"Entities should not be multiplied beyond necessity." William of Ockham wrote this in the 14th century. We now call it Occam's Razor — the principle that, among competing explanations, the one with the fewest assumptions is usually correct.
The Mechanics
Occam's Razor is a heuristic — a cognitive shortcut, not a law. It says that simpler explanations are more likely to be true because they require fewer things to go right.
Every additional assumption in an explanation is a point of failure. A theory that requires five things to be true is five times more likely to be wrong than a theory requiring one. Simplicity is a proxy for robustness.
The Modern Applications
Medicine (Diagnostic Shortcut): "When you hear hoofbeats, think horses, not zebras." Doctors are taught Occam's Razor explicitly — common presentations most likely have common causes.
Conspiracy Detection: Conspiracy theories almost always violate Occam's Razor massively. They require dozens of people to behave in coordinated, secretive, irrational ways with no leaks over long periods. The simpler explanation (incompetence, independent bad decisions) almost always fits the evidence better.
Debugging Code: Before assuming a complex, multi-system failure, check whether the simple things (wrong variable, typo, off-by-one error) explain the bug first.
The Limits
Occam's Razor is not "the simplest explanation is always true." Reality is sometimes genuinely complex. The principle is a *starting point* — begin with the simplest explanation and add complexity only when the evidence demands it.
Einstein's version: "Everything should be made as simple as possible, but no simpler."
Takeaway
Resist the urge to construct elaborate models when simple ones fit. Complexity often signals motivated reasoning, not accuracy. Sharpen your thinking with more mental models in the free CogniScroll Feed.