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.

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6 comments, sorted by Click to highlight new comments since: Today at 5:59 PM

I wrote some more potentially-disagreeable statements for the DC meetup today. Here are the ones that were actually controversial:

  • If I had the option to have my brain uploaded with perfect accuracy into a simulated life better than my current life, but only if it destroyed my physical brain and body in the process, I would take it.
  • Having more children today improves the world overall.

A good way to find good statements for this is asking random attendees: "What view do you have that you think lots of people here might disagree with?"

Couple more examples that came up from that:

  • Believing in the supernatural gives you benefits that you can't achieve without such beliefs.
  • If I had the option to use a Star Trek teleporter (which breaks down your body atom-by-atom and reassembles it somewhere else), I would/would not.
  • Morality exists independent of people in the world.

Your suggestions have been added to the list, thank you!

Thanks for writing this up! We tried this out in our group today and it went pretty well :-)

Detailed feedback:

Because our venue didn't have internet I ended up designing and printing out question sheets for us to use (google docs link). Being able to compare so many responses easily, we were able to partner up first and find disagreements second, which I think was overall a better experience for complete beginners. The takes that you were most polarized on with any random person weren't actually that likely to be the ones that you feel the most strongly about, and there were generally a few options to choose from. So we got a lot of practice in with cruxing without getting particularly heated. I'd like to find a way to add that spice back for a level 2 double crux workshop, though!

We repurposed using the showing fingers for agreement/disagreement for coming up with custom questions; we had quite a few suggestions but only wrote down the ones that got a decent spread in opinion. This took a while to do, but was worth it, because I was actually really bad at choosing takes that would be controversial in the group, and people were like "wtf Jenn how can we practice cruxing if we all agree that everything here is a bunch of 3s." (slightly exaggerated for effect)

I didn't realize this until I was running the event, but this write-up was really vague on what was supposed to happen after step 3! I ended up referencing this section of the double crux post a lot, and we ended up with this structure:

  1. partner up and identify a polarized opinion from the question sheet that you and your partner are both interested in exploring.
  2. spend 5 minutes operationalizing the disagreement.
  3. spend 5 minutes doing mostly independent work coming up with cruxes.
  4. spend 15 minutes discussing with your partner and finding double cruxes. (in our experience, it was actually quite rare for the cruxes to have overlapped!) you'll very likely have to do more operationalizing/refining of the disagreement here. (I'm not sure if that's normal or if we're doing it slightly wrong.)
  5. come back together in a large group, discuss your experience trying to find a double crux and one learning from your attempt to convey to the rest of the group so everyone learns from others' experiences/mistakes. I did this in lieu of the checking in, because the discussions all seemed pretty tame.
  6. repeat from step 1, with a different partner and different opinion.

We did two rounds in total. People unfortunately did not report that the second round was generally easier than the first, but seemed to overall find the workshop a valuable experience! One person commented that it led to much more interesting conversation than most readings-based meetups, and I'm inclined to agree.

Thanks for the feedback!

I've added a link to your google doc in Variations! We've got a bunch of different ways to pair people now, that's cool :) I think I'm going to try your handout next time I run this, I'll let you know how it goes!

I also added a bit more to step three, with a little more detail on what the pairs are doing. I'll probably come back and try to break it down a bit more later; I'd sort of given the steps after "So how do we actually do this?" but this does have less detail than I'd like and doesn't stand alone as well as it could as an explanation.

Feedback and comments are valued on this one even more than usual. This is the least boxed of the meetup writeups I've done so far, and the one where I feel I've added the least.

I rewrote the pair sorting code to pull from the output of a Google form, so you can just copy-paste and click a button to get the output. Should be easier to use than the Jupyter notebook version, and maybe easier/more robust than doing it finger-wise.