Of the things I learn at work, the lesson that sticks with me most is: “Always be MECE.”
MECE (pronounced 'Mee-See') stands for Mutually Exclusive and Comprehensively Exhaustive. It means that every option is covered without overlap—nothing is missing, and nothing fits in two places at once. Here’s an example:
Select the answer that best describes your desire for pizza.
Yes, Pizza!
No, Pizza!
Other
Yes and No can’t exist at the same time. And it’s possible that you may be “Sure, but not right now” which would go in “Other.”
I recently got a CT Scan. At the hospital I filled out a form asking if I had allergies. The form asked me to select “Yes” or “No”. I believe that’s wrong, and it’s certainly not MECE. I don’t know if I have allergies—so how can I confidently say 'Yes' or 'No'?. I wrote in a checkbox and titled it “Unknown.”
The nurse, upon reading my form, sighed and said, “Mr. Brady, please, do you have allergies?” I responded, “I don’t know if I do. And without knowing what I might be allergic to, how could I confidently answer yes or no? And I will not claim that I have or don’t have something when I can’t support that claim with any evidence. That’s how conspiracies start.”
I’m not a difficult patient. That said, the more I learn about what knowledge is and how it’s acquired and how we use knowledge as inputs in a system, the more I want to be careful about claiming what I have or don’t have knowledge of.
We prefer certainty over ambiguity. And unchecked certainty could give rise to hubris.
What’s better: Humility > hubris.