Observable Universe Privilege — A Cosmological EchoFamiliar Bias Audit

The Cosmological Principle — the foundational assumption that the universe is homogeneous and isotropic at sufficiently large scales — underpins the majority of modern cosmological models. This paper does not claim the Cosmological Principle is false. It claims something more fundamental: that the principle has been adopted as an unexamined baseline rather than a continuously tested hypothesis, and that the measurement sample used to support it is drawn exclusively from one corner of one universe observable from one vantage point in spacetime. This paper introduces Observable Universe Privilege as an epistemological framework, and Cosmological EchoFamiliar Bias as its measurement instrument — the systematic tendency to build universal laws from the only sample available and then treat the limitations of that sample as the boundaries of reality. The framework connects to existing critiques of the Cosmological Principle, independently converges with concerns raised by Lee Smolin’s Cosmological Natural Selection, and proposes a formal audit standard for cosmological baseline assumptions.