logic vacuum 

When someone says something so ridiculous they suck the logic right out of you

She's such a logic vacuum she thought there were actual lions in Michigan

logic vacuum by Logicvacuum June 7, 2017

Vacuum Logic

A term for reasoning that assumes perfect isolation from context, much like physics in a vacuum ignores air resistance. Vacuum Logic works in idealized environments but fails in the messy real world. It is used pejoratively in online debates to criticize arguments that rely on oversimplified assumptions: “Sure, in vacuum logic, your model works – but reality has friction, variables, and human irrationality.” For example, a pure free-market argument that ignores externalities is vacuum logic. It’s also a self-deprecating term among logicians: “Our formal system is vacuum logic; it’s sound, but don’t expect it to handle ambiguity.” The term is not a formal logic but a critique of logical purity detached from application.

Example: “His economic model assumed perfect information and rational actors – classic vacuum logic. She said: ‘In a vacuum, it’s elegant. On Earth, with actual humans, it’s useless.’”

Vacuum Logic by Dumu The Void May 27, 2026