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Errors Merit Post-Mortems

After people make errors, they should do post-mortems. How did that error happen? What caused it? What thinking processes were used and how did they fail? Try to ask “Why?” several times to get to deeper issues than your initial answers.

And then, especially, what other errors would that cause also cause? This gives info about the need to make changes going forward, or not. Is it a one-time error or part of a pattern?

Effective post-mortems are something people generally don’t want to do. What causes errors? Frequently it’s irrationality, including dishonesty.

Lots of things merit post-mortems other than losing a debate. If you have an inconclusive debate, why didn’t you do better? No doubt there were errors in your communication and ideas. If you ask a question, why were you ignorant of the answer? What happened there? Maybe you made a mistake. That should be considered. After you ask a question and get an answer, you should post-mortem whether your understanding is now adequate. People usually don’t discuss thoroughly enough to effectively learn the answers to their questions.

Regarding questions: If you were ignorant of something because you hadn’t yet gotten around to learning about it, and you knew the limits of your knowledge, that can be a quick and easy post-mortem. That’s fine, but you should check if that’s what happened or it’s something else that merits more attention. Another common, quick post-mortem for a question is, “I asked because the other person was unclear, not because of my own ignorance.” But many questions relate to your own confusions and what went wrong should be post-mortemed. And if you hadn’t learned something yet, you should consider if you are organizing your learning priorities in a reasonable way. Why learn this now? Why not earlier or later? Do you have considered reasoning about that?

What if you try to post-mortem something and you don’t know what went wrong? If your post-mortem fails, that is itself something to post-mortem! Consider what you’ve done to learn how to post-mortem effectively in general. Have you studied techniques and practiced them? Did you start with easier cases and succeed many times? Do you have a history of successes and failures which you can compare this current failure to? Do you know what your success rate at post-mortems is in general, on average? And you should consider if you put enough effort into this particular post-mortem or just gave up fast.

You may wonder: We make errors all the time. Should we post-mortem all of them? That sounds like it’d take too much time and effort.

First, you can only post-mortem known errors. You have to find out something is an error. You can’t post-mortem it as an error just because people 500 years from now will know better. This limits the issues to be addressed.

Second, an irrelevant “error” is not an error. Suppose I’m moving to a new home. I’m measuring to see where things will fit. I measure my couch and the measurement is accurate to within a half inch. I measure where I want to put it and find there are 5 inches to spare (if it was really close, I’d re-measure). The fact that my measurement is an eighth of an inch off is not an error. The general principle is that errors are reasons a solution to a problem won’t work. The small measurement “error” doesn’t prevent my from succeeding at the problem I’m working on, so it’s not an error. It would be an error in a different context like doing a science experiment that relies on much more accurate measurements, but I’m not doing that.

Third, yes you should try to post-mortem all your errors that get past the previous two points. If you find this overwhelming, there are two things to do:

  1. Do easier stuff so you make fewer errors. Get your error rate under control. There’s no benefit to doing stuff that’s full of errors – it won’t work. Correctness works better both for immediate practical benefits (you get more stuff done that is actually good or effective instead of broken) and for learning better so you can do better in the future.
  2. Learn and write down recurring patterns/themes/concepts and reuse them instead of trying to work out every post-mortem from scratch. If you develop good ideas that can help with multiple post-mortems, that’ll speed it up a ton. Reusing ideas is a major part of Paths Forward and is crucial to all of life.

Elliot Temple on April 8, 2019

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