Introduction
In our last lesson, we delved into the emotional core of negotiations by modeling compersion, jealousy, and altruism within our payoff matrices. We established that a player's utility is often a function of their partner's happiness, creating a complex web of interdependent outcomes. We now have a richer understanding of what players are trying to maximize. However, simply knowing the payoffs isn't enough, because in sequential interactions, what you promise today you might not have an incentive to deliver tomorrow.
This brings us to the central theme of today's lesson: analyzing commitment problems and the strategic value of limiting one's own future options. We will explore the "time-inconsistency problem," where a threat or promise that seems optimal to make before an action becomes suboptimal to carry out after the action. You will learn why, paradoxically, the most powerful move a player can sometimes make is to surrender their own freedom of choice, thereby making their intentions credible. This lesson draws heavily on the foundational work of Thomas Schelling, who famously argued that bargaining power is often "the power to bind oneself."
The Time-Inconsistency Problem: When Threats Ring Hollow
In strategic interactions, we constantly make threats and promises to influence others' behavior. A cuckold might threaten to end a relationship if a boundary is crossed; a hotwife might promise to provide emotional support and aftercare following a challenging date. But are these statements credible? A rational player will always look ahead and ask, "When the time comes to act, will my partner actually have an incentive to follow through?"
If the answer is no, the threat or promise is not credible and will be ignored. This is known as a commitment problem or a time-inconsistency problem.
Let's model this with a classic Entry Game, adapted to a relationship dynamic.
- Players: Anna (the Incumbent wife) and Ben (the potential Entrant into a new dynamic). The "market" is the couple's shared emotional and sexual life.
- Scenario: Ben considers exploring a new kink ("Enter"), which he finds exciting but Anna finds unsettling. Anna wants to deter him.
- The Game:
- Ben decides to
Enter(suggest the new kink) orStay Out(drop it). - If Ben Stays Out, they maintain the status quo. Payoffs: (Anna: 2, Ben: 0). Ben gets 0 because his desire is unfulfilled; Anna gets 2 for avoiding discomfort.
- If Ben Enters, Anna can either
Fight(react with anger, jealousy, and withdrawal) orAccommodate(talk it through, find a compromise).- If Anna Fights, the conflict is damaging for both. Payoffs: (Anna: -1, Ben: -1).
- If Anna Accommodates, they find a way to make it work, which is good for Ben but slightly unsettling for Anna. Payoffs: (Anna: 1, Ben: 2).
- Ben decides to
Anna's initial move is to threaten Ben: "If you bring that up, I will make our lives miserable" (i.e., "If you Enter, I will Fight"). Should Ben believe her?
To find out, we use backward induction, just as we did in previous lessons.
- Start at the end. If Ben has already Entered, Anna faces a choice: Fight or Accommodate.
- Comparing her payoffs, Accommodating (1) is better for her than Fighting (-1).
- A rational Anna will Accommodate. Her threat to Fight is not credible.
- Ben, anticipating this, knows that if he Enters, the outcome will be (Anna: 1, Ben: 2).
- Comparing this to Staying Out (Ben gets 0), Ben's best move is to Enter.
The Subgame Perfect Nash Equilibrium (SPNE) is (Enter, Accommodate). Anna's threat fails because, when it comes time to execute it, it's not in her self-interest.
The Power of Tying Your Own Hands
How can Anna make her threat credible? She needs to change the game so that Fighting becomes her only rational choice, or even her only possible choice. She needs a commitment device.
This is the brilliant, counter-intuitive insight from game theory: you can gain power by limiting your own options. By making a decision irreversible, you remove your ability to back down, which forces the other player to take your commitment as a given. The classic illustration is Hernán Cortés ordering his men to burn their ships upon arriving in Mexico. By removing their only means of retreat, he committed them to a fight-to-the-death strategy, which in turn changed the Aztecs' calculations.
The following video provides an excellent walkthrough of this "burning bridges" or "tying hands" concept.
Game Theory 101: Tying Hands/Burning Bridges
This video by William Spaniel uses a simple game tree to demonstrate how removing an option (the ability to retreat) can lead to a better outcome for the player who limits their own choices.
Watch the entire video. Pay close attention to how the analysis changes in the two scenarios: When Country 1 does not burn the bridge, it cannot credibly threaten to fight, because retreating is a better option if attacked. See this analysis from this point. When Country 1 does burn the bridge, the threat to fight becomes credible because it's the only option left. This forces Country 2 to concede. Follow this logic from this segment.
As the video demonstrates, by burning the bridge, Player 1 makes their threat to fight credible. Player 2, recognizing this, finds it in their best interest to concede. By giving up an option, Player 1 engineers a better outcome.
A Taxonomy of Commitment Devices in Relationships
To make a threat or promise credible, a player must employ a commitment device—a strategic action that makes backing out of the stated intention prohibitively costly or impossible. Drawing from the work of Dixit, Nalebuff, and Schelling, we can categorize these devices. The slides below provide an excellent overview.
4.2 — Credible Commitments - Game Theory
These lecture slides from Ryan Safner's game theory course offer a concise summary of commitment problems and the tools used to solve them.
First, review the slides covering the general concept of commitment, the time-inconsistency problem, and the list of eight methods to make strategies credible.
Let's explore these methods with scenarios relevant to your interests.
1. Establish and Stake Your Reputation
A reputation for being trustworthy, for keeping one's word, or even for being stubbornly immovable on certain issues, is a valuable asset. The cost of breaking a commitment is the damage to this future asset.
- Scenario: A well-respected bull in the lifestyle has a reputation for strictly adhering to the couple's rules. If he promises a cuckold, "I will not perform act X with your wife," that promise is credible because the cost of breaking it (losing his reputation and future opportunities) is higher than the short-term pleasure of the act. In his lecture, Thomas Schelling discusses this from a negative perspective: the social cost of being known as a "snitch" acts as a powerful commitment device against confessing.
Game theory of conflict by Thomas C Schelling
In this segment of his lecture, Nobel laureate Thomas Schelling explains how social context and reputation—the fear of being known as a "snitch"—can prevent a person from choosing the most materially profitable option in the Prisoner's Dilemma.
Please watch the section from this timestamp, where Schelling discusses how living in the same neighborhood or having children in the same school makes snitching extremely costly in the long run.
2. Write Enforceable Contracts
A formal agreement introduces a third party (the contract itself, and the social pressure it represents) that imposes penalties for non-compliance.
- Scenario: Ben and Anna, from our earlier example, write down a "Relationship Agreement." Anna agrees to try the new kink, but with specific limits. Ben agrees to specific aftercare protocols. While not legally enforceable, the act of writing it down makes the commitment explicit and psychologically binding. Violating the agreement now feels like a more significant transgression.
3. Burn Bridges Behind You
This involves taking an action that makes it physically impossible to reverse your course.
- Scenario (Making a Threat Credible): Let's revisit Anna, who wants to deter Ben from pursuing a new partner, Chloe. Anna's threat, "If you see her, we're through," is not credible. But what if Anna "burns a bridge"? She could tell her entire family and close friends, "Ben and I have agreed to be exclusive. If that changes, our relationship is over, and I'll be counting on your support." Now, if Ben sees Chloe and Anna backs down, she faces immense social cost and embarrassment. She has made it too costly for herself to retreat, making her threat credible.
4. Leave the Outcome Beyond Your Control (Brinkmanship)
This is a more subtle tactic where you deliberately create a situation with a shared risk that you don't fully control. The goal is to make the situation so fraught with danger that the other player backs down.
- Scenario: A cuckold is anxious about the intensity of his wife's upcoming date. He tells her, "Look, you know that when you stay out past 2 a.m. on a date, I get severe anxiety and can't sleep for days. I can't help it; it just happens. I'm not telling you what to do, but that's the risk." He isn't making a direct threat. Instead, he's "leaving it to chance"—the 'chance' being his own uncontrollable emotional reaction. He creates a shared risk of a miserable few days that his wife may choose to avoid by coming home earlier. This is the essence of Schelling's brinkmanship.
This comic illustrates a different kind of commitment problem—a mismatch in the fundamental structure of commitment itself.

Making Promises Credible
The same logic applies to making promises. A promise is only credible if the other player believes you will have an incentive to keep it when the time comes.
Consider the Agency/Trust Game:
- Principal (Ben): Decides whether to
Invest(trust Anna with more freedom) orDon't Invest. - Agent (Anna): If Ben invests, the "returns" are high (a great experience for Anna, potential for compersion for Ben). Anna can then
Sharethe returns (honor the trust, engage in aftercare) orKeepthem (get swept up, neglect Ben's feelings).
Anna's promise, "Trust me, I'll Share," is not credible if Ben believes that in the heat of the moment, her incentives will change and she'll choose to Keep. To make her promise credible, Anna needs a commitment device.
4.2 — Credible Commitments - Game Theory
Let's return to the lecture slides to see how commitment devices can be used for promises.
Please read the section titled "Promises and Applications", which introduces the trust game. Then, focus on the mechanisms for making promises credible, such as reputation and collateral (or "hostages"), and the role of contract law.
- Using Collateral ("Hostages"): In a relationship context, a "hostage" is something of value to the promiser that is put at risk. Anna could give Ben something she values—her journal, a favorite piece of jewelry—to hold during the date, saying, "This is to remind you that I'm coming back to you." The object itself is less important than the symbolic act of placing something she values in his care, making her promise to return emotionally more tangible and credible.
- Moving in Small Steps: Instead of a full weekend away, Anna can build trust by making a promise for a shorter, three-hour date first. By successfully keeping a small promise, she builds a reputation that makes her future, larger promises more credible.
Conclusion
Today, we've moved beyond analyzing a static game to understanding how players strategically manipulate the game itself. You've seen that rational players don't take threats and promises at face value; they look ahead to see if the incentives will hold. This leads to the central paradox of commitment: freedom of choice can be a strategic liability.
Key Takeaways:
- Commitment Problem: A threat or promise is not credible if, when the time comes to act, it is no longer in the player's best interest to follow through.
- Strategic Value of Limiting Options: By making a course of action irreversible or prohibitively costly to reverse (tying your hands), you can make your intentions credible and force other players to adjust their strategies to your benefit.
- Commitment Devices: These are the tools for making commitments credible. They include staking your reputation, creating binding contracts, burning bridges, using brinkmanship, and employing collateral.
- Universality: The logic of credible commitment applies equally to making threats and making promises. Both require demonstrating that you will have an incentive to follow through when the time comes.
Preview of the Next Lesson:
We have seen how a single player's move can alter a game. But how do partners' actions and investments influence each other in an ongoing, reciprocal way? In our next and final lesson of this module, we will distinguish between strategic substitutes and complements. This will help us model questions like: "If my partner invests more in their fitness, does that incentivize me to do the same (a complement), or does it make me feel I can slack off (a substitute)?" This will provide another crucial lens for analyzing the long-term stability and dynamics of a relationship.