Commitment Contracts

Hernan Cortes would’ve made a good behavioral economist if he hadn’t decided to be a conquistador.

Cortes is famous for conquering the Aztec empire and beginning the European conquest of the American mainland.

It’s impressive that Cortes and a mere 600 Spaniards were able to take over an empire of hundreds of thousands of Aztecs.

Cortes’ men were understandably not eager to take on an entire empire. Cortes weighed their arguments, and then scuttled his ships to show what he thought of them. (No, he didn’t burn them. Though that’s a better story.)

This was a clever move for 2 reasons.

  1. It established that there was no turning back. The Aztecs were hardly likely to let the Spaniards rebuild their ships on the beach, so the only way they were leaving was if they fought and won.

  2. Mutiny was now rather pointless, because killing Cortes wouldn’t rebuild their sunken ships. They may as well let him keep leading the expedition, since now every man was valuable. If Cortes hadn’t let them leave and didn’t destroy all their ships, his men could have just killed him and sailed back to Spain, claiming that Cortes died of illness or some other likely cause.

The Aztec capital Tenochtitlan sat in the middle of a lake. It was larger than London. At the center, there was a great pyramid that stood 100 meters tall. The Spanish built a cathedral over its rubble. Mexico City stands on the ruins of the once-great city.

What Cortes did would now be called an example of a commitment contract.


Something you do that increases your commitment to doing/not doing something.

There’s a few ways of doing this. Here’s 2.

  1. Prune your set of options to make remaining ones more attractive
  2. Increase the cost of failing

A good example of the “pruning” school of thought is Odysseus. He had his men tie him to the mast in advance because he knew the call of the Sirens would be too attractive otherwise.

Since you’re not Odysseus, replace “Siren” with something more mundane like “work”.

An example of the latter is telling everyone you’re going to go skydiving on some fixed date. You better believe people will ask how it was the next day. And humans are exactly the type of creature to prefer abject terror to looking stupid.

It’s basically a carrot or a stick, even though carrots and sticks both suck.

This concept is best illustrated with a bunch of examples.


  • You commit to lose weight, so every day that you eat more than your calorie goal, you give a friend $100. Is cake worth that much to you? I bet you’d think twice about it.

  • You want to keep in touch with your friends because you don’t want to be one of those people who complain about not being in touch with them when you’re 30, so you pay them if you fail to call/meet them at least every 2 weeks.

  • You want to quit smoking. Rather than giving up money, you tell all your loved ones that you’re quitting. The shame of having to tell them you failed will help keep you on track.

Rationale, A.K.A. “Why should I give up money?”

You claim you care about a goal. This forces you to be consistent with what you told yourself by making it harder to quit that goal. It raises the cost of failure (or increases the reward of success, but it’s easier to raise the cost of failing).

By exploiting your natural loss aversion, you can do the things you know you should do, but don’t do.


I’m a sucker for tools. Call it part of my legacy as a human. And there’s a great one for commitment contracts: Beeminder

It basically specializes creating contracts for measurable goals. But with a bit of creativity, pretty much everything can be made measurable.

(Yes, you’ll have to give them your credit card to do much. Suck it up. Are you going to seriously tell me that you wouldn’t pay $100 to gain the habit of keeping a juornal or accomplishing any moderately useful goal? If you’re that hard-up for cash, I have an opening for a personal assistant.)

Some Personal Examples

I’ve used Beeminder for pretty much all these goals, since I’ve found it effective.

  • Keeping a journal every day for the last 3 years. It’s now almost 1000 pages of my life.

  • Learning Chinese by tracking time on Skype with a tutor and time spent on Skritter

  • Writing this blog. Most of my friends don’t blog consistently. I’d like to think my writing has gotten better since I started blogging, but you tell me

  • Learning how to touch type. I used to type at about 20 words per minute with 2 fingers. No wonder coding terrified me, since I took a whole minute to type a single line.


Make it Trackable

If you can’t measure or precisely track your progress, then it’s rather difficult to tell if you’re succeeding, or if you deserve a reward or punishment at that point.

Make the Tracking Automatic

This is so you can’t forget to record progress or cheat. After all, you don’t want to lose, especially as you just raised the cost of losing.

You can get pretty creative here. I’m the only person under the age of 30 that I (personally) know who’s actually completed a Coursera course. I used RescueTime and its Beeminder integration to ensure I spent at least an hour a day on the course.

Make it hard to quit

This one sounds obvious, but remember that you can bind yourself to a goal in multiple ways. Tell all your friends, pledge a lot of money, do everything to make quitting/failing more painful.

I read that Oliver Sacks vowed to kill himself if he didn’t finish writing a book in a month or so. That’s taking it to a bit of an extreme.

But hey, if your goal is important enough…

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