Having read Julia Galef's Scout Mindset, you probably want to hold your beliefs lightly and update them frequently. A shortcut to this can be finding people you disagree with (but still share a lot of common ground), and getting with them into fruitful discussions. By that, you capitalize from someone else's research and reasoning and can faster update compared to doing the work alone.

This of course works only as long as you both share enough premises and you can trust the other's abilities and good intentions in research and reasoning. So you want a method that both quickly exposes mismatches here and also gets to the core of your disagreement.

A good format for such fruitful discussions might be the Yes/No debate. I created it a few years ago and already ran offline & online workshops, volunteer-based online debates and created a subreddit where everybody can start their debate. The format can help to find Double cruxes and Decision boundaries, if not resolve a disagreement between two people.

Having run and seen many debates with interested "laypeople" (who picked a topic mainly for testing the format), I'm now curious to see how well it may work with well-informed people that are deeper involved in the topic they discuss. This is why I'm writing this post.

What is a "Yes/No debate"?

A "Yes/No debate" is a discussion between two people based on yes/no questions. Basically, one person always asks a Yes/No question and the other responds to it with 5 possible answers:

• Yes
• No
• Depends
• False premise
• I don't know.

An optional reasoning may be added, Depends and False premise require an elaboration.

Given the answer, either the same person may ask again or the roles switch. We switch roles to make sure both participants stay aligned (more on this below).

What are the benefits?

The main benefit of the method is that no argument or question gets ignored: Your counterpart has to answer you, and they have to do it in a clear and decisive way (one of the 5 responses).

But also you are challenged: you have to remember what your partner answered in order to ask a suitable follow-up question. Even more, you need to know clearly for yourself why you believe something.

Compared to other formats, both of you are constantly aligned: You only get to speak as long as the other can follow you. There is no wasting time by 'splaining points the other one already agrees to or that are irrelevant to them.

From the tests we ran, we know that with this method, 50% of the participants could better understand their counterpart's position, compared to other debates they had.

One participant particularly enjoyed this:

It was surprisingly good to have a focal point to respond to. Even if they posted a wall of text explaining their position, the question was the only thing I felt required to address, so it took less mental energy to debate than it would have taken in a different format.

What questions to ask?

New Yes/No debaters often find it difficult to phrase Yes/No questions. In fact, even trained debaters find answering much easier than asking.

But if you know why you believe what you believe, it should not be that hard. Consider this (very simplified) argument tree on why someone took the Covid vaccine:

           I should take the Covid vaccine. 
          ↗                                ↖
    Covid is dangerous.             The vaccine is safe.
          ↑                                 ↑ 
Many people die from Covid.     Few people die from the vaccine.

The argument tree contains claims (nodes) and conclusions (edges). If you met someone who disagrees with the root claim ("I should take the Covid vaccine."), they must disagree with at least one of the sub-claims or conclusions.

So to find that mismatch, you may traverse the argument tree by asking:

• Do you agree that many people die from Covid?
• Does this mean that Covid is dangerous?
• Do you agree that few people die from the vaccine?
• Does this mean that the vaccine is safe?
• Does from both follow that you should take the vaccine?

Again, if they disagree with the core claim, at least one of the answers must be a No. Finding that spot in the tree helps you a lot: You then have a new disagreement but a more specific one (on which you can apply the Yes/No format again, like a recursion).

This may remind you of the Double crux method, which can be summarized as: Find relevant pillars of your and your partner’s beliefs and dig deeper until you find claims that can be easier fact-checked.

And it may also remind you of Aumann's agreement theorem, which I like to summarize as:

If you know what I know (nodes / claims / information) & we're both rational (edges / conclusions / reasoning), we must agree.

or even shorter:

Reversedly: if we don't come up with the same conclusion, we do not share the same information and/or do not apply the same reasoning.^[1]

Where to debate?

There is already a subreddit r/YesNoDebate where everyone can start a new debate or join an existing one. As there are already 100+ members, your stick will likely be picked up.

If you already know someone you share a lot of common ground with but still disagree with on some final conclusion, I might also facilitate a debate between you two. We can then use any suitable channel, be it Twitter or even a private one.

Interested?

As written at the beginning, after having run trails with volunteers and in workshops with random topics, I'd now love to see how well this format works when people use it with topics they are better informed and care about – which probably many readers here do!

So if you want to update your beliefs on e.g. longtermism, priority of AI risk, veganism, wild animal welfare or any other idea, then you may:

• start a new or join an existing debate in r/YesNoDebate
• comment or message me if you want me to guide a debate with someone you already know, or if you know a group interested in me giving an (online) workshop (like this one).
• fill out this form with a list of controversial ideas within EA, to be matched for a debate with someone disagreeing with you.

P.S.: I will also be present at EAGxRotterdam and happy to meet up.

1. ^{^}

   At this point, people often object: But what about different values? Can't they be a source of a disagreement? My answer to this: (Different) values are also results of information and reasoning. E.g. if you value human life differently than animal life then this is eventually based on the information you have about human and animal life.