Occam’s Razor

Occam’s Razor is one of the general-thinking models in The Great Mental Models Volume 1 — General Thinking Concepts, summarized there as: “Simpler explanations are more likely to be true than complicated ones.” Rather than waste time disproving complex scenarios, you “make decisions more confidently by basing them on the explanation that has the fewest moving parts.” The book traces it to William of Ockham’s formulation that “a plurality is not to be posited without necessity,” and gives it the memorable clinical heuristic: “When you hear hoofbeats, think horses, not zebras.” Kyle’s notes pair it with Louis Gerstner’s turnaround of IBM as a real-world case — Gerstner’s famous “the last thing IBM needs right now is a vision,” choosing simple, tough-minded execution over a grand rabbit-out-of-the-hat strategy.

The book is careful to flag the model’s limit, which the wiki preserves: “some things are simply not that simple.” Pyramid schemes and Ponzi schemes recur not by miracle but as “a result of a complex set of behaviors” — so the simplest explanation isn’t always the right one, and parsimony is a default to be overridden when the evidence demands it.

Context: Occam’s Razor (the “law of parsimony”) is a principle attributed to the medieval logician William of Ockham, holding that among competing hypotheses, the one with the fewest assumptions should be preferred — widely used as a tie-breaking heuristic in science and problem-solving.

Where this appears

• The Great Mental Models Volume 1 — General Thinking Concepts — dedicated treatment (“horses not zebras,” Ockham’s formulation, the IBM/Gerstner case) plus the counter-caution that some things genuinely aren’t simple.