The Rule of Three: The Principle for Error Recognition and Critical Rethinking – Dan Orr

Teaching Your Customers To Know When to Say When

Dan Orr, President, Dan Orr Consulting

IN COMPLEX SITUATIONS or in sports where the risk could potentially be significant, making mistakes is inevitable. Experienced professionals, such as diving instructors and divemasters, know that the difference between a minor misstep and a catastrophic failure often hinges on recognizing errors early and responding with deliberate caution. This is especially relevant when you consider that, as diving professionals, we have a duty of care to not only keep ourselves safe but also those in our charge. Considering all the things that are involved in preparing for a diving expedition, a dive charter or student evaluation dives, recognizing pre-dive errors or mistakes is absolutely crucial to everyone’s safety.

Mistakes or errors, even minor ones can compound increasing the likelihood of a diving accident. Therefore, an area I believe is crucial in scuba diving safety is “The Rule of Three.” It is the simple, yet significant, practice of stopping and reassessing when three mistakes are made or errors have occurred. This principle, rooted in the wisdom of experience and supported by cognitive science, serves as a vital checkpoint for both individual divers and dive teams.

The ”Rule of Three” is such an important tool in diving safety and risk management that I added it to the book that my wife, Betty and I wrote, 101 Tips for Recreational Scuba Divers as Tip #16, “Dan Orr’s Rule of Three.” At its core, the rule states that if you make three errors, or encounter what could be considered as three warning signs, you should stop, take a deep breath and rethink what you are doing before proceeding. 

Though an important precept in scuba diving safety, where the risks associated with mistakes can certainly compromise safety for you and the people you dive with, the “Rule of Three” has broad application in many parts of our lives. In essence, it is like a self-imposed circuit breaker, a moment to pause, take stock of what you are doing and how you are doing it, and deliberately consider whether it is wise to continue, possibly change tactics, or abort the activity altogether.

Mistakes rarely happen in isolation. Human error is often the result of a chain of events: small missteps compounding until a critical threshold is breached. Going beyond that critical threshold can change an enjoyable recreational scuba dive into something with a truly undesirable outcome. The “Rule of Three” acknowledges this cumulative effect. By the time three mistakes have occurred, you may be statistically more likely to make a fourth, and the risk of serious consequences increases significantly.

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Stopping after three errors interrupts this escalating chain of events. It provides time and mental space to move from an automatic, possibly panicked response (known as “task fixation”) to deliberate, reflective thinking and appropriate action. This shift is crucial: when under stress, humans tend to double down, ignore warning signs, and push forward. The “Rule of Three” is a counterbalance, encouraging us to resist the urge to “chance the consequences” and, instead, prioritize safety and sound judgment.

As a safety conscious diver, applying the “Rule of Three” involves keeping a mental tally of mistakes you make or warning signs you see in your preparation for a dive. These do not have to be huge or catastrophic mistakes. They can be as simple as a forgotten tool, misread instructions, or a nagging sense that something was missed and should have been considered. The discipline of keeping track of small slips or missteps builds awareness and prevents rationalization (“Oh, it’s just a little thing; I’ll remember next time. . .”).

After the third error, it’s wise to take a deliberate pause in what you are doing. This is not a weakness or admission of incompetence; rather, it is a mark of professionalism and true concern for your safety and the safety of others around you. The act of stopping disrupts the momentum of mistakes and reduces the chance of further errors.

During the deliberate pause, it’s now time to ask yourself:

What is causing these errors? Are conditions changing? Am I tired, distracted, or under time or peer pressure? Is there something about the dive, environment, or equipment that I am uncomfortable about and needs to be addressed? Should I continue or consider aborting the dive altogether? This reflective review may lead to simple adjustments, such as reorganizing your equipment, seeking help, or taking a break. In some cases, it may mean abandoning the dive entirely for safety’s sake.

For example, a diver preparing for a deep dive forgets to check their breathing gas supply (mistake one), has made an error in assembling their equipment (mistake two), and realizes they added the wrong amount of weight to their BCD or weight system (mistake three). According to the “Rule of Three,” now is the time to stop, and take a deep breath. Instead of pushing ahead and risking an emergency underwater, the diver should reassess, determine why the mistakes are being made, correct the mistakes, or potentially choose to postpone the dive.

Even in daily routines, pausing after a series of mishaps, such as a forgotten wallet, a missed turn, a dropped phone, can be wise. The “Rule of Three” reminds us to slow down, refocus, and avoid compounding mistakes out of frustration or haste.

Why not stop after one error, or wait for five? Three is a psychologically significant number. One mistake may be an anomaly; two can be a coincidence; three forms a pattern. At three, it becomes difficult to dismiss the situation as mere bad luck. The number three is also easy to remember, making the rule practical and effective.

Like any rule, the “Rule of Three” is not infallible. Not all errors are equal – some may demand immediate cessation regardless of count, while others may be minor. The rule depends on honest and realistic self-assessment; ignoring or rationalizing errors defeats its purpose. In dynamic environments, stopping may not always be feasible, and rigidly applying the rule without regard for context can itself become a hazard.

Nevertheless, the “Rule of Three” is a powerful tool that encourages mindfulness and caution. It is a reminder that sometimes, the best action is inaction: to pause, step back, take a deep breath and look at the bigger picture.

For dive groups, making the “Rule of Three” an explicit part of diving safety culture may improve the diving experiences. Encourage diving companions to speak up when mistakes accumulate and ensure that pauses for reassessment are supported rather than penalized or regarded as personal weakness. Use debriefings and post-dive reviews to identify error chains and reinforce the value of reflective practice.

The “Rule of Three” is more than a safety protocol; it is a philosophy of humility and mindfulness. By making errors visible, pausing deliberately, and rethinking our approach, we transform mistakes from sources of potential danger into opportunities for learning and improvement.

In scuba diving, where there are often a variety of pre-dive pressures on diving professionals and divers as well, the wisdom to stop after three errors warns us: safety and sound judgment always come first. Whether we are diving in some exotic diving destination or trying to manage the challenges of daily living, the “Rule of Three” is a simple, memorable, and potentially life-saving guide. When we make mistakes, even minor ones, stop, take a deep breath and rethink before moving forward. Those in our care, will be much safer for it.

Additional Reading: Orr, D. & Orr, B. 101 Tips for Recreational Scuba Diving. 2023. Best Publishing Company (www.bestpub.com). Orr, D. & Douglas, E. Scuba Diving Safety. 2007. Best Publishing Company (www.bestpub.com).

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