Double Crux In A Box

Summary: Teaching a particular way of debating, where you work together to find out what about the world you actually disagree on. It involves practicing by working through existing disagreement.

Tags: Small, Repeatable, Investment

Purpose: Double Cruxing is more productive method of investigating why two people disagree. This is a method that is worth practicing for disagreements elsewhere, and this is also a chance to have productive disagreement with other people.

Materials: You need a list of statements people might disagree about. A suggested list is provided here.

Announcement Text: Arguing about important things doesn’t usually lead to people changing their mind. Double Crux is a technique for making discussions more productive and understanding the actual reasoning of those who disagree with us. Sometimes it even helps to better understand the foundations of your own beliefs.

We’re going to meet up, learn about the Double Crux, and then break into pairs with someone we disagree with to practice finding out why our views are different and what might change our minds.


1. Explain how a double crux works. A suggested explanation is below, but if you feel comfortable with the technique you should feel comfortable elaborating or adjusting this.

What’s the point: “Double crux is a way of disagreeing more productively. Normally, when we disagree we get into so-called soldier mindset where it’s a competition and you need to beat the other persons argument. This is deliberately different, and if you notice you’re trying to beat them then you should pause, take a step back, and try and collaborate.”

What’s a crux: “A crux is a fact about the world that, if it were false, would cause you to be less sure of your conclusion. You can have more than one crux, and it’s quite possible that you won’t be able to explain all of your cruxes, but ideally you would be able to list all of them and if all of them were false then you would change your mind. One example might be, if you think it’s immoral to eat meat, a crux is that you think the animals we eat suffer, and if it turned out they didn’t then you’d be alright eating meat. Another example might be, if you think parks are great places to hold meetups, a crux is that you think the weather is generally comfortable outside, and if it turned out that most people found the weather really uncomfortable then you’d think parks were bad places to to hold meetups.”

What’s a double crux: “A double crux is something that’s a crux for both you and the person you’re talking to. To use the example above, if I think the weather is comfortable and you think it’s uncomfortable, and we’d change our minds if we were wrong about that, then we’ve found a double crux. We disagree about the facts in the world, and we do agree that fact matters. Again, it’s okay to have multiple cruxes and it’s fine to not be able to articulate your cruxes, but if you find that you always have more cruxes and you can’t say for sure that there aren’t others you aren’t thinking of, this technique isn’t going to be very helpful for you in disagreements.”

Acknowledge this is hard: “Saying your cruxes out loud is hard! Finding them involves some introspection, and laying them out in front of another person where you might be proved wrong is a brave act. We hope in the process of finding where you actually disagree with your partner, you’ll find you have more in common with them and your disagreements are less all-encompassing than you might have thought before. Thank you for being willing to create a space where it’s safe to explore nuance, and to allow that you might turn out to be wrong.

This technique will only work if you start from the assumption that you might be wrong. I’m not saying that you are. I’m only saying that both people have to go into it understanding that it’s possible. Otherwise, how can you ask the other person to be willing to change their mind when you aren’t willing to change yours?

Actual steps: ”So how do we actually do this? First, you’re going to think about your cruxes on the issue and make a list while your partner does likewise. A piece of paper and a pen might help. Then, you’re going to go over your lists together and see if there are any that pair up into a double crux. Last, you’re going to look together at how you might find out what the actual fact in the world looks like, what kind of test would indicate the answer was one way or the other. If you still have disagreement, sit with it for a moment and repeat those steps.”

2. Say “To practice disagreement, first we need to figure out what we disagree on. I’m going to read out some statements. Raise your hand after each one with fingers showing how strongly you agree or disagree. Five fingers outstretched if you strongly agree, three fingers raised if you’re in the middle, one finger raised if you strongly disagree. If you’re uncomfortable discussing the statement, then I want you to hold up three fingers or to not hold your hand up at all, your choice. Any questions?” Answer questions as people ask them. “Okay then. As you’re holding up your hand, look around for people who disagree with you. 1s, look for 4s and 5s. 5s, look for 1s and 2s. Once you find a partner, pair off and feel free to move a little bit away from the group to start finding your cruxes.”

There’s several different ways to sort people. I like the finger method because it requires the least preparation, but the other methods can sort for more disagreement, be faster, or have other benefits. See the Variations section below.

3. Start reading the statements. Be sure to wait a minute or so after reading each one out, repeating the statement at least once. Again, a suggested list is here but you should feel free to come up with your own. People should be pairing off as you do.

3b. Each member of a pair should generate their own cruxes. Remember, a crux is a fact about the world that causes you to hold your position, such that if that fact was different for each crux you’d change your mind. If you think a bridge will collapse because the last three bridges built like that collapsed then that’s a crux, and if it turns out the last three bridges built like that didn’t collapse you’d be less sure this one will collapse.

3c. Compare your cruxes to your partner’s cruxes. If there’s anything on both lists where you think the fact about the world is different, that’s a double crux. Go check with the world. (Wikipedia is your friend.)

3d. If there’s nothing on both lists even if you rephrase something a little, that’s fine. It means you care about different facts in the world when reaching your conclusion, and possibly have different values. It’s not a failure not to happen to have double cruxes. Where you discuss the topic from here, keep in mind what would actually change each other’s minds.

4. Go around and check in with the pairs. Answer questions about the technique, help moderate if things are getting heated, and always ask if they feel this is helping.

Variations: If you’re comfortable with Jupyter Notebook and your audience has internet capable devices, Sam created this code to do a more exacting job of matching people with partners. To use it, swap out step 2 with directions to your online survey.

Another matching variation is Maia’s Double Crux Helper. If you make a Google form or other survey tool and convert that to a CSV, the Double Crux Helper will give you pairs. You can potentially even do this before arriving at the meetup by asking people to fill out the form before coming, though I’d recommend being ready to rerun the helper at the meetup since I predict some people will show up without having filled out the form.

Jenn made this Double Crux Coordination sheet to match people, which you can print a bunch of copies of and have people fill out at the meetup. This means you need to prepare the sheets, but also means you don’t need internet at the meetup itself. People can either visually compare them, or if they filled out the answers in dark enough ink they can overlap the sheets and hold them up to the light.

You can, of course, create variations by changing the questions. The suggested list makes an attempt to avoid obvious political hot button issues, not create too much anger and heat, be something most people have an opinion on, while still being things people disagree about. You can of course toss out the first two goals or even reverse them. Pick whatever politics or deeply felt identity issues you think will make people stand up and take notice. I don’t recommend this personally (politics is the mindkiller!) but I don’t deny that people flock to where they can discuss politics and some find it fun.

You can also curate your list to your specific group. That seems more promising to me, albeit not something I can provide for you. Toss out the goal of most people being able to have an opinion on it and make your list entirely about Land Value Tax, or AI Policy, or the proper way to celebrate Petrov Day including whether or not to have a button that shuts down LessWrong.

Notes: Step four involves some moderation skills. You are deliberately creating conflict and asking people to work through it.

However you sort people into pairs, I feel the bit about allowing people to opt out of discussing a statement is important. The things we feel really heated about are the things that double crux can be most useful in, but they aren’t always the best places to learn the technique and some of your attendees might be newcomers or strangers to the others.

I think it’s helpful to do multiple cycles of Double Crux during a meetup. Pair up, look for double cruxes, discuss, then come back together as a big group before pairing up with someone else on a different topic. Two short cycles is better practice for the technique than one long cycle.

Credits: This was adapted from an activity run by Sam Brown, which was in turn adapted from CFAR’s development of the technique. Be aware this description gives you fourth-hand knowledge, and transcription errors may have crept in.