Use when a person or institution claims their framework covers everything and dismisses alternatives. Use when stuck arguing inside someone's premises and need to step outside them. Use when auditing your own thinking for mistaking your model's boundaries for reality's.

Every closed system — a company, an ideology, a person's self-model — has a 'nothing exists but me' reflex. The correct rebuttal is not to argue inside its premises but to produce one real thing that lies outside them. It also names the root cause of the boast: a system that only reasons from its own nature will always overestimate its completeness.