anthony T. Kronman, also a Yale Law Professor, wrote about the ability to make contracts without using court enforcement in Contract Law and the State of Nature (Kronman 1985). He describes a number of devices, such as “hostages,” collateral, hand-tying, and the alignment of incentives by union. 
  2. One of the primary pieces is Formalizing and Securing Relationships on Public Networks (Szabo 1997). 

Works Cited

  1. Barnett, Randy E. The Oxford Introductions to U.S. Law: Contracts. Oxford: Oxford University Press, 2010.
  2. Botsman, Rachel. “Big data meets Big Brother as China moves to rate its citizens.” WIRED. November 28, 2017. Accessed February 05, 2018.
  3. Ellickson, Robert C. Order Without Law: How Neighbors Settle Disputes. Cambridge, MA: Harvard University Press, 1991.
  4. Hobbes, Thomas, and J. C. A. Gaskin. Leviathan. Oxford: Oxford University Press, 1998.
  5. Kronman, Anthony T. “Contract Law and the State of Nature.” Journal of Law, Economics, & Organization 1, no. 1 (1985): 5-32.
  6. Nisan, Noam, Tim Roughgarden, Éva Tardos, Vijay V. Vazirani, and Christos H. Papadimitriou. Algorithmic Game Theory. New York: Cambridge University Press, 2008.
  7. Szabo, Nick. “Formalizing and Securing Relationships on Public Networks.” First Monday. September 1, 1997. Accessed February 05, 2018.
  8. Tullock, Gordon. Private Wants, Public Means: An economic analysis of the desirable scope of government. New York: Basic Books, Inc, 1970.
  9. Williamson, Oliver E. The Mechanisms of Governance. New York: Oxford Univ. Press, 1996.

Reprinted from

  • Kate Sills holds degrees in Computer Science and Cognitive Science from UC Berkeley.