"Miller's Law" is Ambiguous and Often Misused

WHY IT EXISTS: The term "Miller's Law" became popular, but it was independently applied to the work of different people named Miller, or to different concepts from the same person. This historical coincidence created a term with multiple, unrelated meanings, causing persistent confusion in technical and design discussions.

THE MENTAL MODEL: Think of "Miller's Law" not as a specific rule, but as a homonym in technical discourse. Like the word "sanction" which can mean to permit or to prohibit, "Miller's Law" requires context to be understood. The correct mental model is to immediately ask "Which one?"

HOW IT WORKS: The term works by causing miscommunication. When one person cites it, they might be referring to a principle from psychology (often misapplied), while another might think of a concept in online communication or another field. There is no single "it" for how "it" works. The only mechanism is a shared name for different ideas.

WHEN TO USE IT: Use the term "Miller's Law" with extreme caution. The only safe use is to explicitly state which principle you are referring to—for example, "George A. Miller's concept regarding short-term memory..."—or to point out the ambiguity itself as a topic of discussion.

WHEN NOT TO USE IT: Do not use the term "Miller's Law" without qualification. Dropping it into a conversation or document as if it has a single, universally understood meaning is a recipe for miscommunication. It's a classic example of "jargon-hiding," where a term sounds impressive but obscures meaning because it's imprecise.

ONE CANONICAL EXAMPLE: A UI designer mentions "Miller's Law" to justify limiting a navigation menu to 7 items, referencing George A. Miller's work on short-term memory. A community manager in the same meeting thinks of the "law" from online communities about group dynamics. Both are correct about a Miller's Law, but they are having two different conversations. This highlights the critical need for clarification.