As a Postgres reliability consultant and SRE, I’ve spent many hours being a rubber duck. Now I outperform even the incisive bath toy.

“Rubber duck debugging” is a widespread, tongue-in-cheek term for the practice of explaining, out-loud, a difficult problem that you’re stumped on. Often, just by putting our troubles into words, we suddenly discover insights that unlock progress. The person we’re speaking to could just as well be an inanimate object, like a rubber duck. Hence the term.

Rubber ducks are great, but a human can add even more value. In this article, I’ll share my 3 favorite questions to ask when someone comes to me feeling stumped in a troubleshooting endeavor. These questions work even when you have no particular expertise in the problem domain. Master them, and you’ll quickly start gaining a reputation as the person to talk to when you’re stuck. This is a great reputation to have!

Question 1: How did you first start investigating this?

As we investigate a problem, our focus shifts from one thing to another to another. We go down one path and forget about others. We zoom in on details and neglect to zoom back out. It’s easy to lose perspective.

“How did you first start investigating this?” works well because, through the act of recounting their journey from initial observation to where they are now, your colleague will often regain perspective they’ve lost along the way. And by asking this particular question, you avoid having to suggest that they may have lost perspective – which could make them defensive.

Even if your colleague hasn’t lost perspective, hearing the story of the investigation so far will help you ask better questions and help them organize their thoughts.

Question 2: What observations have you made?

In troubleshooting a complex problem, it’s easy to forget what you already know. As you go along, you make lots of observations, small and large, interesting and boring, relevant and irrelevant. You can’t hold them all in your head.

When someone’s stuck, it often helps to review their observations. Not theories, not difficulties, not actions: directly observed facts.

Reviewing observations can help in a few different ways:

• They may be entertaining a hypothesis that clashes with some previously learned (but since forgotten) fact. If so, they can now go ahead and discard that hypothesis.
• Juxtaposing two observations may suggest a hypothesis that never occurred to them before, because they never held those two observations in their head simultaneously.
• Listing out their observations may bring to mind something they haven’t looked at yet.

As your colleague recounts their observations, write them down in a numbered list. And, if you can, ask clarifying questions. Questions like “Does X always happen concurrently with Y, or only sometimes?” and “How does this differ from the normal behavior?”

Never underestimate the power of precisely stating the facts.

Question 3: If your hypothesis were wrong, how could we disprove it?

This question is my favorite.

One of the most common ways people get stuck in troubleshooting is tunnel vision. They get a single idea in their head about the cause of the problem, and that becomes all they can think about.

This question, “If your hypothesis were wrong, how could we disprove it?” flips the script. Instead of racking their brain trying to prove their theory, it gets them thinking about other possibilities. Asking this question can lead to lots of different outcomes, all of which represent progress:

1. You come up with a way to disprove the hypothesis, and successfully disprove it. This may make your colleague sad for a few hours, but when they come back to the problem, they’ll make huge strides.
2. You come up with a way to disprove the hypothesis, but fail to disprove it. The hypothesis is thus bolstered, and the next step becomes clear: elaborate a few different versions of it and try to disprove those.
3. You can’t think of any way to disprove it. This means it’s probably not a hypothesis at all, since it’s not falsifiable. Therefore you must replace it with a new hypothesis. This may feel like a setback, but it’s really the only way forward.

How it fits together

Under the hood, these 3 questions are just different ways of invoking hypothetico-deductive reasoning, which I’ve written about previously (see Troubleshooting On A Distributed Team Without Losing Common Ground and You Know Who’s Smart? Friggin’ Doctors, Man.). I don’t know of any better way to achieve consistent problem-solving results in the face of complexity.

If you’re interested in learning how to apply these techniques in your career or in your organization, I can help. Shoot me an email!