Named after the 14th-century friar and logician William of Ockham, the "razor" is a metaphor for "shaving away" unnecessary assumptions to reach the most likely truth.
The Latin Maxim: Pluralitas non est ponenda sine necessitate (Plurality should not be posited without necessity).
The Modern Translation: "Other things being equal, the simplest explanation is usually the best."
The Scientific Application: It serves as a heuristic (a mental shortcut), not an absolute law of nature. It guides scientists to build models that are "lean"—meaning they explain the data without adding "ghost" variables or complex mechanisms that haven't been proven.
Classic Example: The Hoofbeats
If you are in central London and hear hoofbeats behind you, you could hypothesize:
It is a horse. (Requires 1 assumption: a horse is nearby).
It is a zebra that escaped from the zoo, found its way to your street, and is wearing silenced shoes. (Requires many unlikely assumptions).
Occam’s Razor (or the Law of Parsimony) is a problem-solving principle that suggests that when you are faced with two competing hypotheses that make the same predictions, you should choose the simplest one.
Researcher Note:
The most common mistake people make is thinking the Razor means
The most common mistake people make is thinking the Razor means