Occam's Razor
Prefer the explanation with the fewest assumptions, all else equal.
William of Ockham, 14th century philosopher. The principle: don't multiply entities beyond necessity. When two explanations fit the data equally well, the simpler one is usually closer to right. The complex one requires more hidden assumptions, each of which could be wrong.
The razor isn't proof; it's a prior. Simpler explanations are statistically more likely because the universe of possible complex explanations is larger than the universe of simple ones. Most complex explanations are wrong.
For operators, Occam matters in diagnosis. Most performance problems have simple explanations (incentives, capability, communication). Most strategic failures have simple causes (we did the wrong thing). The instinct to construct elaborate explanations is usually narrative-fallacy.
Examples in the wild
Most internal mysteries (declining sales, rising churn, missed targets) have simple explanations. The elaborate theories produced in internal post-mortems often miss the simple cause.
When a stock is doing something unexpected, the simple explanation (more sellers than buyers, profits disappointing) usually beats the elaborate one (sophisticated technical patterns).
When a relationship gets weird, the simple explanation (someone's tired, stressed, or upset) usually beats the elaborate ones.
Occam's Razor is one of the mental models we apply through real cases inside the Pareto MBA — a part-time program for professionals who want to think clearly about business.