The Illusion of Simplicity Selection: On Redundancy Elimination in Completely Equivalent Theories (2)

Eddy Keming Chen argues in "The Simplicity of Physical Laws" (*Noûs*, 2025) that the principle of simplicity is a fundamental epistemological guide for discovering physical laws, and that regardless of one's metaphysical stance (Humeanism or non-Humeanism), one must appeal to simplicity to select among candidate theories. This paper raises a fundamental challenge to this argument: **Simplicity selection is legitimate only between completely equivalent theories, and in such cases, choosing the "simple" theory actually amounts to simultaneously selecting both equivalent theories—merely omitting the redundant statement of the complex version**. This paper argues that: (1) When two theories are completely equivalent, they are ontologically and epistemologically the same theory in different formulations; (2) Choosing the simpler formulation does not mean selecting a theory "more likely to be true," but only eliminating linguistic redundancy; (3) The principle of simplicity is therefore not a guide to discovering truth, but merely a pragmatic criterion for eliminating redundancy; (4) Using the principle of simplicity in non-completely-equivalent cases is actually cognitive bias, not epistemological rationality. This argument reveals that the preference for simplicity in scientific practice may not be because the universe is truly "simple," but only because we are cognitively unable to handle redundant formulations. Simplicity does not point to truth, only to operability.